I wanted to start a thread to show my Majestic 1600 restoration. I am a little late on posting progress but I'll get you up to speed. I found the unit in an antique store and fell for it pretty hard. It had a price tag on it for $125. I worked the owner down to $75 and tax and took it home that night. I thought it would just make a nice decoration in the apartment but then something started eating away at me to find out the history of the unit. Some Google searches later I found my way to this site and made the decision that I would restore it. The first thing I did was clean the insides as much as I could. It wasn't extremely dirty but it did have a fine layer of black dirt on it. It cleaned up very nicely with some elbow grease and electronics cleaner.
http://farm6.static.flickr.com/5221/5677055397_0e166bbf45.jpg
After cleaning the interior I replaced the missing tube you can see on the right hand side. I work with some one who is a wealth of electronic parts and he gave me one for free. With all the tubes in place it was time to fire it up and see what we've got. I brought the voltage up slowly with a variac and got raster :-). Unfortunately there was no vertical deflection, just a solid horizontal white line in the middle of the screen.
My next step was to pull the chassis from the cabinet and put it on a tabletop to get ready for recapping. I got a copy of the photofact and ordered my capacitors from www.wjoe.com, 17 of the them to be exact. Today I think I'll begin the recapping process.
http://farm6.static.flickr.com/5262/5677612876_eb1a2baa26.jpg

Underestimated the difficulty of replacing capacitors. I removed the first cap and I don't know where the markings are for polarity. I've read in another post
"The symbols are little cutouts in the phenolic material right next to the terminals."
I can't seem to find any markings though.
http://farm6.static.flickr.com/5149/5677616930_9c07623694_z.jpg
http://farm6.static.flickr.com/5224/5677056463_f38de0fef7_z.jpg

that's on the bottom of electroylic multistage cans. With most new caps (except electrolytics), polarity is not an issue, like resistors. The old ones had the terminal with the outside foil on it marked, not usually the ground. Be careful though, small electrolytics will have the negative marked and that must be followed. They usually have a paper or cardboard covering and are pretty easy to read. Electroytics are usually 1-2 mfd (microfarad) or higher. You usually won't see one lower than a 10 or 8 mfd. That .1 mfd you have in your hand is not an electrolytic. Some capacitors are rated in mmfd (micro micro farad), or pf (picofarad, same thing), which is even lower. Mmfd or pf caps are usually mica or ceramic.

Is this your first attempt at electronic repair? If so, I would suggest letting the TV sit for a while and buy a cheap AA5 tube radio. This will help you to identify parts and repair something that is a lot more simple than a TV. Also if you totally screw it up, like I did the first couple of times, you haven't wrecked anything important. I hope I'm not out of line. Just a friendly suggestion.

I think I'll forge ahead and break something important the first time. You have however made my evening a lot shorter. There are very few larger mfd capacitors in the set, and they are all very easy to read polarity.
http://farm6.static.flickr.com/5307/5677366673_9961d10edc_z.jpg

What kind of capacitor did I have in my first picture?

What kind of capacitor did I have in my first picture?

Wax paper. Guaranteed to be bad. Nonpolarized. Replace with "Orange Drops" or similar mylar and foil cap. Use the same capacitance (or within 10%) and same or higher voltage rating. More at http://www.wa2ise.com/radios/repair.htm

Electroytics are usually 1-2 mfd (microfarad) or higher. You usually won't see one lower than a 10 or 8 mfd. That .1 mfd you have in your hand is not an electrolytic.


I meant to say you usually won't see one lower than a 10 or 4 mfd. :banana:

Good luck, ask for help if you need it.

Here are more articles that may be helpful. The first one covers recapping:

http://antiqueradio.org/recap.htm

http://antiqueradio.org/restoration.htm

Regards,

Phil Nelson
http://antiqueradio.org/index.html

Thanks for the articles. I read both of them before actually. I did run into one more thing. I actually ran into it when ordered my caps. There is one cap that on the photofact says 600v but the one that is installed is 800v. I ordered a 630v trusting that the photofact is correct but now I'm second guessing myself into thinking I need something over 800v.

Which cap is it (Sams part number)?

Phil Nelson

I'm not sure to which part number you are referring. The parts list has an item number, which is C40. There is also replacement part numbers from-
Majestic- D03.100-12
Aerovox- P688-022
Centralab- DF-203
Cornell Dubilier- PTE6S2
Sprague- 6TM-622
The schematics state that it's used for audio coupling. Sams states .022mf capacitance and 600v voltage rating. The cap in the set is .02mf 800v.

I mean the part number given in the Sams manual (C40). 630V should be fine there.

Phil Nelson

Why do you think there is an 800v in there? Could it have been repaired in the past possibly?

Just about every old radio or TV that I've owned had at least a few repairs.

Or, perhaps the manufacturer was using up parts that they happened to have in abundance, even though the voltage rating exceeded the specified minimum. They might have gotten a great deal on a boxcar full of 800v-rated caps.

Phil Nelson

Progress!!!
Well if progress means moving backwards. I finished with the caps that I had ordered, but after spending some intimate time with the under side of the set I realized that I missed 7 electrolytics hiding under two metal cans. So they are on order and I await their arrival. I decided to fire the set up again to see what, if any, progress I have made. I fired the set up and... no raster. Moving backwards! I also thought that the flyback transformer was quieter than it was before, although that could be in my imagination. The tubes did light up pretty like a Christmas though.
http://farm6.static.flickr.com/5021/5682038562_7c41bf7832.jpg
I didn't spend much time trying to figure out where I went wrong. I figure I'll have some time in the next few days before the new caps get here.

BTW thanks so much for all of your help Phil.

Steady as she goes, Grasshopper...It ALMOST worked before, that is a VERY good sign...Somethin' THAT purty HAS to work well.

The flyback might be quieter because it's not putting out any voltage. Check your work. Believe me, I'm not doubting your ability, but I still hook up stuff wrong sometimes and I've been doing this for years. Just did it on the last one I did. Also check the tubes in the HV cage, 1B3, etc. Make sure nothing is shorting and trace the schematic on each cap you changed to make sure it went to the same spot the old one went to. Have fun, this is what it's all about.

All good things come to those who wait!!!

Spent some time looking over my work, going from solder point to solder point and making sure nothing was shorted, not soldered, etc. I also refered to my photographs to check polarity on the three electrolytics that I replaced. All of my checks turned up nothing, all looked good. What could it possibly be? I decided to give it power again and have a good look around and visibly check the tubes. I fired the set up and confirmed that all the tubes lit up. They lit up like a warm fire on a cold night. All of a sudden what do I see?

http://farm6.static.flickr.com/5182/5685353620_e3db0f9e1b.jpg

Wait for the set to warm up of course!
I forgot watching television as a child required turning the set on, going to the kitchen to get a bowl of cereal, and then returning to your Saturday morning cartoons.

Now I wait for my next batch of caps with a feeling of satisfaction that, lack of visible progress not withstanding, at least I'm not moving backwards.

A raster, yay. The bright horizontal line is the classic sign of issues in the vertical circuits. It may be cured after you finish replacing capacitors.

Don't play it long in this condition, lest it make a permanent line in the picture tube.

Phil Nelson

I set to task today and replaced the multi-stage can capacitors with new individual axial lead capacitors.

Cans I replaced.
http://farm6.static.flickr.com/5023/5701336778_3e605a3520.jpg

It was a bugger trying to find room for all of the new leads, but I got all of them in without any shorts.

After picture with the 7 new individual caps.
http://farm6.static.flickr.com/5230/5700769569_4bc06bb603.jpg

I have not yet plugged it in because I do not have a variac here at the moment. I don't know if that makes a difference now that I have replaced the capacitors but I wanted to ask all of you. Should I wait until I have a variac to fire it up, or should I fire her up all at once? I await the councils decision. :scratch2:

On a related note does any one have advice on procuring a variac? Specs, things to look for, price range, etc...?

I would use the variac. If you hit the caps with full B+, you risk damage. I had that happen once, the caps all hot really hot even though they were 'new'.

On a related note does any one have advice on procuring a variac? Specs, things to look for, price range, etc...?

They can be quite expensive depending on the amperage etc. If you anticipate doing more work on tube sets in the future, it's certainly a worthwhile investment, but for a single set, the cost:gain ratio isn't that pleasing.

You can do without one, a lot of people use what's called the "dim bulb" (no sense repeating what's in a lot of other threads/sites - a quick search will net you the details) method to protect their sets when they fire them up; it gives a nice visual indication very quickly if there is a short, and is essentially a lightbulb-based voltage divider/current limiter.

Or, you can try borrowing one... there are plenty in many university physics labs and if you're friendly with the staff they might let you borrow one for a bit. I borrowed mine when I did my Fleetwood set.

Edit: Note that I meant you can use other protections instead of a variac, not that you can just fire it up without any safety!!

"If you anticipate doing more work on tube sets in the future, it's certainly a worthwhile investment"

Hehe, I think that ship is sailed. I'm in pretty deep already. I have a set in my basement ready for round two, and I'm constantly on the lookout for rounds 3-26.

"If you anticipate doing more work on tube sets in the future, it's certainly a worthwhile investment"

Hehe, I think that ship is sailed. I'm in pretty deep already. I have a set in my basement ready for round two, and I'm constantly on the lookout for rounds 3-26.

That is pretty much a moot point indeed for anyone who has the space/skills. Once you do one, you have an itch to do more. Everyone here's been bitten, I think. :D However, I do imagine there must be people that do "Just One™" because it was their grandfathers or whatever and has particularly special value to them, but they have no interest in other sets.

(sadly, I have neither a lot of space, nor does anything overly interesting ever pop up in my area. I only got my fleetwood because the previous owners left it in the hayloft of our barn.) Sure, there's the odd AA5 that some idiot wants $200 for, but given my limited space (look at my nickname and if you need a better hint, my website, then take a guess with what it's filled...) and already having a tube radio, I _really_ want to do a tube-based TV set.

It helps avoid shorts if you place stripped off wire insulation on the bare cap leads. "Spaghetti" they call it. You can make your own from scrap wire of large enough gauge (old house wire or power cord) or even use coffee stirrers (very small straws).
http://farm6.static.flickr.com/5230/5700769569_4bc06bb603.jpg http://pw2.netcom.com/~wa2ise/radios/spplug.gif The "dim bulb"
For a quick substitute for a variac, wire up two outlets in series. One outlet plug in a lamp that has say a 100W light bulb, and the other plug is for the TV under repair.

No gratification tonight it is. I'll bring a variac home tomorrow, and look to purchase one soon. I had thought about using shrink tubing on the leads on the caps, thanks for the tip wa2ise. I hear you on the no space VintagePC, I live in a sub 900sq foot one room loft with my wife. She has been really suportive of my new obsession, there is no hiding anything when you have no walls.

I don't think it's a big priority to rush out and spend a bunch on a variac for your first restoration project. If your main concern is not frying your TV, a cheap dim bulb tester actually provides more protection. If your TV has a dead short, the bulb simply lights up, and no harm is done. With an un-metered variac, you can still burn up a power transformer while gradually increasing the voltage, a fact that I learned to my dismay some years ago. A metered variac lets you monitor current use while you increase voltage, of course.

Phil Nelson

No gratification tonight it is. I'll bring a variac home tomorrow, and look to purchase one soon. I had thought about using shrink tubing on the leads on the caps, thanks for the tip wa2ise. I hear you on the no space VintagePC, I live in a sub 900sq foot one room loft with my wife. She has been really suportive of my new obsession, there is no hiding anything when you have no walls.

http://www.audiokarma.org/forums/images/icons/icon3.gif Why not make a wall of vintage TVs? Two birds with one stone :D

I didn't know there was such a thing as an un-metered variac. Then again what I don't know could fill a ocean :).

Update.
Brought home a variac and fired her up... No vertical deflection. I've now replaced all of the paper, multi stage cans, and electrolytics in the chassis (as far as I know). Time to move on to other trouble shooting. Any suggestions on where to start/where not to start?

The easiest place to start is with the vertical deflection coils (the ones on the neck of the CRT) - check them for continuity with a multimeter. If they're good, then I'd start looking for open or shorted resistors. A complete lack of deflection means a total failure somewhere...

Someone with a service manual might be able to point you in a more specific direction, but this is usually a good start for anything of this age. The carbon resistors tend to go high when exposed to a lot of moisture and cause all sorts of problems.

After you check the deflection coil, check R3, the vertical linearity control and R4 the vertical size control.

I assume you've already checked V13 the 6C4 and V14 the 6V6.

The way they've drawn the alternate circuits is confusing to me and I'm not sure where this section is getting it's B+.

I might have to pull my chassis and see what they really did.

John

"The easiest place to start is with the vertical deflection coils (the ones on the neck of the CRT) - check them for continuity with a multimeter."

Forgive my new guy ignorance but I don't know how to do that. I know how to check continuity with a meter but I'm not sure where you're suggesting I check. Could you elaborate on that some more for me?

"After you check the deflection coil, check R3, the vertical linearity control and R4 the vertical size control.

I assume you've already checked V13 the 6C4 and V14 the 6V6."

I've tested V13 and V14, they both check good. I've also adjusted R3 and R4 to no avail.

"I might have to pull my chassis and see what they really did."

Wow! You guys are so helpful here it's hard to believe. Please don't go that overboard for me yet. Let me do some due diligence of my own before we get to that point.

"
Forgive my new guy ignorance but I don't know how to do that. I know how to check continuity with a meter but I'm not sure where you're suggesting I check. Could you elaborate on that some more for me?


Certainly - I had to start somewhere too, so I know how it feels :) But, we're always happy to explain if you don't understand. I suspect the terminology we throw around doesn't help either...

If you look at the back end of the picture tube itself, you have the end that is wired up to the rest of the set, where the guns are. Moving forward towards the wider [bell] area of the CRT, you may encounter some rings with a bunch of tabs on them [purity magnets]. You won't need to touch those at this point. Further towards the bell, around the part where the tube begins to widen, will be a cone-shaped form [the deflection assembly, AKA the yoke]. This contains the coils of wire that the set uses to move the beam of electrons within the tube. One pair of coils is for the horizontal deflection of the beam, the other pair is for the vertical deflection.

(from the picture in the first post, yours appears to be boxed in in that metal cage that rises up from the main chassis).

Essentially what you want to do is find where those are wired to the rest of the set, and use those points to test each of the vertical coils in the deflection assembly for continuity. If it's closed in, you can't tell which leads go to which coils, so you'll have to go by the schematic. I don't have one on hand, so perhaps another member can tell you exactly where they are. You should be able to locate them by wires running to the vicinity of the vertical components just mentioned (R3, R4, V13, V14).

If you get an open reading on one of them, then there's a break in that coil, and you've found your problem. If not, then the problem is somewhere else... and hopefully it is, because coils aren't exactly easy or fun to repair.

Apologies for the wall of text, but it'll have been worth it if you learned something, and my job will be complete for today :)

Wow! You guys are so helpful here it's hard to believe. Please don't go that overboard for me yet. Let me do some due diligence of my own before we get to that point.

It's what we do here. Everyone was really helpful while I was restoring my Fleetwood console, and some people go above and beyond to help you. I guess we are dedicated to preserving these sets too much...

From what I can tell there is continuity across the coils. I looked at the schematic and I think the areas I pointed to in yellow is where to test.

http://farm3.static.flickr.com/2363/5708994942_82ab4c205c.jpg

I pointed to those leads in yellow below and there is continuity across those two leads. For some reason the wire on the output side of the transformer is soldered on a "landing strip"(I'm not sure if that is what you really call it but that is what I came up with). Maybe it's so you can test things easily, it certainly did make it easier for me.

http://farm4.static.flickr.com/3641/5708428957_d0c8f076c8.jpg

Could the next step be firing the set up and testing voltage out of the vertical output transformer(T4)?

For some reason the wire on the output side of the transformer is soldered on a "landing strip"(I'm not sure if that is what you really call it but that is what I came up with).
Could the next step be firing the set up and testing voltage out of the vertical output transformer(T4)?

Terminal strip.

Anyway, be careful with the vertical output tube plate, when it's working normally it has pulses about 1 to 2KV tall.

Before firing up the set, check that you have continuity on the primary of the vertical output transformer. Likely a few hundred ohms. Oh, on the yoke, getting continuity across the secondary either tells you the yoke has no opens or the secondary has no opens. Or both have no opens. You'll have to disconnect a lead on one of these to tell for sure.

Besides T4, you should also check for continuity on both the primary and secondary of T2 in the vertical oscillator. That one will be easy because you won't need to disconnect anything.

R3 is in the cathode of the vertical output and sees quite a bit of power which is hard on it. You should check to see that it has the correct resistance.

R4 supplies the plate of the oscillator and could be bad too, but it doesn't see as much power.

You might need to try substituting the 6C4 also even though it tests good. It might have too much grid leakage which might not show up on your tester.

John

T4's secondary reads spot on at 7.5 ohm. T4's primary which is supposed to read 700 ohm is reading twice that 1.4 k ohm.
T2's secondary which is supposed to read 1.3 k ohm is reading 1.4 k ohm. I'm assuming that is well within accepted tolerance levels. T2's primary is supposed to read 160 ohm. It is reading wide open.
R3 is good to go at 5 k ohm and adjusts as I turn the control.
The tester that was used to test the 6C4 had a leakage detector and it tested good there to.

So it looks like my problem is T4 and T2? Are those parts that one can find?

T2's primary is supposed to read 160 ohm. It is reading wide open.


So it looks like my problem is T4 and T2? Are those parts that one can find?

Sometimes the open happens at the spot where the enamel magnet wire is soldered to the lead wire. The old rosin sometimes corrodes the wire, causing the break. You could dig into the outer paper tape wrap to see if that might be the case. At this point the transformer would be trash if that's not the cause anyway, so nothing lost.

As for the output primary showing twice the resistance listed, well sometimes the schematic services have errors. Or the manufacturer made a production change. But T2's primary being open would kill the vertical. So pay that more attention.

Vertical transformers are somewhat similar to audio transformers, and also power transformers. Getting the turns ratio close enough would be trial and error, also getting the phasing correct is important. I don't know what turns ratio and impedances would be correct, or what would be close enough, so it would look like black magic... :scratch2:

Sometimes the open happens at the spot where the enamel magnet wire is soldered to the lead wire. The old rosin sometimes corrodes the wire, causing the break. You could dig into the outer paper tape wrap to see if that might be the case. At this point the transformer would be trash if that's not the cause anyway, so nothing lost.

As for the output primary showing twice the resistance listed, well sometimes the schematic services have errors. Or the manufacturer made a production change. But T2's primary being open would kill the vertical. So pay that more attention.

Vertical transformers are somewhat similar to audio transformers, and also power transformers. Getting the turns ratio close enough would be trial and error, also getting the phasing correct is important. I don't know what turns ratio and impedances would be correct, or what would be close enough, so it would look like black magic... :scratch2:

It's a blocking oscillator. I wonder if they rely on the core saturating? Sams only gives a Majestic part number for it so it might be difficult to find a replacement.

I think your point about the connection at the lead is a good one. I've seen that a couple of times. Refresh my memory. The primary is usually the inside winding isn't it?

I cut through the transformer in haste and cut too deep totally screwing up the winding so I don't know if it was the leads or not. I did pick up a new vertical block oscillating transformer to replace it though. The impedance on the primary and secondary are lower than the original but I put it in and I'm going to hope it'll oscillate. I may have to tweak the circuit with resistors inline with the new transformer to make it linear but I'm crossing my fingers it'll be ok as is.

http://farm3.static.flickr.com/2138/5711493830_14683bfbf5.jpg

Again I don't have a variac at home so I'll have to wait until tomorrow to fire it up and see what how I did.

Sadly, if it doesn't work, adding resistors won't help- the transformer's magic comes from the # of turns of wire inside, not from the resistance of the coil; less resistance probably means fewer turns, unless the wire gauge is thicker than the original. (if you add a resistor, you make an RL circuit which behaves very differently from a coil by itself)

Also, if you can get replacement "magnet" wire [copper wire coated in enamel] of the same thickness as that of the original transformer (a yoke from a crap modern tube TV is a great place to get some), you could always give re-winding it a shot. It requires some patience and finesse, but it couldn't hurt to try if you can't get a good replacement for a reasonable price (i.e. reasonable hourly pay for how long you spend to wind your own), or are up for a challenge. It seems daunting, but it's not excessively difficult to try.

To do that, the two magic numbers you need are a) the # of coil turns, and b) the total length of wire. Both of these can be obtained while you unwind the original. As pointed out before, you also need to pay attention to the polarity (winding direction) of the original. If you can match the winding pattern of the original, even better! Note that if A number of turns does not use near B amount of wire then something's wrong and you need to try again, unless it's because you use a different winding pattern.

[I managed it with just matching the length of wire and winding pattern in an oscillator coil for my Fleetwood console (wire was ripped beyond repair, so I couldn't count turns and had to lay the pieces end to end to get length), and it worked... but I don't doubt a TV circuit is much more finicky, so YMMV]. I'd be happy to offer more details if you have questions... but no guarantees since I've only re-wound one coil myself, and that may just have been dumb luck!

I looked in my Merit catalog and they do list a replacement. It's an A-3003.

The A-3003 has a turn ratio of 1:4.2, the A-3006 that you have is 1:3.5.

www.oldradioparts.com has the A-3003 for $7.00. They have a $25 minimum order.

John

I cut through the transformer in haste and cut too deep totally screwing up the winding so I don't know if it was the leads or not. I did pick up a new vertical block oscillating transformer to replace it though. The impedance on the primary and secondary are lower than the original but I put it in and I'm going to hope it'll oscillate. I may have to tweak the circuit with resistors inline with the new transformer to make it linear but I'm crossing my fingers it'll be ok as is.

http://farm3.static.flickr.com/2138/5711493830_14683bfbf5.jpg

Again I don't have a variac at home so I'll have to wait until tomorrow to fire it up and see what how I did.

but I put it in and I'm going to hope it'll oscillate.

If it doesn't oscillate swap the leads on either the primary OR the secondary, but not both.

Tried the transformer and got deflection!
http://farm3.static.flickr.com/2049/5718843008_4b548680c8.jpg
I'm emailing oldradioparts now to enquire about the correct transformer. Does any one else need any parts and want to go in with me to meet the $20 minimum order? I suppose I could always just give them $20 for the transformer instead of $7.

Tried the transformer and got deflection!
http://farm3.static.flickr.com/2049/5718843008_4b548680c8.jpg
I'm emailing oldradioparts now to enquire about the correct transformer. Does any one else need any parts and want to go in with me to meet the $20 minimum order? I suppose I could always just give them $20 for the transformer instead of $7.

You might look at his book and magazine section. You might be interested in some of the TV related ones.

It might be a while until I get my hands on the correct transformer so I was thinking about working on another problem I have with the set. The picture above was taken from a side angle so it's not as obvious as when you look straight on at it, but the picture is skewed to the right and not level. Can any one point me in the right direction towards a fix for that? Is that something that I can work on now, or should I wait until I have the transformer and a full height picture?

I found another Majestic on Craigslist in my area with the same deflection problem...I wonder if that is a common thing with these sets.
http://pittsburgh.craigslist.org/atq/2380646109.html

I'd hold off until you have a new transformer. I've seen a few other threads here where people had no vertical, and the line often looked a bit skewed.
Once you have an actual picture, you can then display a test pattern/grid to aid in adjustments, and do all of the convergence/purity stuff in one swoop.

If memory serves, you can "rotate" the picture by rotating the entire convergence assembly , as that will adjust the directions that the magnetic field deflects the beams.

There are usually a set of rubber wedges under the yoke to keep it from moving. You should mark their positions before you remove them, otherwise your centering will be off when you reassemble.

Here's an interesting read while you wait. This discusses purity adjustments on newer colour CRTs, but the principles behind it still hold. http://personalpages.tds.net/~rcarlsen/cbm/converge.txt

Besides Playthings of the Past, it might be worth contacting Moyers (http://www.moyerelectronics.com/Departments/Products/Vintage-TV-Parts.aspx).

I agree with VintagePC that you should wait until you have the vertical working.

I found a Stancor a-8122 locally, it's a vertical blocking oscillator transformer and has a turn ratio 1:4.2. Any one venture a guess if it'll work?

Should do the job. The turns ratio that is key to the magic that makes it work.

The only thing you may run into is the polarity (I suppose "phasing" is a better term since we're dealing with AC) - if it doesn't work, reverse the leads to one of the two sides and try again.

I don't know what would happen if you got the phasing out of sync here - If it's part of an oscillator, then it probably wouldn't oscillate, but since it's part of the vertical section, you might also end up with an upside-down picture :D (either way, it's a "safe" mistake - things won't go bang if it's wrong)

Vintagepc, I believe that this is not a color TV so it should not have purity or convergence adjustments.

Vintagepc, I believe that this is not a color TV so it should not have purity or convergence adjustments.

Whoops... 's what I get for posting/following several threads at once :)

Whoops... 's what I get for posting/following several threads at once :)
Heh.. I was kinda wunnerin' how the saga was gonna play out.


:smoke: oc(Bill)

Got the new transformer in the set and it gives deflection but not a full picture. It did bring the horizontal picture back to the center again. Even though it was not a full height picture it did for the first time look "correct." It might be because I could see scan lines for the first time, or because the picture was horizontally aligned, or it could just all be in my head. I did try adjusting the vertical hold control, the vertical linearity control, and the vertical size control, all to no avail. The transformer I used was a Stancor model a-8122. The turn ratio was 1:4.2. The primary and secondary impedance was a bit different on the replacement than the schematics showed on the original. The original was 160 and 1,300 and the replacement was 170 and 940. Could the transformer still be the problem or is it time to look elsewhere?
http://farm4.static.flickr.com/3552/5731654875_246a054379.jpg

Do the vertical controls do absolutely nothing to change the bar, or just that they don't get it to a proper height?

You don't mention it, but I assume you tried the lead swap on one of the transformer windings to check if the phasing was right?

If you did, it's probably time to start looking elsewhere; you've got "partial" vertical, as opposed to flat-out no vertical. That would suggest an out-of-spec component - time to start ohming out the resistors in, and before, the vertical section to see if any have gone high if you haven't already done so. If those all check out fine, then it can shift the focus back to the transformer; less of a headache that way than trying to source an exact match and finding it still doesn't work.

Are you able to borrow or access an oscilloscope? Those can come in handy when trying to figure out the problem, since the actual shape and tracing back of the waveforms can point to the cause relatively quickly (i.e. if the problem is caused by the vertical section, or the result of something before) ... but it can be done without.

Honestly I hadn't tried swapping the leads on the transformer. I guess my assumption was that if I wired it incorrectly that I would have no deflection at all. I'll try that first tonight. Thank you for taking the time to point out the painfully obvious, sometimes(hopefully THIS time) it helps.

Honestly I hadn't tried swapping the leads on the transformer. I guess my assumption was that if I wired it incorrectly that I would have no deflection at all. I'll try that first tonight. Thank you for taking the time to point out the painfully obvious, sometimes(hopefully THIS time) it helps.

Only because it happened to me when I re-wound the coil on my own radio. It didn't work well at first (though I could hear the output of a spark gap transmitter), but swapping the leads made a world of difference... so it's my mistake that you're learning from :)

Switched the leads on the secondary of the transformer and it had little effect. The vertical was the same size. The only difference was the image was again shifted to the right of the screen. I switched the leads back and the image was centered. I did take v13 to a shop to test it and it passed, although the guy admitted that he hadn't used his tester in quite some time so it may have been way out of calibration. There is another shop in town that I know I can trust if I take the tube there to test it so I may do that. He may be able to give some advice if it passes, and sell me another one if it fails. If every thing checks out there it's time to move on.

I do have access to a scope btw so if there is some tests I can run with it to narrow my search down before I start checking every capacitor and resistor that would be fantastic.

It would have been too good to be true if it had worked :)

I don't have a scope myself, but often the service manuals (Sams or otherwise) will have diagrams showing what the waveform should look like at various test points in the set.

If you don't have that, then perhaps someone more familiar with the waveforms that should be there can point you in the right direction for where to test and what it should look like.

If the v. controls do absolutely nothing, then I'd check those as well before going resistor-hunting... Sometimes dirty pots can cause weird problems.

Your Sams doesn't include model waveforms for the vertical circuits, unfortunately.

It does include a voltage chart. You can use a voltmeter to check voltages on V13 and V14 and then compare them to the voltages given in the chart. If you find one that's way off, you can then check the components in that neighborhood. Put one hand in your pocket when touching the voltmeter probe to anything on the live chassis.

Also double-check your previous work, making sure that you (or a previous handyman) didn't miswire a replacement capacitor, drop a blob of solder somewhere, or accidentally nudge some component so that it creates a short circuit. Even experienced restorers slip up every once in a while.

Phil Nelson

Put one hand in your pocket when touching the voltmeter probe to anything on the live chassis.


On top of that, if you have alligator clip leads or test leads, I like to connect one end to the test points before I power up the set so there's less danger of a slip-up with the probe- it's just clipping and unclipping the other end(s) safely away from the main part of the set.


Also, on top of the one-hand-in-the pocket rule: if you have electrically insulating rubber gloves, put on one (or both, if you can work with them) just in case you forget and do take that hand out of your pocket.

Safety first - Voltage hurts, current kills... and your body's resistance is futile. (Sorry for the pun... I'm terrible with them :D)

To the OP:

At this point, and if you still have access to the variac, you might consider trying this:

Disconnect both primary leads of the vert.out transformer and drive it directly with the variac. Granted it's a sine wave instead of sawtooth, but will tell you a lot. You should get very robust deflection, probably at around half to full line voltage. This will tell you the tranny and yoke coils are good, thereby proving the fault lies somewhere "upstream" of the tranny.

If the problem remains, it's gotta be either in the tranny or the yoke (like a shorted turn that won't show up on a resistance check). Now disconnect the yoke winding and drive it directly with the variac (starting from a low setting). If deflection comes up, the yoke is good and by process of elimination, the fault would be in the tranny.

Of course if the fault is "upstream" all bets are off. The first place i would look is the plate load resistor of the vert.oscillator, if you haven't already checked it. I can't see it since i don't have the schematic of your set, so this may not be applicable. But in many sets that resistor is a very common failure and worth bookmarking*. Its value goes 'waaay high due to being hammered by a high level pulse. Bill(oc)

*Germaine to all makes and ages of '50s-'60s tube sets.

To the OP:

At this point, and if you still have access to the variac, you might consider trying this:

Disconnect both primary leads of the vert.out transformer and drive it directly with the variac. Granted it's a sine wave instead of sawtooth, but will tell you a lot. You should get very robust deflection, probably at around half to full line voltage. This will tell you the tranny and yoke coils are good, thereby proving the fault lies somewhere "upstream" of the tranny.

If the problem remains, it's gotta be either in the tranny or the yoke (like a shorted turn that won't show up on a resistance check). Now disconnect the yoke winding and drive it directly with the variac (starting from a low setting). If deflection comes up, the yoke is good and by process of elimination, the fault would be in the tranny.

Of course if the fault is "upstream" all bets are off. The first place i would look is the plate load resistor of the vert.oscillator, if you haven't already checked it. I can't see it since i don't have the schematic of your set, so this may not be applicable. But in many sets that resistor is a very common failure and worth bookmarking. Its value goes 'waaay high due to being hammered by a high level pulse. Bill(oc)

Awesome suggestion! Thank you so much, I'll try this as soon as I get in front of the set again.

BTW- What is The OP?

I think I need to back up and run a test that I don't think I did right before. I want to test the deflection coils to see if my problem is there. In the picture of the schematic below I tested continuity across the yellow wires. I'm not sure if that was right. I think I need to test across the red, and across the blue to test each coil. Can any one confirm that? If that is indeed what I need to do then my next problem is that I don't know how to test the two coils independently of each other. I apologize for leaning so hard on all of you to help me get this sucker up and running, but we all have to start learning some where I guess.http://farm3.static.flickr.com/2148/5743715110_1fd58f051e.jpg

Looking at your picture, what you'd want to do is as follows. This will ensure you've tested the coils:

1. Disconnect/desolder the ground connection at the lower yellow arrow. (this ensures you test the coils themselves and not an alternate current path - note the other yellow arrow traces through the transformer and also to ground, resulting in two possible paths for the current to flow when you measure any two points in that line.)

2. Measure across the blue arrows.

3. Measure across the red arrows.

4. Reconnect the ground connection from step 1.

It looks like you have resistors in parallel with your coils in the schematic. If that's the case, the resistance you measure should be 1/measurement = 1/(coil resistance)+1/(resistor resistance). Keep in mind the coil will have a fairly low resistance, so the reading is probably only a handful of ohms.

With both resistor values the same, the red and blue measurements should be identical.

If you measure anything different than expected, you'd need to disconnect one lead of the resistor to determine the culprit (coil or resistor)

Looking at your picture, what you'd want to do is as follows. This will ensure you've tested the coils:

1. Disconnect/desolder the ground connection at the lower yellow arrow. (this ensures you test the coils themselves and not an alternate current path - note the other yellow arrow traces through the transformer and also to ground, resulting in two possible paths for the current to flow when you measure any two points in that line.)

2. Measure across the blue arrows.

3. Measure across the red arrows.

4. Reconnect the ground connection from step 1.

It looks like you have resistors in parallel with your coils in the schematic. If that's the case, the resistance you measure should be 1/measurement = 1/(coil resistance)+1/(resistor resistance). Keep in mind the coil will have a fairly low resistance, so the reading is probably only a handful of ohms.

With both resistor values the same, the red and blue measurements should be identical.

If you measure anything different than expected, you'd need to disconnect one lead of the resistor to determine the culprit (coil or resistor)

I'm good on the points you mentioned above. My problem is that I don't know where on the actual set itself is in between the two coils. It makes sense on the schematic but I can't transfer that to the set.

Hmm... it might well be an inaccessible direct connection between the coils in the yoke itself. If that's the case, the best you can do for steps 2/3 is test across the yellow arrows. the result can indicate if coils are open. It won't indicate shorts because of the parallel nature of the circuit.

The AC/variac drive test mentioned above will give better information as to the state of the coils, since you get a visible result... If it does indicate a problem in the coils, the test I described would help narrow it down.

Hmm... it might well be an inaccessible direct connection between the coils in the yoke itself.
The connection is most always inside the yoke housing.
If that's the case, the best you can do for steps 2/3 is test across the yellow arrows. the result can indicate if coils are open.
Yep, but he's gotta disconnect one end, either the ground end as you suggested, or the top end. Doesn't matter which. While it's disconnected is a good time to also check continuity of the secondary winding of the transformer.
To the OP (original poster): is the capacitor across that winding (shown with dotted lines) actually in the set? If so, have you replaced it and/or verified that it's not shorted?
oc

Yep, but he's gotta disconnect one end, either the ground end as you suggested, or the top end. Doesn't matter which. While it's disconnected is a good time to also check continuity of the secondary winding of the transformer.
To the OP (original poster): is the capacitor across that winding (shown with dotted lines) actually in the set? If so, have you replaced it and/or verified that it's not shorted?
oc

Looking at the schematics I see that both coils are 2200 ohms. If I meter on my yellow arrows am I correct in thinking that it should be 4400 ohms?
The secondary of the transformer is good.
The third question about the capacitor across the winding in the schematics I cannot answer. I didn't see that before you mentioned it. It says that it's 75mmf, but it's not listed in the part list. Could that also be located inside the yoke housing?

Looking at the schematics I see that both coils are 2200 ohms. If I meter on my yellow arrows am I correct in thinking that it should be 4400 ohms?
Not quite - the schematics show resistors in parallel with those coils, and those resistors are each 2200 ohms. (Look at the horizontal coils - there's no resistance marking/parallel resistor).

The only time you'd read ~4400 ohms is if both coils are open.
If you read ~2200, one coil is open.
If you read something closer to zero, then the coils are probably OK (but you can't infer anything about the state of those resistors - see my parallel resistance calculation in the previous post).

BTW, if you can see those two resistors sticking out of the yoke or anywhere on the chassis, it gives you some test points for your red/blue arrows.


The third question about the capacitor across the winding in the schematics I cannot answer. I didn't see that before you mentioned it. It says that it's 75mmf, but it's not listed in the part list. Could that also be located inside the yoke housing?

It's possible, but doubtful. The easiest way to find it is to carefully trace the entirety of that vertical deflection line which your arrows point to and try to locate it. If you can't find it, you can do a test to see if it's there- disconnect BOTH ground points at each end of the line, and apply a few volts (no more than 20) AC to the line. (it will float, since it's not grounded at either end).
Then, see if some AC appears on the chassis ground. If so, that capacitor is hiding somewhere and passing AC (or it might be shorted). If not, it's probably not there.

Also, look at the connections running in to the yoke - there should be 4, two for vertical, and two for horizontal. (You may see only 3 if the lower ground is directly accessible from the yoke.
If you see more/fewer, it may indicate additional components have been hidden... try to trace them on the schematic to find out what those wires do.

Since the 75mmf is inside of the dotted line for the deflection yoke it would seem that it is part of the yoke. Unless I'm looking at the wrong 75mmf.

Since the 75mmf is inside of the dotted line for the deflection yoke it would seem that it is part of the yoke. Unless I'm looking at the wrong 75mmf.

My understanding is we're talking about the one above his upper yellow arrow. The one you refer to is part of the horizontal circuit, whereas we're diagnosing the vertical :)

Old Coot- Are you referring to the capacitor just above the dotted lines indicating the yoke in my picture? The schematics say that it's C70 and rate it at .25mmf at 200v. The thing is I can't find it on the schematic pictures of the top and bottom of the set that indicate where everything is. Jeyurkon maybe you can confirm that?
The schematics make me think that the capacitor would live at the end of the right hand yellow arrow in the picture below.
http://farm4.static.flickr.com/3641/5708428957_d0c8f076c8.jpg
As you can see there is nothing there but a termination point for the wire coming from the secondary of T4 and from the vertical coils. I had mentioned this in an earlier post and postulated that maybe it was just there just to make my job easier. Is it possible that it is just missing from the set? That seems improbable to me.

To what are those two little "domino" looking things connected? (hiding behind the big resistor that's dead center.). Those are mica capacitors, and it looks like they have one lead on the left-hand connector to which an arrow points.

Also, if that orange-brown square with three leads coming out of it is connected to anything relevant, beware that those are usually a package containing a resistor and capacitor network. It doesn't look like it's attached, but just something to keep in mind. Some schematics show the separate components, some show a "magic box", and others will show the internal components outlined with a dashed-line box.

It's also possible that that capacitor is hiding somewhere in the yoke, especially if there's a nearby accessible ground point to which they could run it... It could well be bridging BOTH deflection coils to the ground connection on their other side.

Since most capacitors short on failure (unless they're special line safety caps), the AC test I mentioned will show if it's present regardless of condition... and at least knowing that eliminates some of the guesswork.

The parts list has an asterix next to C70. "Not used in all models." Also a note symbol and dotted line in the schematic.

Phil Nelson

The parts list has an asterix next to C70. "Not used in all models." Also a note symbol and dotted line in the schematic.

Phil Nelson

We'll there you have it. I guess my model is part of the exception.

My understanding is we're talking about the one above his upper yellow arrow. The one you refer to is part of the horizontal circuit, whereas we're diagnosing the vertical :)

Thanks, that explains my confusion. That one is actually 0.25 uF, or would be if it were used.

I should have paid more attention and noticed that the discusion was about the vertical.

I took an early day at work to spend some time on the set tonight. I also read through this entire thread a couple of times to come up with a game plan of tests for this evening. Here is what I'm thinking.#
I'm going to recheck the vertical height control selector.#
I'm going to check voltages on v13 and v14. I will connect my lead clips to the set and to my meter, then fire the set up for a measurement. After taking a measurement I'll remove power from the set and move on to the next voltage measurement.#
I'm going to disconnect both primary leads on my new t2 and connect them to the two leads on my variac. I'll fire the set up and turn up the variac to line voltage or robust deflection, which ever comes first.#
If deflection does not occur I will move on to OC's next suggestion of driving the coils directly with the variac. On this test I'm a bit hazy on. There is only one lead from the yoke on the vertical side. What would I do with the other lead on the variac?
After completing those test if I have time I'll move on to more.#

There is only one lead from the yoke on the vertical side. What would I do with the other lead on the variac?

The other side of the vertical is connected to ground according to the schematic (most likely chassis ground somewhere.)

you _SHOULD_ be able to connect the neutral side of the variac output (Be careful that you do really have neutral!) to the chassis, and then the HOT side to your coil wire.

HOWEVER, before you do that, double-check that your chassis is actually grounded or connected to line neutral. If your set has the possibility of a "Hot" or floating chassis voltage (i.e you do NOT read close to zero volts when measuring voltage from chassis to neutral in the wall plug), DO NOT DO THIS - it could trip your breaker!

Since you know the transformer is good though, if driving it with the variac produces no deflection, you can be almost certain the coils are the problem... and the test you're unsure about will produce little extra information.

Taking off early to spend time on the set turned into run errands time :sigh: I was able to do a voltage test on V13 and V14, however.
My results:
V13 according to the schematics should read- Pin 1: 170 to 40VDC. Pin 4: 6.3VAC. Pin 5:170-40VDC. Pin 6: -40 to -2.4VDC.
V13 actual readings- Pin 1: 51 to 20VDC. Pin 4: 7.5VAC. Pin5: 51 to 20VDC. Pin 6: -1.21 to -.97VDC.
V14 according to the schematics should read- Pin 3: 260 to 230VDC. Pin 4: 260 to 230VDC. Pin 6: 215VDC. Pin 7: 6.3VAC. Pin 8: 30 to 8VDC.
V14 actual readings- Pin 3: 350 to 300VDC. Pin 4: 445 to 230VDC. Pin 6: 295 VDC. Pin 7: 7.5VDC. Pin 8: 49 to 12VDC.

V14's readings are a bit high, but could those be within tolerance? V13's readings are low enough that I can't imagine they would be within tolerance. V13's readings on pins 3,4, and 8 change with the adjustment of V4a(the vertical size control). Schematics call for resistance of 2.5meg which is right what it metered to. I mentioned before that I wanted to change V13(a 6C4) but I haven't done that yet.

I would check resistors around and downstream of the oscillator, R65 and R66 especially, also R67 and R68 while you're in the neighborhood. You have partial deflection, suggesting that your oscillator is working somewhat, but its sawtooth is attenuated. You have already replaced obvious capacitors in that area. There ain't much left but resistors, so I would check those to eliminate 'em from the equation.

Also, C48 is the coupling cap for the oscillator. With a value of 4700 pf, I suppose it is a mica, but micas do croak sometimes.

Phil Nelson

I tested R65-R69 previously and they all passed. I'll look into C48.

Any chance somebody could post the schematic of the entire vertical section? I re-read the thread to see if I'd missed it, but dint see it. oc

Here ya go.

http://antiqueradio.org/art/temp/Majestic1600.jpg

Grid and plate voltages of the oscillator tube are low. It would be interesting to sub that tube, or even look at things upstream.

Phil Nelson

Arr. Now we're cookin'. First assuming the output transformer and yoke coils have proved good, I wouldn't worry about the oscillator just yet, but first prove whether the output stage is working or not. Just inject some AC at the control grid (pin 5) of the 6V6. No need to disconnect anything, since everything 'upstream' is high impedance and DC-isolated by C50. Just run a jumper from pin 7 (heater) to pin 5. That'll put 6.3VAC directly on the grid, which should give a few inches of deflection (and it should vary somewhat with the linearity adjustment). If it does, that would indicate the output stage is working, and the failure lies upstream in the osc. area.
oc

Arr. Now we're cookin'. First assuming the output transformer and yoke coils have proved good, I wouldn't worry about the oscillator just yet, but first prove whether the output stage is working or not. Just inject some AC at the control grid (pin 5) of the 6V6. No need to disconnect anything, since everything 'upstream' is high impedance and DC-isolated by C50. Just run a jumper from pin 7 (heater) to pin 5. That'll put 6.3VAC directly on the grid, which should give a few inches of deflection (and it should vary somewhat with the linearity adjustment). If it does, that would indicate the output stage is working, and the failure lies upstream in the osc. area.
oc

Should I get a few inches of deflection total? or a few inches more deflection than I have already, which is already a few inches?

Should I get a few inches of deflection total? or a few inches more deflection than I have already, which is already a few inches?
A few inches total, since all the grid will be "seeing" is the 6.3VAC. Also, before doing this, try grounding pin 5. You should get a flat line. Then do the 6.3 jumper trick. How does this deflection compare with what you already had?

OC- Grounding pin 5 did indeed give me a flat line. Jumping pin 5 to pin 7 gave me a lot of deflection as you can see below. The two pictures below display the range I got from adjusting the linearity adjustment.

http://farm4.static.flickr.com/3274/5761213969_09f1bc924c.jpg

http://farm3.static.flickr.com/2229/5761757414_67bdf6394b.jpg

Very exciting to see something different! Also kind of interesting to see 60hertz through the second picture, which I only noticed on the picture and not looking at the set itself. Thanks so much to all of you for all the help again, I'm having such a blast with this!

:banana::banana::guitar:Hey cool. Now in one fell swoop you've proved that the output stage, transformer and yoke are all good, and the failure lies back in the osc. area. Basic isolation technique 101. :D

I spent some time looking over the schematic to get familiar with things down stream from the vertical output stage. I traced each connection from point to point on the schematic and on the set itself and found my first mistake. I had connected the secondary of T2 to the wrong place. I connected it correctly and got this.
http://farm6.static.flickr.com/5186/5777530382_93f5b52535.jpg
I also found the the ion trap was a bit out of place so I tried to align it as much as I could by site. I also adjusted the vertical controls to see if I could get an aligned picture but the picture above is as good as I could get it. I'm not sure if you can tell by the picture but the bottom of the picture is brighter than the top, and the left hand side of the screen is brighter than right. Any ideas on where to head next?

Looks to me as though something is clamping the vertical sweep wave... i.e. it's rounded off on the bottom instead of a nice sawtooth.I'd be tempted to say it's a passive component (resistor, capacitor) that's the culprit, but if that's the case, you'd see it at the top of the sweep too.

Does anything happen if you adjust the vertical centering control, and if so, can you bring the top edge of the raster in to view?

I don't know where the vertical centering control is on my set. I don't see mention of it in the schematics.

....I also adjusted the vertical controls to see if I could get an aligned picture but the picture above is as good as I could get it. I'm not sure if you can tell by the picture but the bottom of the picture is brighter than the top... Any ideas on where to head next?
Try jumping a known-good electrolytic across C1 (the 100mf one going to the cathode [pin 8] of the 6V6). That's exactly the effect you'd see if that cap were open. oc

The bottom is brighter than the top because the vertical linearity is way off. It could be an adjustment, or a symptom of another problem.

The bottom is brighter than the top because the vertical linearity is way off.
That's correct.
It could be an adjustment, or a symptom of another problem.
An open (or absent) electrolytic (C1) on the cathode of the output stage will cause severe non-linearity with insufficient sweep at the bottom. I'm wondering too if the problem isn't related to T2 (the coupling xfmr.) being different from the original.. and also if this difference is gonna cause the vert. frequency to be off. oc

I don't have another 100uf cap to replace C1B, nor do I have a capacitor tester. What I did do was fire the set up and take a visual check, then remove the cap that is in place and fire it up again. There was no change at all in the picture. I'll get another 100uf cap and try swapping it in.

There was no change at all in the picture. I'll get another 100uf cap and try swapping it in.

Seems to confirm what everyone says... Fingers crossed once you get that replacement! :)

New cap same problem :(. Might R3 be the problem? I've tested it for impedance but could it fail in another way? I'm going to try again to get the real replacement for T2 to eliminate that from the equation also.

New cap same problem :(.
Well doggone. Did you connect the + end of the cap directly to pin 8, and the other end to ground? (Some foreign-sourced electrolytics have an arrow pointing to the [-] end of the unit, which can trick you as to which polarity it's signifying.)
Might R3 be the problem?
Not likely if it measures (approx.) 5K and shows no dead spots or drop-outs throughout its rotation.
I'm going to try again to get the real replacement for T2 to eliminate that from the equation also.

R3 reads 5k on the high side and just a couple of ohms on the low side. There are no dropouts or dead spots in the rotation. C1B used to connect to pin 8 with a wire. I removed the wire since I was no longer using a multi stage can and now have the electrolytic directly on pin 8 and the negative right to ground. Here's hoping a new T2 will be the answer.:worried:

If you have the proper resistors to match the new T2's resistance to the original, you can try that too. I doubt it would work, but if it does, it might save a few bucks on trying to locate a matching part elsewhere.

New transformer same problem :headscrat. I will return to the schematic for component by component tracing soon.

Sounds like it's time to break out the scope :)

Tracing waveforms can get you a good idea of where the problem lies. Do you have a reference of what they should look like? (Usually in a Sam's)

Also, if you have substitute tubes, it may be worth trying those too. Some sets drive them to their design limits, and the result is a set that works perfectly with one tube, but not another that is slightly out of spec. Both tubes will still test good, of course, so the easiest way to find this problem is what's called the "tube roll" (swapping tubes in the problem areas with another one).

the result is a set that works perfectly with one tube, but not another that is slightly out of spec. Both tubes will still test good
I have found that to be the case with oscillator tubes, especially. Sometimes I have had to swap in several horizontal oscillator tubes before finding one that the TV "liked."

Speaking of oscillators, are the voltages on V13 still as far off as before?

Looking at waveforms with a scope seems sensible. This schematic doesn't give models, but you could start by looking at the grids of V13 (oscillator) and V14 (output) and posting photos of what the scope traces look like there.

Phil Nelson

New transformer same problem :headscrat. I will return to the schematic for component by component tracing soon.
Well tarnation. Just out of curiosity, what voltage are you getting at the low/wiper end of the vert. size control? oc

**I forgot about the recent progress and was commenting about an earlier state.** :o

Um.. just to reiterate what was suggested back in post# 62, the plate load resistor of the
V.oscillator is a very common failure point and should be double checked if you haven't already done so. Now that we got the schematic to look at, that would be R66, 470K (half a megohm +/- 10% or so).

And does the V.size control (R4) measure correctly at 2.5 meg or so?

How about the voltage at the bottom of R4? Since it's supplied from B boost, it should probably be somewhere around 400-450 V.

oc

I think I might have found my answer... Well let's all cross our fingers and hope so :yes:. Being a rookie at this restoration business I mistook black beauty capacitors for resistors. I missed five of them in the set including C49- the vertical discharge cap. I have the replacements on order and I'll let you know if that's the solution.

R66 is good to go btw.

Sounds promising. They look pretty but are evil.

But they're so pretty!

I think I might have found my answer... Well let's all cross our fingers and hope so :yes:. Being a rookie at this restoration business I mistook black beauty capacitors for resistors. I missed five of them in the set including C49- the vertical discharge cap. I have the replacements on order and I'll let you know if that's the solution.

R66 is good to go btw.
Yeah, C49 could sure as heck be pulling down the 6C4's plate voltage if it's leaky. Just for the heck of it, try disconnecting C49 and see if the plate voltage goes up. That resistor in series with it (R67), what does it measure? It's kinda hard to read from the print but it looks like it says 8K.

With C49 disconnected, what happens to the sweep?

oc

Yeah, C49 could sure as heck be pulling down the 6C4's plate voltage if it's leaky. Just for the heck of it, try disconnecting C49 and see if the plate voltage goes up. That resistor in series with it (R67), what does it measure? It's kinda hard to read from the print but it looks like it says 8K.

With C49 disconnected, what happens to the sweep?

oc

I know R67 reads good, I checked that off of my list. I'll disconnect C49 and and report results but I can't do it tonight. I've already started :beer: and I made a rule, no TV time after beer :D.

Aww, but that is when it is the most fun! Last new years(or was it christmas) I had a couple, and droped a Color chassis on my foot. It took me a while to realize that it cut me!... the little bugger.

Back when I encountered my first set with those bumble bee caps(it was a zenith transoceanic) I made the exact same mistake. To this day it still has those caps in it.

Tom C.

After you get the C49 thingy sorted out, take another look at the 6V6 output stage and see if it's "version 1" or "version 2".

With the revisions shown in the schematic, the output stage itself has seen a fair bit of engineering fudgery, probably to optimize linearity.

In "version 1" the plate and screen (pins 3 and 4) were simply strapped together. Kind of unusual.

In "version 2" the screen is supplied from B boost (again kinda unusual), through added-in resistors R96 and R97. Cap C69 is added from the plate to screen, probably to tailor the waveform. And bypass cap C71 is added to filter the boost line.

If your set has "version 2", those two caps should definitely be replaced if not already. And the two resistors checked for value. oc

Because I'm not afraid to look like a rookie here, and in the hopes of teaching some one else, I'm going to tell you what I didn't do. I didn't test the tubes in this set (except the two vertical tubes, and even then I don't think the tester was good) until today. I know some of you will be thinking :wtf:, I am thinking :wtf:. My new rule is tubes will be tested before I even begin recapping. Ten tubes were shot... 10! I came home to replace the tubes in question and found two things. #1- my set uses V10 and I don't have a 6AT6. I had a 6AV6 left after replacing all of the other tubes. I'm not sure if I had a mix up at the shop when I was replacing tubes, or if a 6AV6 was in V10 in the first place. At any rate I simply left V10 out and fired the set up. #2- When I give the set more than 90volts I start to hear a sound in the high voltage cage that I don't like. The sound get worse as I cranked voltage higher. It kind of sounds like a very faint snap...snap...fsst...crackle...fsst..snap...crackl e. It could just be a different sound and I'm paranoid but it sounds like something is eating itself. I don't know how to test such a thing as I can't tell exactly where it's coming from. I'd rather not "test" by waiting until what ever it is to finish eating itself and whatever other components around it that it wants to take with it. Any thoughts on what the noise could be?
BTW the vertical is now full height.
Sorry to all of you here for wasting trouble shooting time by not completing step one.

The 6AT6 and 6AV6 are interchangable. if the 'V6 is good just leave it in.

Do you smell anything burning, or smell ozone? Is the aquadag (conductive coating) on the CRT securely grounded?

Hey, you didn't waste anybody's time so don't feel bad :) We all enjoy the heck outa this stuff no matter whut.

Is the aquadag (conductive coating) on the CRT securely grounded?
Where is this connection?

I may not have wasted any ones time, but it was a forehead slapper for me that's for sure. It sure has been a learning experience on my first set.

When the CRT bell is coated with aquadag (black graphite-looking stuff), there is usually a pair of thin wiry springs (sometimes one spring) that push onto it when it is fully installed. These connect to chassis ground, often through the metal yoke housing.

If the sound is a sort of faint hiss or fsst noise, it might be corona (high voltage arcing) somewhere inside the high voltage cage. Did you ever open that cage and clean the stuff inside? It's often covered with very fine, sooty dust. Rubbing alcohol cleans it off easily.

If the inside of the cage is clean, you could open it up and briefly power up the set with the room dark. HV arcs look bright blue or blue-white. If you see any, note the location and power down immediately, then investigate.

Phil Nelson

When the CRT bell is coated with aquadag (black graphite-looking stuff), there is usually a pair of thin wiry springs (sometimes one spring) that push onto it when it is fully installed. These connect to chassis ground, often through the metal yoke housing.

If the sound is a sort of faint hiss or fsst noise, it might be corona (high voltage arcing) somewhere inside the high voltage cage. Did you ever open that cage and clean the stuff inside? It's often covered with very fine, sooty dust. Rubbing alcohol cleans it off easily.

If the inside of the cage is clean, you could open it up and briefly power up the set with the room dark. HV arcs look bright blue or blue-white. If you see any, note the location and power down immediately, then investigate.

Phil Nelson

I remember reading this from your 630ts. When I first heard the sound this is what I thought of so I took a look at the area through the bottom of the set with the lights out and couldn't see any arcing. I'll try looking at it from the top of the set tomorrow and see if I can't pinpoint any arcing.

Found the source of the noise. It is V18, the high voltage rectifier. The base of the tube is sparking bright light blue. Could this be a bad tube itself, or possibly a fault elsewhere causing the problem? R89 and R95 are both reading right on.
I'm sorry to be such rookie but I'm still don't quite get the ground connection for the aquadag. I've google searched the spring connections and saw a couple of examples but my set doesn't have anything like that that I can see. The only connection that I can see is a rigid wire connected to ground with a u shape around the high voltage wire. Is this supposed to be making a connection for the aquadag, or is it just to hold the high voltage lead in place? I've tried to show as much as possible of the tube in the three pictures below.
http://farm4.static.flickr.com/3009/5850379347_d5be2bed5c.jpg
http://farm6.static.flickr.com/5065/5850929116_69fe9c32a4.jpg
This next picture you can see the high voltage lead and the wire I mentioned with it.
http://farm3.static.flickr.com/2729/5850377753_80d76cf28c.jpg

Huh. By golly that tube does not have an external aquadag coating. That wire around the HV lead has no electrical function, it's just a mechanical support.

At least you've located what's doing the arcy sparky thing.

oc

It doesn't look to me like your CRT has any aquadag coating on it - not all do. I bet there's a high voltage capacitor next the the rectifier tube that does the filtering.

The arcing could be caused by component leads or wires coming too close to the base. I recently worked on a Motoorla that had bad arcing caused my a wire coming too close to the rectifier. All I had to do was move it out of the way.

Did you do any work around that area ?

xxxxxxxxxxxxxxxx

Did you do any work around that area ?

I did not. I'm almost positive that the arcing is happening inside the tube itself. I'll fire the set up one more time and be sure.

Did they make a set with a glass crt that did not have a ground going to the chassis? Is there a door knob cap connected to the HV rectifier? If not I think you may have washed off the aquadag coating when you cleaned the crt.
From what I see in your pictures I do not see the aquadag coating.
Ed

There is a door knob cap at the base of the HV rectifier.

There is a door knob cap at the base of the HV rectifier.
That is the first time I have seen a set with a glass crt that did not have a aquadag coating on it.
Ed

The arcing is coming from inside the tube, I'm sure of it now. The picture is kind of hard to see because the room was dark but you can see the bluish glow coming from inside the 1X2. Am I right in assuming that this tube is no good?
http://farm4.static.flickr.com/3001/5850663347_3be16d1dfe.jpg

Yep, it has air in it and the HV is causing it to ionize. Replace it, and get that HV all the way to the screen!

That is the first time I have seen a set with a glass crt that did not have a aquadag coating on it.
Ed

I have several early rectangular 16" CRTs with no coating on them. I'm not sure why though. The datasheets state that they should.

I have several early rectangular 16" CRTs with no coating on them. I'm not sure why though. The datasheets state that they should.
That is interesting. Do your set's have a door knob cap connected to the hv rectifier tube? In A set with a metal cone crt the door knob cap goes to ground.
Wonder why are they using a door knob cap in a set with a glass crt instead of using the aquadag for a path to ground?
Ed

That is interesting. Do your set's have a door knob cap connected to the hv rectifier tube? In A set with a metal cone crt the door knob cap goes to ground.
Wonder why are they using a door knob cap in a set with a glass crt instead of using the aquadag for a path to ground?
Ed

Yes, they have doorknob caps. So do most of my 10BP4 and 12LP4 sets with grounded aquadag. I guess they wanted the extra capacitance. I think only my cheapo Motorolas rely entirely on the aquadag for HV filtering.

Yep, it has air in it and the HV is causing it to ionize. Replace it, and get that HV all the way to the screen!

Got a new 1X2 today but noticed that the old 1X2 was a 1X2A and the new one is a 1X2B. The old tube is on the left and the new tube is on the right. Are these interchangeable?
http://farm3.static.flickr.com/2632/5854716142_3d7cc72513.jpg
Here is the new tube installed and waiting for a higher intellect to give it the green light.
http://farm3.static.flickr.com/2785/5854162647_2c36b211cd.jpg

Yep, they should be interchangeable.

Take a look at the letter code specifications - the trailing letters indicate features of the tube. A/B/C are revisions that are backwards compatible, and there are a few others like GT, M etc. indicating glass tube, metal, and some other things.

http://en.wikipedia.org/wiki/RETMA_tube_designation

Fired the set up and got this.
http://farm4.static.flickr.com/3224/5855035164_5dbc78e17e.jpg
Fired her down immediately. Is this normal? Just a burn off process or a symptom of another problem?

Holy mackrel. Possibly a dead short either in the doorknob cap or from the 1X2 filament winding to ground. oc

That's a lot of bombardment, I'd look for a short. You can temporarily remove the doorknob and see if that cures it, you won't do any harm to the set.

Holy mackrel. Possibly a dead short either in the doorknob cap or from the 1X2 filament winding to ground. oc

Maybe that's what was wrong with the problem with the other tube.

Fired the set up and got this.
http://farm4.static.flickr.com/3224/5855035164_5dbc78e17e.jpg
Fired her down immediately. Is this normal? Just a burn off process or a symptom of another problem?

It can be a bit normal in POWER tubes... but you shouldn't see that in a rectifier. (Especially not that much- I assume that was a normal exposure.) Here's a 30 second exposure of the output tubes in my radio... and this was at a good volume for comparison.

http://vintagepc.site50.net/site/images/photos/small/IMG_1268.JPG

To echo the other folks, look for a dead short. Keep the old 1X2 on hand-- it might still be good!

(EDIT: Ninja'd: Maybe that's what was wrong with the problem with the other tube. )

--> Though I do have to admit, that _is_ a very nice blue colour to see for real. Cameras don't do it justice.

I'm sure glad my first project has had so many problems with it. Gives me more experience in what it's not supposed to look like on my future projects. :D

Honestly though, would you really have had as much fun, or appreciate the end result as much if you only had to replace a handful of caps? :)

For most of us nuts, the more challenging it is, the better - it's all that much more satisfying to wind your own coil and have it work than just drop in a generic replacement.

R89 and R95 both read good. C66 is the doorknob cab, it is not shorted and removing it still gives the same results when I fire it up. Other components in the area are B3 (horizontal size control), C64 (horizontal sweep coupling), and T3 (the flyback). Any other components I should look at? I'm off to work but I'll be home early to spend some time on the set tonight.

There's a quickie way to verify whether (or not) the fly is putting out. Remove the 1X2 and using a well insulated screwdriver, bring the metal tip of the screwdriver close to the plate cap connector. You should be able to draw a hefty RF 'air arc' a quarter to half-inch long onto the screwdriver. If you get the arc, that tells you everything 'upstream' is working.

I was thinking maybe a hard-leakage path from the 1X2 filament winding to ground mighta developed, based on your earlier statement of hearing a sizzling noise. Just for the heck of it (with the set off), using the highest ohms scale on your meter, measure from ground to the 1X2 filament winding. It should read infinity (open circuit). If it reads anything at all, it would indicate an insulation breakdown that's lugging down the HV.

oc

Perhaps the stiff wire that supports the HV lead going to the CRT has dug through the insulation and is shorting it out ?

Perhaps the stiff wire that supports the HV lead going to the CRT has dug through the insulation and is shorting it out ?

Good thought but not the answer.

There's a quickie way to verify whether (or not) the fly is putting out. Remove the 1X2 and using a well insulated screwdriver, bring the metal tip of the screwdriver close to the plate cap connector. You should be able to draw a hefty RF 'air arc' a quarter to half-inch long onto the screwdriver. If you get the arc, that tells you everything 'upstream' is working.

Simultaneously the coolest and most terrifying test I've ever done. It's a yes on flyback output.

was thinking maybe a hard-leakage path from the 1X2 filament winding to ground mighta developed, based on your earlier statement of hearing a sizzling noise. Just for the heck of it (with the set off), using the highest ohms scale on your meter, measure from ground to the 1X2 filament winding. It should read infinity (open circuit). If it reads anything at all, it would indicate an insulation breakdown that's lugging down the HV.

oc

Sorry for the ignorance but where can I measure/where is the filament winding on the 1X2?

One more thing. Even without the 1X2 in place I can hear the "voltage spitting" sound but unfortunately I can't get a visual on any arcing. I only fire the set up for a few seconds at a time, however, and even then not to full line voltage. If I can get confirmation that I can crank up to full voltage for a longer period of time- 15 to 20 seconds or so, maybe I can get a visual.

I did a little drawing (I know don't quit my day job!) of the area in question. It differs a little from the schematic. I'm not sure if the answer is in there but here it is.
http://farm6.static.flickr.com/5227/5857870426_f3de57398c.jpg

The schematic shows pins 5 & 6 connected to a loop on T3, the flyback transformer. That is the filament winding that Bill mentioned. Pin 8 connects internally to pin 5, so either of them could be used for this purpose. If the 486K resistor in your diagram is R89, then your hookup looks normal.

Do you see anything at all connected to other pins on the 1X2 socket? Pins 3 and 7 are not used for anything, so they would be free to use as tie points for unrelated stuff, although I don't recall seeing any such things on a HV rectifier socket before.

Phil Nelson

http://antiqueradio.org/art/temp/Majestic1600HV.jpg

My money is still on a shorted doorknob, if the filament winding on the flyback were arcing you'd likely see that as well as the intense glow from the rectifier. I say it's time to sub in a doorknob cap.

I thought he had the same problem when the doorknob cap was disconnected.

Phil Nelson

My money is still on a shorted doorknob, if the filament winding on the flyback were arcing you'd likely see that as well as the intense glow from the rectifier. I say it's time to sub in a doorknob cap.

Shorted to ground? It doesn't read shorted. I don't have a capacitor tester so I can only test if it's shorted.

I thought he had the same problem when the doorknob cap was disconnected.

Phil Nelson

It did.

Perhaps the stiff wire that supports the HV lead going to the CRT has dug through the insulation and is shorting it out ?
That's the very first thing I thought of too, until checking the schematic. If a burn-through happened there, it woulda zorched R89, the 470K resistor in series with the HV lead. He says R89 is OK though.

The schematic shows pins 5 & 6 connected to a loop on T3, the flyback transformer. That is the filament winding that Bill mentioned. Pin 8 connects internally to pin 5, so either of them could be used for this purpose. If the 486K resistor in your diagram is R89, then your hookup looks normal.

Do you see anything at all connected to other pins on the 1X2 socket? Pins 3 and 7 are not used for anything, so they would be free to use as tie points for unrelated stuff, although I don't recall seeing any such things on a HV rectifier socket before.

Phil Nelson

http://antiqueradio.org/art/temp/Majestic1600HV.jpg

Pin 5 is empty in the socket, no connection there. On my picture I should have drawn the connection from pin 6 to pin 8 AROUND the flyback instead of next to it. It wraps around the flyback but it is not connected to it. All of those connections read infinite impedance to ground by my meter.
R95 is actually reading around 3.6 ohms which is right at 20%. Possibly this should be changed but could that little fluctuation in tolerance possibly be the entire cause of the problem?

Shorted to ground? It doesn't read shorted. I don't have a capacitor tester so I can only test if it's shorted.
You're using the highest ohms scale, and it's reading open circuit, right?
R95 is actually reading around 3.6 ohms which is right at 20%. Possibly this should be changed but could that little fluctuation in tolerance possibly be the entire cause of the problem?
No, not a chance.

You're using the highest ohms scale, and it's reading open circuit, right? Now how about from the 1X2 filament loop to ground?

All connections on the 1X2 socket read open to ground.

It wraps around the flyback but it is not connected to it.
Yes, the filament winding just wraps around the flyback.

Phil Nelson

Yes, the filament winding just wraps around the flyback.

Phil Nelson

Is there a reason for this? Or is it just something that's done?

Is there a reason for this? Or is it just something that's done?

That's how the power for the filament is pulled from the flyback. One turn is all it takes.

If the door knob cap and other parts in the high voltage circuit check good, I would look to see if the horz osc is way off frequency. It is possible that the fly back is sending too much voltage into the 1x2 tube and over dosing the tube.
Do you have a hi voltage probe? If you do, Check and see it the hv is way to high. Another check may be to see if the crt is your problem. Put the anode connector in a plastic or glass cup, Fire up the set and see if the problem goes away. Btw, Nice set you have there. You have done a good job on it.
Ed

Btw, Nice set you have there. You have done a good job on it.
Ed

You have no idea how good that is to hear.

If the door knob cap and other parts in the high voltage circuit check good, I would look to see if the horz osc is way off frequency. It is possible that the fly back is sending too much voltage into the 1x2 tube and over dosing the tube.

I've seen cases of the horiz. being miles off-frequency, but never saw (or heard of) it causing the fly to put out 'too much' juice. The HV is not the product of the sweep frequency but of the fast "fly-back" spike of the sawtooth.

Just wondering if maybe the second 1X2 could be bad. This'd be one case where it would be handy to have a SS stick rectifier to sub in there. oc

I've seen cases of the horiz. being miles off-frequency, but never saw (or heard of) it causing the fly to put out 'too much' juice. The HV is not the product of the sweep frequency but of the fast "fly-back" spike of the sawtooth.

Just wondering if maybe the second 1X2 could be bad. This'd be one case where it would be handy to have a SS stick rectifier to sub in there. oc

Where might one procure such a thing?
The new 1X2B that I have was brand new in the box for whatever that's worth. I'll see if some one else I know has a known good 1X2 to test with.

Have you checked the 1X2's filament for continuity? Here's the data page with basing diagram..
http://www.nj7p.org/Tube4.php?tube=1x2

Have you checked the 1X2's filament for continuity? Here's the data page with basing diagram..
http://www.nj7p.org/Tube4.php?tube=1x2

Filament has continuity.
After much thought I decided that this latest problem happened after I changed 10 tubes and 4 caps. I thought I would take a closer look at the items I replaced before the problem. Following the schematic to each cap I replaced led me to C62. C62 is connected to pin 3 on V17 and ground according to the schematic (as far as I can tell). Can some one confirm this? On the set it is connected to pin 3 and pin 7 on V17. I know I replaced lead for lead of the old cap and can still see a small amount of the lead of the old cap to confirm this. The old cap was one of the black beauties I mentioned that I missed before. I tested pin 7 and it is not connected to ground. Maybe I'm following some one else's botched repair? Or maybe I'm just misreading the schematic?
One other question. The schematic shows pin 7 and pin 8 of V17 connected to "Y" and "Z." There are some other connections on the schematic labeled as such. What does Y and Z refer to?

"X" and "Y" are probably tube heater windings on the power transformer, look around the power supply on your schematic, and you will probably find what they are connected to.

Tom C.

Yes, there is a separate filament supply (Y and Z) for the damper tube and kinescope (the other tube filaments are supplied by connecting to the X supply and ground):

http://antiqueradio.org/art/temp/Majestic1600PS.jpg

I think I read somewhere that a damper is given a separate filament supply to reduce the risk of heater-to-cathode shorts, when its cathode is at hundreds of volts above ground.

The schematic seems to show that C62 connects to ground in some models and to the +255vdc source in other models:

http://antiqueradio.org/art/temp/Majestic1600Damper.jpg

A note elsewhere says, "Dotted in parts are not used in all models. When dotted in parts are used, points marked X are broken." In other words, that leg of C62 would connect either to +255vdc or to ground, depending on model.

Referring back to the first picture, the +255vdc source is separate, not the same as the Y filament source that connects to pin 7 of the damper. So, if I follow this correctly, connecting C62 between pins 3 and 7 is not right for either model.

Here is a bigger chunk of the schematic showing other dotted-in stuff:

http://antiqueradio.org/art/temp/Majestic1600.jpg

There you see that C61 is like C62, connecting either to +255vdc or to ground, depending on model. Parts R95, R97, and C71 are also dotted. Perhaps if you check how all those components are connected in your set (and whether R97 and C71 are even present), that will give a clue how to connect C62.

Phil Nelson

Thanx for chiming in there, Phil. I had formulated a post saying essentially the same thing, but you beat me to it.:D

One thing's still puzzling- he says C62 was connected to pin 7 of the 6W4. That would put it from cathode (pin 3) to heater (pin 7), which would make no sense...

unless....

...the floating heater is clamped to the 255V supply via pin 7.

Otherwise, C62 has gotta go either to ground or to the 255V supply depending on model.

oc

I keep checking this topic to see- "is this the post to say he got it working?"

I've been on the edge of my seat... Great work so far, can't wait to see a picture on it :)

I keep checking this topic to see- "is this the post to say he got it working?"

I've been on the edge of my seat... Great work so far, can't wait to see a picture on it :)

's what I love about AK - the restoration projects here aren't just one person's work - everyone takes part and can't wait to hear of or see the end result when it works.

Occupational hazard too - this feeling is contagious...

Fingers crossed- we've got the champagne sitting ready :D

I've seen cases of the horiz. being miles off-frequency, but never saw (or heard of) it causing the fly to put out 'too much' juice. The HV is not the product of the sweep frequency but of the fast "fly-back" spike of the sawtooth.

Just wondering if maybe the second 1X2 could be bad. This'd be one case where it would be handy to have a SS stick rectifier to sub in there. oc

Dug out this Zenith { Chassis14Z33 } from the B@W room and connected the HV probe to the to the anode of the CRT. I picked this set because it has a vary stable tube horizontal oscillator/output circuit and a coil for the horizontal hold control. Turned on the set and let it warm up, With a normal picture the HV reads 19kv on the probe. Then I turned the horizontal coil one and a half turns counter clockwise. The picture went out of sync and the HV went up to 22 KV. What else was interesting is when I turned the coil one more rotation counter clockwise the HV went back down to 19KV and the picture was a horizontal mess. This proves that there is a direct connection between the horizontal oscillator and the high voltage. I guess I just do not know how to explain the problem properly. All I know is I have seen this type of problem before in the 1950"s set's and they are hard to track down. Also the horizontal circuits are not as stable in a 50's set as the horizontal circuit in a 1969 zenith.
I am not a big fan on installing solid state diodes in place of a diode tube. I tried it once with a ctc 15 chassis damper tube and it increased the horizontal output tube current. Plus it looks funny on the chassis.
Ed

That's an interesting observation, Ed. To tell the truth, I had never tested the correlation between sweep frequency and HV level. But it stands to reason that changing the sweep freq also changes the duration of the retrace/'fly-back' spike from which the HV is derived via resonance (or near resonance) with the secondary winding (the 'tire').
But as you demonstrated, there's only a moderate peak as you tune through it, not a continuous ascent.

Re. the SS stick, I was referring to the HV rectifier type, not a damper. Replaced enough of those in CTC-22s. Gaak.:eek: oc

Quick question to all of you. Are there any tubes that if removed from the set would do damage to the set if it's fired up without them?

...Are there any tubes that if removed from the set would do damage to the set if it's fired up without them?
Oh yes indeed. The horiz. oscillator. If for any reason the H.output tube loses drive, it loses the negative bias voltage* on the control grid (G1). The plate current goes through the roof and if there were no fuse the output tube could be destroyed in short order, possibly cooking the fly also. That's why there's usually a fuse there for protection.

Removing either of the vertical tubes would kill vertical sweep, which could burn a line across the screen if allowed to run that way. oc

*This voltage is developed by the G1-cathode diode action rectifying the drive signal.

The reason I asked is I thought I would check back through the tubes to make sure I didn't mix some of them up when I reinstalled all of them. I noticed two things. V10 is a 6AT6 on the schematic and I have a 6AV6 installed. I mentioned this before and was told it was ok but thought I would mention it again. V15 (the horizontal output) on the schematic is a 6AV5GT and I have a 6AV6GA installed. Are these interchangeable or is this no good? Also I replaced C40 with a .022mf cap because that is what the capacitor list called for, but the alternate schematic (which is actually what I have) calls for a .002. Is .022 too much for a replacement? If the horizontal tube isn't the whole problem in a nutshell (I'm sure it's not, that would be too easy), I think I'll look back through the set and make sure I didn't replace other caps with the wrong capacitance because of the parts list being different from my set.

The 6AV6 and 6AT6 have identical specifications and pinouts.

...schematic is a 6AV5GT and I have a 6AV6GA installed.

A quick google shows me that the filament pins for these two tubes are not the same, so immediately I would say they are NOT compatible. It also looks as if one is a 7-pin tube and the other an 8-pin tube.

Can you trace the 6.3v filament line to the pins on the socket? The place they come out should indicate which tube is correct.

6AV6 specs (http://tdsl.duncanamps.com/show.php?des=6AV6) - Filament pins 3 & 4
6AV5 pinout (http://oldradio.qrz.ru/tubes/foreign/01/6AV5.gif) - Filament pins 2 & 7

Sorry I made a mistake. I have a 6AV5GA installed not a 6AV6GA. My mistake VintagePC.

Sorry I made a mistake. I have a 6AV5GA installed not a 6AV6GA. My mistake VintagePC.

Ah, that makes a little more sense :) No worries.

Per RETMA designation (http://en.wikipedia.org/wiki/RETMA_tube_designation), they should be compatible - the original GT suffix just means glass tube, whereas the GA suffix suggests glass tube (G) and a revised version that's backward compatible (A).

What's funny is I read the Wiki pages for RETMA and RMA tube designation just for kicks once... now I keep finding myself back on them :)

OK, maybe I found it! I was looking over C61 and C62 again to make sure they are installed correctly. C62 is indeed connected to +255v so all ok there. However, I am 99.9% sure C61 is MISSING! I will be especially sure this is the case if some one can speculate that a missing C61 would cause my glowing V18 problem.

This is also further reinforced by the fact that I had a cap with same value as C61 left over when I did the original recapping.

That could well do it!

Considering C61 is part of what comes out of the 1x2 cap -> through a transformer.

That means without C61, your flyback won't operate properly.

I'd connect it in the same way as C62 - using the optional 255V connection.

That could well do it!

Considering C61 is part of what comes out of the 1x2 cap -> through a transformer.

That means without C61, your flyback won't operate properly.

I'd connect it in the same way as C62 - using the optional 255V connection.

I would say the optional 255V connection is the way to go. Every thing else I've seen on the schematics have been in the optional dotted line configuration. I'll give the set a second and third look over to make triple sure that it is not in place and if it's not we'll see how it goes.

That could well do it!

Considering C61 is part of what comes out of the 1x2 cap -> through a transformer.

That means without C61, your flyback won't operate properly.

I'd connect it in the same way as C62 - using the optional 255V connection.
If C61 was indeed missing, it'll be interesting to see what happens when he replaces it, since it is the bypass/'filter' for the bootstrapped (B boost) voltage. Since the vertical oscillator is supplied from B boost, the absence of C61 was probably introducing some wonkiness into the vertical waveform too.

What still puzzles me is- he was drawing a healthy 'air arc' off the plate connector of the 1X2. Assuming the replacement 1X2 is good, there should definitely be adequate HV coming out of it.. assuming there is no short to ground. One remaining possibility is that the second 1X2 is gassy. So one question- is the 1X2 getting hot after a few minutes of running? If it's hot, like too hot to touch, it would indicate the tube's gassy (even though it might still test good on a tester).

One remaining possibility is that the second 1X2 is gassy. So one question- is the 1X2 getting hot after a few minutes of running? If it's hot, like too hot to touch, it would indicate the tube's gassy (even though it might still test good on a tester).

I've only had the set on for seconds after noticing the problem so I don't know if the 1X2 is hot to the touch. I could test this theory if you think it's ok to leave the set powered up for that long.

It should be all right, (and I'm sure you know this) but don't run it unattended. (and replace C61 before you do fire it up!)

I like to run things through a power bar so I have a kill switch on hand that's not near/on the set, just in case. Then, keep watching and listening for any funny business and kill it if anything else starts acting weird. Keep a good eye on the flyback and kill the power if it starts to drip wax!

I should add that gassy tubes usually have a blue-violet flickering glow to them, which is in the _space_ inside the tube... What it looks like you have (and you can confirm this, since cameras don't usually do fluorescent colours justice) is a pure, deep blue coming from the inner layer of glass itself- that's entirely the fluorescent emission of the glass from being bombarded with high-energy electrons.

There's a couple of videos on YouTube (heh) if you search "gassy tubes" that will help you distinguish between the two.

I've only had the set on for seconds after noticing the problem so I don't know if the 1X2 is hot to the touch. I could test this theory if you think it's ok to leave the set powered up for that long.
Umm.. considering the rarity and irreplacibility of that flyback, and since you haven't already run it for more than a few seconds in the fault state, please hold off on this test.
Rather (after replacing C61), do the 'air arc' test again. It will confirm whether the fly's putting out without loading it down.

Now, if the fly's putting out, install the 1X2 with the plate cap connected, and remove the doorknob. This will avoid loading the flyback (in case the tube is gassy). If the tube is good, the HV should come up and light the CRT. If the 1X2 is gassy, it may fry the 470K resistor (R89) in series with the HV lead. R89 is thus "sacrificial" and takes the load otherwise borne by the flyback with a gassy 1X2. Much easier to replace a resistor than the flyback.

Yah, some tubes can glow pure blue and work fine. I have observed this in a couple of sets.

Purple, not so good. The photo shows a 5U4G rectifier in my RCA T-100 just before it failed completely. Definitely purple rather than blue. There was nothing wrong with the TV, that old tube just gave up the ghost.

Phil Nelson

http://antiqueradio.org/art/temp/Fried5U4G.jpg

I guess .1% wins this time. I found C61. It is a .05 instead of a .035 though. It was one of the black beauties and didn't have it's rating on it. It had the same marking bands as two other black beauties that were .05 though.

A few youtube searches on gassy tubes and I think this is what I have. The last two posts came in after I did the test so didn't have a chance to read the "don't do that" warning. The set was still only on for less than a minute.
http://www.flickr.com/photos/23097242@N03/5873904324/
This will help make it a little easier to see what the tube is doing. The video is of the new tube. The old tube does close to the same thing, just not nearly as much blue glow. I suppose #3 could be the charm.

Are you still hearing the hissing or spitting sound? A length of plastic tube held to your ear can help you pinpoint its location.

Phil Nelson

Are you still hearing the hissing or spitting sound? A length of plastic tube held to your ear can help you pinpoint its location.

Phil Nelson

I am hearing a sparking noise, but I think it's coming from the 1X2 itself. You can see in the video that it is sparking on the inside. This is also what the old tube did.

Killer suggestion on the length of tube though. I will definitely remember that for the future.

If the doorknob isn't causing the arcing, it could be the socket itself. Have you checked it yet? Carbon tracking on HV parts can cause shorts from seemingly nowhere, so make sure you inspect the rectifier tube socket and replace it if you're in any doubt.

If the doorknob isn't causing the arcing, it could be the socket itself. Have you checked it yet? Carbon tracking on HV parts can cause shorts from seemingly nowhere, so make sure you inspect the rectifier tube socket and replace it if you're in any doubt.

Interesting thought. I'll inspect.

The photo shows a 5U4G rectifier in my RCA T-100 just before it failed completely. Definitely purple rather than blue.

Damn, that thing is TOASTY!


http://www.youtube.com/watch?v=x7KK7bXJV2c

Another check may be to see if the crt is your problem. Put the anode connector in a plastic or glass cup, Fire up the set and see if the problem goes away.
Ed

Tried this and it's not the problem.

Umm.. considering the rarity and irreplacibility of that flyback, and since you haven't already run it for more than a few seconds in the fault state, please hold off on this test.
Rather (after replacing C61), do the 'air arc' test again. It will confirm whether the fly's putting out without loading it down.

Now, if the fly's putting out, install the 1X2 with the plate cap connected, and remove the doorknob. This will avoid loading the flyback (in case the tube is gassy). If the tube is good, the HV should come up and light the CRT. If the 1X2 is gassy, it may fry the 470K resistor (R89) in series with the HV lead. R89 is thus "sacrificial" and takes the load otherwise borne by the flyback with a gassy 1X2. Much easier to replace a resistor than the flyback.

Ok tests ran, here are the results. Fly is air arcing away. Door knob removed and HV going right to the picture tube. I want to rewind a bit to before. Miniman82 first suggested removing the doorknob cap and firing the set up to see if that solved the problem. The doorknob cap is secured to the base of the rectifier through a screw in the base to the top of the cap. On my first test I removed the screw. On this test I removed the screw and MADE SURE that the base was not in contact with the cap at all. Different result. The tube did not glow or crackle at all this time. Unfortunately a new arc has developed. It is between the flyback and the filament winding for the rectifier. I've indicated where it is with the white arrows below. It is not constant, and only happened 8 or so times total with all the tests I have done tonight. It seems that Miniman82 might have put his money in the right place and the doorknob is toast. It is not shorted to ground but it could be toast. A new doorknob might be the answer. I don't know what to do about the sparking flyback though.

http://farm4.static.flickr.com/3016/5873767145_a8bbe8cc94.jpg

Most people here will coat the flyback with a "sensor-safe" silicone product (regular silicone produces ammonia or acetic acid as it cures, which corrodes copper). That will likely kill the arcing. A few wraps of PVC electrical tape might work in a pinch for testing until you can get the right stuff.

At this point, I'd recomment replacing the filament winding for the rectifier and the doorknob cap. I often find filament windings have degraded insulation, and that's never a good thing around HV.

Got a good supplier for a 500pf 20,000v door knob capacitor?

Digi-key has a few... for example:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-3890-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-2235-ND


... but they won't be cheap :S

Well sunnava gun, so it was the doorknob all along, and now the filament winding is popping through. Some kind soul oughta send him a hunk of HV wire to replace that with, along with a doorknob.

So as I sit here and ponder I can't help but think that the door knob cap ISN'T shorted to ground. If that cap was shorted to ground it would certainly account for our problem, but could just a leaky cap cause our problem? If not could it be the ground side of the cap some how isn't grounded? Or some other problem other than the cap itself being bad. I just know that some times in my work when I think I've found the answer from trouble shooting I just end up "fixing" things that aren't broken and still not finding the real problem.

OK, did the CRT light up with a raster after you removed the doorknob? If so, it would pretty well prove the doorknob was at fault. Probably arcing internally since it measured open circuit on your ohms test.

Earlier you mentioned a "new arc" that's developed. I (probably erroneously) interpreted it to mean there's a hole in the insulation of the filament winding that's allowing a DC arc. That would be evinced by a loud, sharp snapping sound. If instead the "arc" is a bluish, lightly hissing corona discharge from the 'tire' to the filament loop, you may be able to insulate it with some silicone. Is it possible to move the filament loop further down on the frame, away from the 'tire'?

I have a new theory. The old 1X2 tube was fine. The new 1X2 is bad. The "new" arc I described from the "tire" to the filament loop was always there and I never noticed it. Every time there was a discharge from the tire to the filament loop it was echoed inside the 1X2, making me think the tube itself was bad. I've removed the flyback and there is no insulation missing from the filament loop at all. The "tire" has an area where it looks slightly melty, but only slightly. I'm going to get it nice and insulated with the afore mentioned sensor safe silicone, attempt to get the filament loop as far away from it as possible and reinstall with the old 1X2.

One thing that struck me as odd was there was already three or four pieces of electrical tape squares stuck between the "tire" and the filament loop. Looks like the problem could have been there before when the set was in use.
This theory makes absolutely the most sense to me so far.

OK, did the CRT light up with a raster after you removed the doorknob? If so, it would pretty well prove the doorknob was at fault. Probably arcing internally since it measured open circuit on your ohms test.

The CRT lit up with a raster before I removed the doorknob, and after as well.

A capacitor can leak internally when voltage is applied, yet test as "not shorted" using an ohmmeter. The voltage applied by a general-purpose multimeter is negligible compared to the actual working voltage. That's why they made dedicated capacitor testers. Mine can check a cap at any voltage up to 500v. I haven't heard of any cap checkers that can test in the KV range, however. For a doorknob like this, the test is substituting a known-good cap and observing what happens. Which was no problem in Ye Olden Dayes when the repairman would just fish one out of a bin on the shelf and pop it in.

If it looks like you need a new doorknob, Surplus Sales of Nebraska has one at 500pf/20KV for a low, low price of $35:

http://www.surplussales.com/Capacitors/Trans_Coup_Caps/cap_trans.html

Click on the "Available in these styles" link to see whether that type would replace what you have.

It's not a cheap part, so I'd proceed with whatever testing is needed to isolate that as your trouble source.

TVs can have more than problem at a time, of course. If you also want to replace the 1X2 filament loop, I believe that needs to have HV-rated insulation.

The photo shows some sensor-safe RTV that I used on a Philco flyback.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

http://antiqueradio.org/art/PhilcoF4626MFlybackWaxRemoval.jpg

I have a new theory. The old 1X2 tube was fine. The new 1X2 is bad. The "new" arc I described from the "tire" to the filament loop was always there and I never noticed it. Every time there was a discharge from the tire to the filament loop it was echoed inside the 1X2, making me think the tube itself was bad. I've removed the flyback and there is no insulation missing from the filament loop at all. The "tire" has an area where it looks slightly melty, but only slightly. I'm going to get it nice and insulated with the afore mentioned sensor safe silicone, attempt to get the filament loop as far away from it as possible and reinstall with the old 1X2.

One thing that struck me as odd was there was already three or four pieces of electrical tape squares stuck between the "tire" and the filament loop. Looks like the problem could have been there before when the set was in use.
This theory makes absolutely the most sense to me so far.

FAIL!
No more discharge from the fly to the filament winding but problem is not solved. Every time I get over 95v I get sparks on the inside of the old 1X2, and sparks plus a blue glow on the new 1X2.
Time for a new $35 capacitor.

FAIL!
No more discharge from the fly to the filament winding but problem is not solved. Every time I get over 95v I get sparks on the inside of the old 1X2, and sparks plus a blue glow on the new 1X2.
This is with the doorknob removed, right? What's happening to R89, the 470K resistor? Is it getting hot, or remaining cold? If R89 remains cold, there may be a leakage path from the 1X2 socket itself to ground that's dragging down the HV. If R89 is getting hot, it may be that the 1X2 (in this case either one) is gassy and passing unrectified pulse that's hammering the resistor.
Time for a new $35 capacitor.
A new cap isn't going to help until you get the current problem sorted out. All this cap does is smooth the rectified pulse coming out of the 1X2.

One other thing- when you re-installed the flyback, where you soldered the filament loop back to the 1X2 socket, are there any whiskers or sharp points to the joints? In soldering any HV connections it's very important to build a nice 'ball' of solder on each joint to eliminate any points.

He previously said that with the doorknob removed there was no arcing within the 1X2 or glow. So, the doorknob could be breaking down internally causing the arcing within the 1X2.

The arcing from the filament loop is another issue.

John

This is with the doorknob removed, right? What's happening to R89, the 470K resistor? Is it getting hot, or remaining cold? If R89 remains cold, there may be a leakage path from the 1X2 socket itself to ground that's dragging down the HV. If R89 is getting hot, it may be that the 1X2 (in this case either one) is gassy and passing unrectified pulse that's hammering the resistor.

A new cap isn't going to help until you get the current problem sorted out. All this cap does is smooth the rectified pulse coming out of the 1X2.

One other thing- when you re-installed the flyback, where you soldered the filament loop back to the 1X2 socket, are there any whiskers or sharp points to the joints? In soldering any HV connections it's very important to build a nice 'ball' of solder on each joint to eliminate any points.

What's happening to R89, the 470K resistor? Is it getting hot, or remaining cold? If R89 remains cold, there may be a leakage path from the 1X2 socket itself to ground that's dragging down the HV. If R89 is getting hot, it may be that the 1X2 (in this case either one) is gassy and passing unrectified pulse that's hammering the resistor.

Stupid question, but I'm not afraid to look stupid to get it right. "Hot" and "cold" aren't euphemisms right? If they are not euphemisms then would a simple finger test be recommended for a thermometer (after discharging the HV of course)? How "hot" is hot and how "cold" can it run? Also how long should the set heat up before testing temp?

This is with the doorknob removed, right?
My results of:
Over 95V I get sparking on the inside of the old 1X2, and sparking plus blue glow on the new 1X2 were with the doorknob installed.
Previously when I thought I had removed the doorknob from the equation I had infact not. Tonight I removed, completely, the doorknob from the set. The results with the doorknob removed:
Blue glow on the new 1X2 (although not as strong as when the capacitor is installed). No glow on the old 1X2. After leaving the voltage around 100V for 70 seconds or so both tubes made a pffffssst noise. I fired the set down immediately after hearing this.

The only things that are connected post 1X2 at this point are the filament loop, two resistors, and the anode connection on the picture tube. I've tested the set without the anode connection to the picture tube and it failed. Both resistors measure within 20%. The filament loop is solid and double insulated where is loops through the flyback. While the doorknob was removed I took the time to make sure all solder points on the base of the 1X2 are smooth. I'm thinking that the only two things that remain are the 1X2 itself, and the flyback output to the 1X2. I'm going to try another 1X2. As far as the flyback output is concerned, I will obtain a high voltage probe to measure the output. Does any one know what the voltage should read out of the flyback? Hopefully this will pinpoint the exact problem.

In my unscientific mind, "hot" would be too hot to touch.

Regarding flyback output, the data sheet for that CRT says the typical anode voltage is 12KV. Recommended max = 14KV, min = 10KV.

http://scottbecker.net/tube/sheets/093/1/16GP4.pdf

That would be measuring at the end of the HV anode lead. Since the CRT lit up before, I'm guessing you have several KV, at least.

I wonder if the 1X2 socket could be faulty? Have you carefully inspected it using a strong light, and looking for any cracks, black carbon trails, etc.? If you leave the doorknob disconnected and use a listening tube, perhaps you could tell whether the Pfffft sound comes from the socket.

Phil Nelson

Maybe I should just replace the tube socket was well. I'll do all of these things one at a time to pinpoint the exact problem.

All learning experiences for the next one :).

Stupid question, but I'm not afraid to look stupid to get it right. "Hot" and "cold" aren't euphemisms right? If they are not euphemisms then would a simple finger test be recommended for a thermometer (after discharging the HV of course)? How "hot" is hot and how "cold" can it run? Also how long should the set heat up before testing temp?
Well, assuming it's a half-watt, "hot" would mean blistering and probably smoking after a minute or two. Since it's holding value within tolerance and showing no sign of overheating it would be 'cold'.
As far as the flyback output is concerned, I will obtain a high voltage probe to measure the output. Does any one know what the voltage should read out of the flyback? Hopefully this will pinpoint the exact problem.
A HV probe is DC only and will not measure the direct output of the fly, which is pulsed RF. The probe will measure anything 'downstream' of the 1X2 however, which is DC. Since you've already gotten a hefty 'air arc' off the fly and have seen a raster of full width and adequate brightness, this indicates the fly is performing up to par.
Tonight I removed, completely, the doorknob from the set. The results with the doorknob removed:
Blue glow on the new 1X2 (although not as strong as when the capacitor is installed). No glow on the old 1X2. After leaving the voltage around 100V for 70 seconds or so both tubes made a pffffssst noise. I fired the set down immediately after hearing this.
This suggests to me a leakage path from the tube socket itself to ground that's killing the HV and thus leaving resistor R89 cold and unmolested. Is there any way you can temporarily remove the mountings of the socket so it 'floats' free of any connection to ground? This would prove whether or not a leakage path through the mounting(s) exists. The "pffssst" noise certainly sounds like such a leakage condition.
The only things that are connected post 1X2 at this point are the filament loop, two resistors, and the anode connection on the picture tube. I've tested the set without the anode connection to the picture tube and it failed. Both resistors measure within 20%. The filament loop is solid and double insulated where is loops through the flyback. While the doorknob was removed I took the time to make sure all solder points on the base of the 1X2 are smooth. I'm thinking that the only two things that remain are the 1X2 itself, and the flyback output to the 1X2. I'm going to try another 1X2.
I would definitely try 'floating' the socket as the next troubleshooting step if it's doable.

Woop. Hi Phil. Looks like you were zeroin' in on the same thing.:naughty:

Well, there are so few things connected to the 1X2. At this stage, I'm scratching my head thinking, What is left besides the socket??

Phil Nelson

VTS1134. Try turning down the horizontal drive control and see if the arcing goes away or calms down. If it is a tuning cap that would be counter clockwise but try turning it in both directions. The sides of the screen should cave in and the picture will loose brightness. I thought I saw a drive control in the schematic. Also do you have a signal going into the set? Is the picture normal and has vertical and horizontal sync? If you are going to keep working on vintage TV a HV probe is a good idea. At some point you may want to restore a color set and a probe is a must.:thmbsp:

Well, there are so few things connected to the 1X2. At this stage, I'm scratching my head thinking, What is left besides the socket??
Nothing except whatever the socket mounts to that could sustain a leakage path to ground. Hence the suggestion that he remove the mounting(s) if possible and 'float' the socket for a test.

If you also want to replace the 1X2 filament loop, I believe that needs to have HV-rated insulation.

Is this a locally available material? I tried the local electrical supply house that we have an account with but they don't have anything like this. I'm not sure what to call this and therefore google it and get online results. Any thoughts?

I guess I would call it high voltage wire. Surplus Sales of Nebraska has 40KV-rated wire for $2.90 per foot.

http://www.surplussales.com/Wire-Cable/HVWire-1.html

I don't know what's available in your locale. Electronics supply stores are practically nonexistent around here, so I buy everything online.

Phil Nelson

Thanks Phil. I'm going to try a couple more places in my area before resorting to ordering 25ft of the stuff.
I found out the pfffssst sound was corona discharge from the filament loop so I'm going to start with that.

Just rob it from a newer set. I get mine from BPC stuff, just cut the anode lead off the flyback and discard the HV cup.

Just rob it from a newer set. I get mine from BPC stuff, just cut the anode lead off the flyback and discard the HV cup.

Bingo. Never thought of that, we throw tube TVs away almost daily!

Update.
I've replaced the filament loop wire with 50kv rated wire. I've also got a third 1X2. Those haven't solved the problem. I also now have a high voltage probe and am getting some interesting readings. The 16GP4 has a maximum anode voltage rating of 14kv. I can't get the input voltage on the set over 95v before I am above 14kv on the anode. Anode voltages above 14kv is also when I start to have problems with the 1X2 sparking and glowing.
I've also adjusted the horizontal drive as per roundscreen's suggestion. Turning the drive up increases the anode voltage and subsequently makes the 1X2 spark and glow when voltage reaches over 14kv. As long as I keep the anode voltage below 14k I can run the set as long as I want with no 1X2 problems.
Any thoughts on why my anode voltages are so high with the set on 3/4 power? Sounds like this might be the whole problem, but what could be the cause?

Yes, I definitely agree that you have found the problem with the rectifier. Regarding the cause, I would test other voltages in the power supply and horizontal circuits with the AC input set at 90 or 95 volts.

The maximum peak inverse voltage on a 1X2 is 15kv so I think you found the rectifier problem too.

Are you measuring the HV with the 16GP4 installed ? If not, it might be to high because there's no load.

The maximum peak inverse voltage on a 1X2 is 15kv so I think you found the rectifier problem too.

Are you measuring the HV with the 16GP4 installed ? If not, it might be to high because there's no load.

I'm measuring with the 16GB4 installed. Thanks for asking/pointing out obvious things, helps folks like me greatly.

After some measuring I found that my "Y" and "Z" voltages are too high as measured directly on pin 5 and 7 of V19 (the lv rectifier). Is it possible to remove the leads of the transformer from V19, give the set voltage, and measure the output directly without harm? If it is and it still measures too high is the transformer at fault? There is not much in front of the transformer but a couple of filter caps.

Vts1334,
It seems very doubtful that three 1X2s are all gonna be displaying an acring/sparking problem such as you describe, even with the driving voltage being a little over spec. The tubes should have enough 'headroom' to be able to handle it without a problem.

As was suggested back in posts 210 and 214, what you describe sounds more like something under the 1X2, not the tube itself, is doing the arcing/sparking.. like maybe a leakage path from the socket to ground.

As a test of this theory, if it's possible to temporarily 'float' the socket by removing whatever it's mounted to, that would eliminate a leakage path as the problem.
oc

Vts1334,
As was suggested back in posts 210 and 214, what you describe sounds more like something under the 1X2, not the tube itself, is doing the arcing/sparking.. like maybe a leakage path from the socket to ground.

As a test of this theory, if it's possible to temporarily 'float' the socket by removing whatever it's mounted to, that would eliminate a leakage path as the problem.
oc

I did this. The socket was only connected to the tube and the lead to the picture tube. I still had the same problem. The sparking is definitely coming from inside the tube itself. The problem I had below/around the tube was corona discharge from various locations, the "tire," the filament loop, the connection to the wire lead to the picture tube, etc...
Wouldn't it make sense that if those components are driven past their voltage limits that they would begin to show corona discharge?
It seems very doubtful that three 1X2s are all gonna be displaying an acring/sparking problem such as you describe, even with the driving voltage being a little over spec. The tubes should have enough 'headroom' to be able to handle it without a problem.

How much head room do you think they have? With the input voltage at 90v y and z are already at 270vdc. At input voltage of 95v and the anode voltage reading 14kv (the limit according to the 16gp4 spec) there is no problem in the high voltage area. Above 95v input, when y and z get up over 310v then SPARK! I haven't measured anode voltage when the 1X2 is at it's fail point but I suspect it's a good deal over 14kv.

I did this. The socket was only connected to the tube and the lead to the picture tube. I still had the same problem.
Ok, my bad. I didn't realize you'd already done this.
The sparking is definitely coming from inside the tube itself. The problem I had below/around the tube was corona discharge from various locations, the "tire," the filament loop, the connection to the wire lead to the picture tube, etc...
Wouldn't it make sense that if those components are driven past their voltage limits that they would begin to show corona discharge?
Yes, now that you've done the 'float' test.
With the input voltage at 90v y and z are already at 270vdc. At input voltage of 95v and the anode voltage reading 14kv (the limit according to the 16gp4 spec) there is no problem in the high voltage area. Above 95v input, when y and z get up over 310v then SPARK!
I don't have access to the LV supply section of the schematic. But the most relevant voltage is where the flyback system itself is supplied. That would be at lug# 6 of the flyback. The print calls for 210V. If that voltage is signifigantly over spec, it could sure as heck be overdriving the whole flyback system.

The schematic shows 255V at other locations in the chassis. Is that voltage over spec too? If it is, it would suggest the LV power supply is putting out too much juice. Is there any evidence of the power transformer having been replaced?

Or if the 255V source is not over spec, could there be a miswire somewhere that's putting 255V onto the 210V line?:sadwave:

Maybe Phil could post the print showing the LV section.:D:deal:

One thing's for sure- we all gotta admire the heck outa your tenacity in rassling this critter. For a total Noob, it's truly been a baptizm of fire. When you get it whipped, you can rightly call yourself The Dragonslayer.

If the focus coil were open or disconnected maybe the +255 would be too high.

Anyhow, here's the power supply section.

John

Anyhow, here's the power supply section.

John
Aha. Thanks John. One piccy's worth a thousand words. I think i forgot that Phil did post that earlier. Geezerly brain fade.

So vts1134, what is the actual voltage at the input side of the choke (L1)? What is the voltage on the downstream side of L1, where the focus coil connects? Is it signifigantly over the specified 255V?

What is the voltage at the downstream side of the focus coil, where it connects with filter C2D? Is it signifigantly above the specified 210V?


Forget 'Y' and 'Z'. That's just the 'floating' heater supply for the damper and not relevant to the problem at hand.

Just a little FWIW regarding the damper's floating heater winding. Since there is a high level pulse of a few thousand volts on the cathode, there's potential for heater-cathode arcing (a very common problem with damper tubes). By allowing the heater to float (rather than being clamped to ground like the rest of the heaters), the effective pulse level between heater/cathode is reduced, thereby reducing arcing potential.

Most sets don't use a dedicated supply to float the damper's heater. In fact this feature is found only in a few old high quality sets.

One thing's for sure- we all gotta admire the heck outa your tenacity in rassling this critter. For a total Noob, it's truly been a baptizm of fire. When you get it whipped, you can rightly call yourself The Dragonslayer.

Ha, just wait. This is only the latest problem, I haven't told you that I still don't have a picture yet. It might be a while until this is over. I know I've said it before but I can't thank you all enough for teaching me what I know refer to as my crack addiction. I can't wait until I can show you a picture on this bad boy, take a 5-7 minute break to admire it, and start the next one :D.

If the focus coil were open or disconnected maybe the +255 would be too high.
John

The focus coil is right on spec.

Aha. Thanks John. One piccy's worth a thousand words. I think i forgot that Phil did post that earlier. Geezerly brain fade.

So vts1134, what is the actual voltage at the input side of the choke (L1)? What is the voltage on the downstream side of L1, where the focus coil connects? Is it signifigantly over the specified 255V?

What is the voltage at the downstream side of the focus coil, where it connects with filter C2D? Is it signifigantly above the specified 210V?


Forget 'Y' and 'Z'. That's just the 'floating' heater supply for the damper and not relevant to the problem at hand.

I've found that all of the above locations are above spec voltage, but not so much as to be a problem.
I'm going to continue to look for out of spec voltages. In the meantime my question du jour has to do with L18, the horizontal size control. The schematic calls for an impedance of 35 ohms. It doesn't give it a value range though. Would 35 ohms be on the high side, or low side? The reason I ask is that my horizontal size control is at 3 ohms and spins, but does not adjust in impedance. Obviously broken, but could this cause an over voltage situation on the fly? The schematic gives it two Majestic part numbers, they are B-1.533-1 and B-1.532-1. Does any know what these part numbers would correlate to on a replacement part?

vts1134,

While it is possible that some component in the set has failed, you seem to have followed a logical step-by-step trouble shooting path and you have not located the problem. Let's do a little thinking out side of the box.

1) Is the variac that you are using an old fashion one with an autoformer and a mechanical slider in it?

1a) If yes, have you checked the output voltage with a different volt meter? It is possible that the built-in volt meter is off.

1aa) If yes and the meter is not correctly reading, check the variac wiring to confirm that both the meter and the output are connected to the same output taps because many autoformers have multiple taps and can we wired to either increase or decrease range of the output voltage.

1b) If the variac is a modern solid state unit designed for lamp dimming, then the non-sine wave output will cause a normal AC voltmeter to read incorrectly. (Only an iron vane meter can correctly read the peak-clipped output from one of those.)

2) Does your variac, or your service bench, have a constant-voltage transformer in it?

2a) If yes, then the non-sine wave output of that transformer will cause a normal AC voltmeter to read incorrectly. (Only an iron vane meter can correctly read the peak-clipped output.)



In the meantime my question du jour has to do with L18, the horizontal size control. The schematic calls for an impedance of 35 ohms. It doesn't give it a value range though. Would 35 ohms be on the high side, or low side? The reason I ask is that my horizontal size control is at 3 ohms and spins, but does not adjust in impedance. Obviously broken . . . . .


3) Are you confusing impedance with resistance? If not, how are you checking inductance?

4) As a final suggestion, since Pittsburgh is a large city, see if you can find a volunteer who is familiar with 60 year old electronic circuits to double check both the value and wiring of your replacement capacitors.


It has been my experience that I can almost never find an error that that I made while repairing a circuit.

Please understand, in my 60 year involvement with electronic circuits, I have been tripped up by each of the above mentioned items.

James.

vts1134,

While it is possible that some component in the set has failed, you seem to have followed a logical step-by-step trouble shooting path and you have not located the problem. Let's do a little thinking out side of the box.

My favorite kind of thinking!


1) Is the variac that you are using an old fashion one with an autoformer and a mechanical slider in it?

Yes


1a) If yes, have you checked the output voltage with a different volt meter? It is possible that the built-in volt meter is off.

I hadn't until just now. It didn't occur to me that the meter could be off. Turns out it was. The built in meter reads low, 95v is actually more like 110v. 120v is more like 140v. Unfortunately with ACTUAL input voltages at line level the spark still happens in the 1X2, but ACTUAL input levels at 115 are ok. The last 10v on the input side are the killer.


2) Does your variac, or your service bench, have a constant-voltage transformer in it?

No


3) Are you confusing impedance with resistance? If not, how are you checking inductance?

I'm not sure what you mean here, so I probably am.


4) As a final suggestion, since Pittsburgh is a large city, see if you can find a volunteer who is familiar with 60 year old electronic circuits to double check both the value and wiring of your replacement capacitors.

It has been my experience that I can almost never find an error that that I made while repairing a circuit.

I do have some one locally that I could take the set to. I'm not sure I'm at that stage yet. If every one here is at that point with me then let me know and I'll cease my daily questions, no hard feelings :sadwave:.


Please understand, in my 60 year involvement with electronic circuits, I have been tripped up by each of the above mentioned items.

James.

I still run into things in my job that end up being a forehead slapper after hours of trouble shooting only to realize "press the power button" or any number of other day 1 lessons. It's always, always, always ok to "think outside the box" with me or "talk to my like I'm stupid" because I'll either learn something new or reinforce something I already know, either way I don't take offense.

Hey vts1134
Just for the heck of it, what voltage are the heaters getting? It should be a nominal 6.3 VAC (measured from point 'X' to ground). Is it signifigantly higher? Lower?

The reason I ask is that my horizontal size control is at 3 ohms and spins, but does not adjust in impedance. Obviously broken, but could this cause an over voltage situation on the fly? The schematic gives it two Majestic part numbers, they are B-1.533-1 and B-1.532-1. Does any know what these part numbers would correlate to on a replacement part?

I'm sorry this was a mistake. I'd edit my post but I think it's been up a bit too long. The coil is right on 35 ohms. Should it change impedance when it is adjusted though?

Hey vts1134
Just for the heck of it, what voltage are the heaters getting? It should be a nominal 6.3 VAC (measured from point 'X' to ground). Is it signifigantly higher? Lower?

6.3 pretty much on the nose on all tubes except V17- the damper, V18- the hv rectifier, and V19 the lv rectifier.

I'm sorry this was a mistake. I'd edit my post but I think it's been up a bit too long. The coil is right on 35 ohms. Should it change impedance when it is adjusted though?
You're reading DC resistance, and it will not change with the slug adjustment. The impedance (AC resistance) will change with the adjustment when there is an AC waveform across the coil.

The coil is right on 35 ohms. Should it change impedance when it is adjusted though?

Yes, it would if you measured it correctly.

If you measured it with an ohm meter, it would not change the value.

Confused?

Lets start this topic over again:

>>> Originally Posted by vts1134
In the meantime my question du jour has to do with L18, the horizontal size control. The schematic calls for an impedance of 35 ohms. It doesn't give it a value range though. Would 35 ohms be on the high side, or low side? The reason I ask is that my horizontal size control is at 3 ohms and spins, but does not adjust in impedance. Obviously broken . . . . . <<<

>>>Originally Posted by earlyfilm
Are you confusing impedance with resistance? If not, how are you checking inductance?<<<

>>> Originally Posted by vts1134
I'm not sure what you mean here, so I probably am.<<<

OK, let me ask a similar question in plain language.

If you have a coil of wire and measured the resistance and you and got, say 35 ohms.

You then measured the resistance with a powdered iron core inside it, the coil would still get 35 ohms.

You then measured it with your finger stuck through it, it still would read 35 ohms.

Why, because your VOM / VTVM measures your coil using simple direct current.

Do you agree?

Now, impedance is just the alternating current measurement of inductance with a few capacitor variables thrown in for good measure.

Inductance measures alternating current resistance, in this case, a very high audio frequency of just over 15,000 cycles per second (or Hertz.)

When the powdered iron core is inserted, the alternating current resistance (inductance) increases, but the direct current resistance remains the same.

Now about sticking your finger in the coil, is unknown, but it probably would raise the inductance, but not as much as the powdered iron core. However, depending on voltage involved, I must might not wish to test it that way. :-)

On the other hand, if you stick a brass rod in, it will lower the impedance (but not below it's direct current value).

OK, now your horizontal coil ain't nothing more than a coil of wire with an adjustable powdered iron core inside, and a capacitor connected over part of it or in resonance with it.

If you measured the horizontal coil with an ohm meter, just like my example, it too would not change.

How did you measure the coil?

How did you measure the coil?

I measured it's DC resistance, 35ohms.

From the "thought i'd seen it all" department, this has gotta be the first problem I've ever seen caused by the HV being too high in a BW set. Color sets, yes. But never a BW before this one. :no:
Anyhow, if adjusting the horiz. drive hasn't reduced the HV sufficiently, it's easy to cut back the gain of the output tube itself (the 6AV5). One method is to put a resistor in series with the cathode (say 100 ohms as a ballpark starting value). The other is to reduce the screen grid voltage (on pin 8). This is the method I would try first. Assuming you don't have a resistor decade box or a resistor assortment on hand, go to RadioShack (ugh:yuck: ) and get a card of 2.2K half-watt resistors. Locate the 5.6K screen grid resistor R84. Open one leg and insert a 2.2K resistor in series with it. Bring the set up and see what the HV reads. This will give you a ballpark indication of which way to go with R84, ie., whether it needs more resistance or less. If it needs more, add another 2.2K in series. If that's too much, you can make a 1.1K by paralleling a couple of the 2.2K.
The caveat is, if you succeed in getting the HV down and the arcing cured with the set at full line voltage, the width may be reduced too much. I'm betting the width will still be sufficient. If it's not, then a new plan of attack is in order. oc

I asked if vts1134 had double checked his input voltage:

My favorite kind of thinking!

Yes

I hadn't until just now. It didn't occur to me that the meter could be off. Turns out it was. The built in meter reads low, 95v is actually more like 110v. 120v is more like 140v. Unfortunately with ACTUAL input voltages at line level the spark still happens in the 1X2, but ACTUAL input levels at 115 are ok. The last 10v on the input side are the killer.



Your next step should be to connect your set to a DVD recorder or anything that will give you an analog RF output and bring up your set at lower-normal-voltage and adjust the set to get it working the best you can.

Once all the controls are set correctly, your still slightly too high voltage may correct itself.

Jas.

Once all the controls are set correctly, your still slightly too high voltage may correct itself.

Jas.
Possibly so. But the option of cutting the gain a bit on the 6AV5 may buy a little more headroom and require less 'brinksmanship'. oc

From the "thought i'd seen it all" department, this has gotta be the first problem I've ever seen caused by the HV being too high in a BW set. Color sets, yes. But never a BW before this one. :no:
Anyhow, if adjusting the horiz. drive hasn't reduced the HV sufficiently, it's easy to cut back the gain of the output tube itself (the 6AV5). One method is to put a resistor in series with the cathode (say 100 ohms as a ballpark starting value). The other is to reduce the screen grid voltage (on pin 8). This is the method I would try first. Assuming you don't have a resistor decade box or a resistor assortment on hand, go to RadioShack (ugh:yuck: ) and get a card of 2.2K half-watt resistors. Locate the 5.6K screen grid resistor R84. Open one leg and insert a 2.2K resistor in series with it. Bring the set up and see what the HV reads. This will give you a ballpark indication of which way to go with R84, ie., whether it needs more resistance or less. If it needs more, add another 2.2K in series. If that's too much, you can make a 1.1K by paralleling a couple of the 2.2K.
The caveat is, if you succeed in getting the HV down and the arcing cured with the set at full line voltage, the width may be reduced too much. I'm betting the width will still be sufficient. If it's not, then a new plan of attack is in order. oc

Decided to go with Bill's suggestion on this one. I stopped at my local antique electronic shop (sorry just couldn't bring myself to go to Radio Shack) and get myself a handful of resistors. After two hours of shooting the breeze with Don, which if you know Don is a very short conversation, I headed home ready to tackle the task at hand. It took two 2.2k resistors in series with R84 to bring the anode voltage down to the point where the 1X2 stops experiencing high voltage failure. At full line voltage the anode is still way over spec at 16kv, or at least that's what my meter and high voltage probe reads. There is no sign of high voltage problems any more, no sparking 1X2, no corona discharge around components in the hv cage, no black vertical lines on the screen. Tonight I go to sleep for the first time with a full screen raster :guitar::rockon::banana:. Granted there is no video, the horizontal isn't linear, and the screen is full of retrace lines but I'm pretty happy to be at this point :).
http://farm7.static.flickr.com/6018/5910098713_08016778e7.jpg
Just some questions/concerns at the end here.
Horizontal size and Horizontal linearity control slugs do nothing to the screen when adjusted.
Can some one tell me what Horizontal Drive and Horizontal AFC are/do?

One thing to check on the no video issue, is the detector diode(if it is not a tube). The SS diodes sometimes fail.

I am glad to see you have a full raster on your set and now you can run the set to fix the other problems. :thmbsp: What I would do first is hook up a signal source to the set, Give the tuner a good cleaning. Check all the tubes in the if section and clean all the pins on the tubes in the if. Does the brightness and contrast controls make any changes in the raster? If they do, The video may be getting to the crt. Try turning the horizontal hold control in both directions and see what changes that makes in the raster. I am sure you do not want to hear this, But go through and re check your work. Ask any one here and they will tell you the same thing. We ALL make mistakes and need to check over what we have done. Do it ten times if ya have to. Also make sure you take a rest from the set. Pick at the set a little at a time. You will be surprised at the ideas that will come to mind when you are rested and take your time at it.
Ed

Well son of a gun. Fancy that.:sing: First of all, is your set the version with the 'color converter socket' and "color switch" (M7)? If so, clean the heck outa that switch with contact cleaner since it's in the video signal path and could be killing the video if it's dirty.**
Also if the set has a phono input and a TV-phono switch (M6), good idea to clean that switch too while you got the squirt can going.


Can some one tell me what Horizontal Drive and Horizontal AFC are/do?
Drive adjustment is supposed to vary the amplitude of the signal going to the 6AV5's control grid.
AFC= automatic frequency control. One section of the 6SN7 (V15) serves the AFC function while the other section is the oscillator.

**Just like the 'service switch' in color sets. Ask Phil about that.:D:D

oc explains it better

There seems to be a design error here. The Sam's doesn't show what the HV is, but a 16GP4 typical operating voltage is 12KV. If they were actually operating it at 12KV, the Peak Inverse Voltage that the HV rectifier would see is slightly less than twice this. A little under 24KV.

The 1X2 is rated at 15KV PIV. So, it would break down. They're probably running the 16GP4 at 10KV or less, maybe 9.5KV. That would still cause the 1X2 to break down.

The 1X2-A, and 1X2-B are rated at 20KV PIV, the 1X2-C is rated at 22KV PIV.

If you can find a 1X2-A,B, or C then it would probably work without the modifications you made.

John