One of my New Years resolutions was to post better threads of my restorations. I've used Bandersen as my inspiration. I have enjoyed so many of his threads here both as they happen and through searching archived topics. This will not be a quick project for me, I plan on taking my time with this one, posting a lot of pictures of progress, and being very deliberate. With that in mind here is my new project, The RCA 621ts.
I found the set on ETF's classified pages and have been holding on to it for a few months. Now that the Holidays are over I decided that it's time to do some work on it.
The cabinet is the walnut finish. I understand it is considered less desirable than the mahogany or blonde finish, although I've read that it was made in fewer numbers than the mahogany.
http://farm8.staticflickr.com/7009/6631454431_dca07065fa.jpg
http://farm8.staticflickr.com/7152/6631452297_4b0eefcaf5.jpg
http://farm8.staticflickr.com/7034/6631459081_2155cf886b.jpg
The cabinet is original but not without it's flaws. It photographs better than it looks. There is some crazing on the lacquer and a couple of bad spots.
http://farm8.staticflickr.com/7029/6631472909_3d29fd6097.jpg
http://farm8.staticflickr.com/7154/6631470603_58630bb777.jpg
http://farm8.staticflickr.com/7018/6631482557_fcc26904cd.jpg
http://farm8.staticflickr.com/7158/6631475271_707271f9a8.jpg

After disassembling the set I think that some of the cabinet problems are due to sun fading. You can see in the picture below that the wood that was blocked from sun is much darker than the rest of the front.
http://farm8.staticflickr.com/7164/6631640629_6858372faf.jpg
Some other observations of the the cabinet were that some the screws holding in the safety glass seem to be non-original.
One original?
http://farm8.staticflickr.com/7160/6631492231_eeeb288e28.jpg
Both non-orignal?
http://farm8.staticflickr.com/7004/6631490049_e588a480f2.jpg
Also the safety glass itself is going to need to be replaced as it's flawed in between the two panes.
http://farm8.staticflickr.com/7175/6631678931_cb27f79474.jpg

The chassis was the usual dusty but in very good condition. No signs of rust any where to be seen.
Before.
http://farm8.staticflickr.com/7015/6631748493_e1755b53e9.jpg
http://farm8.staticflickr.com/7027/6631746317_d7396d854c.jpg
After.
http://farm8.staticflickr.com/7165/6631753531_9170802043.jpg
http://farm8.staticflickr.com/7023/6631758343_4f38432e3f.jpg

The Phillips screws are the correct ones for the retainers.

Something you might want to consider doing on this set is restuffing the old capacitors to keep it looking original.

Here are a couple pictures of mine, before recapping and after, hard to tell the difference!
I even replaced a green Solar brand cap from a later repair with one that matched the others.

I make a habbit of restuffing caps on sets that I either like alot or consider signifficant historically or as an example of something.

I will be restuffing ALL capacitors as well as replacing any components that may have been added through servicing this set back to their original look.
Thanks for the info on the Phillips screws on the clips, I'll have to source two replacements for the bottom clip. Were the screws holding the back on the set also Phillips, and were they brass colored?
Also thanks for the pictures of the bottom of the chassis, they will help in recognizing anything out of place on mine.

Great looking chassis. Word to the wise: cut a piece of heavy cardboard and cable-tie it over the speaker while you're working!

Great looking chassis. Word to the wise: cut a piece of heavy cardboard and cable-tie it over the speaker while you're working!

For sure, for sure, for sure. Or, you can tape it on with that blue masking tape. But for sure, something will find its way into that cone.

That's a real nice set. I personally like the faded look; the walnut grain shows though bettter. I sure wouldn't refinish that cabinet, maybe touch those worn spots with a little Deft brushing lacquer.

That is about as clean a chassis as one could hope for. Glad to hear you will be restuffing it. Keep us posted!

Great looking chassis. Word to the wise: cut a piece of heavy cardboard and cable-tie it over the speaker while you're working!

I wish you could have told one of the previous owners that. It seems that some one at some point damaged the top of the speaker.
I was a bit short on capacitors to finish the set so I put in an order today for the replacements that I was missing. I didn't want to start work on the set and have to stop because I don't have all the capacitors. Once my caps come in I'll start restuffing and share my steps.

That's a real nice set. I personally like the faded look; the walnut grain shows though bettter. I sure wouldn't refinish that cabinet, maybe touch those worn spots with a little Deft brushing lacquer.

I'm not sure what I'll do with the cabinet. Whatever I decide on I'll not be doing the work. My wood finishing skills end at 0000 steel wool and Howards Restor-a-finish.

Sounds like this will be a nice project to follow. I look forward to it...

A couple of updates.
The cabinet is now in the hands of the best wood finishing expert in the Pittsburgh area (or so I've been told by several trusting sources). He has been finishing wood for 58 years and has a small shop where he obsesses over his work in solitude. I had hoped to have the finished reamalgamated on the set but Lou thought the finish was too far gone for that method and that the crazing would return after only a few years. I know a few people here thought that the set shouldn't be refinished based on the pictures that I posted but the set photographed much better than it looked in person. I have ordered replacement decals from Radio Daze and will be applying them myself between the sealer and lacquer phases of the cabinet refinishing. One other bonus of refinishing is that the color will be able to be brought back to original, using the areas that were under cover as a reference. One question Lou had for me about the finish that I said I would answer later was the finish, should it be gloss, semi gloss, or something else possibly? What finish would the set have had from the factory? I would like to keep the set as close to what it would have looked like brand new.
I have also dropped off the safety glass to a local glass shop to have them cut a new piece for me. I expect that to come back next week.
On to the chassis. I have not done any component restoration yet, the electrolytics have not yet arrived so I've just been doing some further cleaning and polishing of the chassis. There were some non original decals on the rear of the set next to each control knob that were tough to remove. I tried scrubbing them off but I ended up having to sand them off in the end.
http://farm8.staticflickr.com/7023/6631758343_4f38432e3f_z.jpg
http://farm8.staticflickr.com/7033/6654698961_e646660ee6_z.jpg
Looking at pictures of Tom Albrecht's 621 I think that the labels for the rear control knobs were ink printed directly on the back panel. If this turns out to be the case I'll have to make templates and screen print them on. Can any one post some higher res pictures of their back with the labels so that I can get a font, location, and size?
Can some one also confirm what style and color the screws are for the back of the set?

I think it should be somewhat glossy, not mirror finish but a slightly reflective surface.

I think this picture of the unfaded area is about right.

http://farm8.staticflickr.com/7164/6631640629_6858372faf.jpg

I think the whole top cover, grille and the edges are supposed to be dark like this area.
http://farm8.staticflickr.com/7018/6631482557_fcc26904cd.jpg

Here's a picture of mine, note the shine on the curved edges and the dark trim, it's a Mahogany set though.
http://www.vintagetvsets.com/images/621.jpg

I think it should be ]somewhat glossy, not mirror finish but a slightly reflective surface.

I think this picture of the unfaded area is about right.

http://farm8.staticflickr.com/7164/6631640629_6858372faf.jpg

I think the whole top cover, grille and the edges are supposed to be dark like this area. http://farm8.staticflickr.com/7018/6631482557_fcc26904cd.jpg

Semi gloss then?
It's definitely a two tone color scheme with the top "hood," speaker grill, and side trim darker than the rest. I'm going to tell Lou to model the colors after the set in this picture.
http://farm5.staticflickr.com/4118/4866739809_f86a6f57c7.jpg

I went through the pictures sent to me by 621 owners participating in my 621 database, this is the only one that looked to be Walnut to me with an original finish.
The color scheme seems to be pretty similar to my Mahogany version, maybe a little lighter.

There seems to be a lot of variation among sets, some Mahogany ones are much darker than mine, there seems to be at least two different blond versions, and Walnut seems to be pretty rare.

Semi gloss then?
It's definitely a two tone color scheme with the top "hood," speaker grill, and side trim darker than the rest. I'm going to tell Lou to model the colors after the set in this picture.
http://farm5.staticflickr.com/4118/4866739809_f86a6f57c7.jpg

I think that would be about perfect, though that one looks to be refinished it's very nice.
I'm not sure if the top is supposed to be translucent like that one though, most seem to be pretty dark and opaque. Perhaps it's because it was outside in the sun?

I would aim for a darker finish on the top and trim, something similar to the knob color.
It probably has to be Toner, Paint won't look right.

Making progress with the electronic restoration now. I've got the first capacitor rebuilt. I used the tutorial posted in the tv and radio tech forum. I bent the bottom crimp up with a small flat blade screwdriver and popped the mounting ring out.
http://farm8.staticflickr.com/7034/6670342925_cc5871a979.jpg
Then I pulled the disk holding the terminals off of the rest of the can. In the process of pulling it off the paper cover on the can also came off, leaving me with four pieces.
http://farm8.staticflickr.com/7141/6670348391_df96080763.jpg
I then aranged the new electrolytic capacitors in a way that would fit inside the old can. I soldered the leads to the old terminals paying attention to make sure the values went to the corresponding terminals as they did originally.
http://farm8.staticflickr.com/7009/6670351141_5849f91412.jpg
The whole process was definitely time consuming and at times frustrating, but well worth the effort.
Before:
http://farm8.staticflickr.com/7154/6670344617_a55ca3e355.jpg
After:
http://farm8.staticflickr.com/7164/6670346105_2f31123c1b.jpg

Rebuilding the second capacitor was a bit more of a challenge than the first. Something was coating the underside of this cap, and the disk holding the terminals had become extremely brittle.
http://farm8.staticflickr.com/7025/6670347455_a5f506144c.jpg
I was not able to remove the disk without destroying it. I am now in need of a new terminal disk with three terminals to move on with rebuilding my next capacitor. If any one is able to sell me this odd small part please send me a message.

You can buy them from AES: http://www.tubesandmore.com/scripts/foxweb.dll/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?PAGE=SUBCAT&SEARCH_TREE01=CAPACITORS&SEARCH_TREE02=01_MOUNTING

Thanks for the link but that's not the piece that's broken. This part is.
http://farm8.staticflickr.com/7028/6670642655_3dc6d0dd5b.jpg

Ah, scavenge one from another cap then.

Semi gloss is a good choice for refinishing old sets. Modern full gloss looks too gaudy to me, and not at all representative of the original finish.

Ah, scavenge one from another cap then.

I'm not stocked up much on surplus parts. I'll try my local vintage electronic shop in the area, but if he doesn't have any then I may still need the help of a member here.

Semi gloss is a good choice for refinishing old sets. Modern full gloss looks too gaudy to me, and not at all representative of the original finish.

Semi it is. I have to see him soon as I need to drop off the pictures of the other sets that show the color scheme.

Semi it is. I have to see him soon as I need to drop off the pictures of the other sets that show the color scheme.

John,
You should only need to tell your refinisher what gloss level you want. There is no need to use flat or semi-gloss finishes.

Nitrocellulose lacquer finishes need to be sanded and rubbed out when done, so you can get any gloss level you want during the polishing stage. This is how it was originally done. Semi-gloss finishes use flatteners to obscure the gloss resulting in a weaker and somewhat cloudy finish. A gloss finish can be polished to any level while a semi-gloss can never be polished to a full gloss level. Also if you don't polish a gloss lacquer finish it will look "plasticy" and terrible.

Some refinishers today will use modern CAB or catalyzed lacquers which if sprayed in a dust free environment don't really require polishing, so a semi-gloss might look better, but it will still look cloudy.

Attached is a picture of my 621 that I refinished with gloss nitrocellulose lacquer and rubbed out with 0000 steel wool.

Darryl

John,
You should only need to tell your refinisher what gloss level you want. There is no need to use flat or semi-gloss finishes.

Nitrocellulose lacquer finishes need to be sanded and rubbed out when done, so you can get any gloss level you want during the polishing stage. This is how it was originally done. Semi-gloss finishes use flatteners to obscure the gloss resulting in a weaker and somewhat cloudy finish. A gloss finish can be polished to any level while a semi-gloss can never be polished to a full gloss level. Also if you don't polish a gloss lacquer finish it will look "plasticy" and terrible.

Some refinishers today will use modern CAB or catalyzed lacquers which if sprayed in a dust free environment don't really require polishing, so a semi-gloss might look better, but it will still look cloudy.

Attached is a picture of my 621 that I refinished with gloss nitrocellulose lacquer and rubbed out with 0000 steel wool.

Darryl

I wasn't even aware that there was different gloss levels to the actual lacquer. That wasn't even talked about when we discussed the refinishing. He simply wanted to know how I wanted it finished, not what kind of finish to use. He told me that he uses period correct lacquer on projects like this. I'm assuming he meant nitrocellulose but maybe I'll ask him now. I had originally told him to buff it to gloss, but I think I agree with those here who suggested semi so I'm going to tell him to go that way.
Lou was very backed up at the moment so I think that I'll have the chassis restored before I get the cabinet back from him. I did offer a little extra money to get the set done faster, if he takes me up on that offer then they might both be finished in a similar time.

Aww, man-All deze purdy Tellabishuns is makin' me GREEN w/envy...621s really WERE works of art, weren't they ?

Works of art indeed Sandy. I still like my GE 801 a bit more as far as aesthetics but the 621 is an amazing design.
I still haven't been able to find a replacement for the bottom of the electrolytic cap I broke, and not wanting to remove another multi-stage can until I finished that one, I decided to start on the paper caps. I was surprised at how much easier it was to restuff the paper caps than it was to rebuild the electolytics.
My wife got me a new soldering iron for Christmas so I used my old soldering gun to melt the old wax and cap out of the cardboard tube. Then I melted and cleaned the wax off of the outside of the tube. After I had a clean empty tube it was ready for the new cap.
http://farm8.staticflickr.com/7004/6687266605_63fc78a4bb.jpg
Perfect fit!
After putting the new cap inside the old housing I filled the ends with hot glue and shot a coat of lacquer on the cardboard to shine it up a bit and repel dust (the idea came from Hugo Holden's amazing 621ts restoration http://www.earlytelevision.org/holden_621.html, although he used varnish).
There was one cap in the horizontal output section that had been previously replaced with a modern cap. You can see my restuffed cap just to the right of it.
http://farm8.staticflickr.com/7158/6687267811_ee195f0400.jpg
Luckily I had saved all of the caps that I removed from the last set I recapped for just such an occasion and had a replacement value for it.
http://farm8.staticflickr.com/7174/6687268973_2e00393c9a.jpg
I restuffed a total of six caps tonight and honed my skill of filling the ends smoothly with glue towards the end. The rest of the paper caps should be no problem. You can see the six caps all towards the top of the picture below. I'm really happy with the look of restuffing versus just cutting the old caps out and replacing them with something that just doesn't look original. Well worth the effort!
http://farm8.staticflickr.com/7154/6687270115_9c9ac87a5f.jpg

I'm really happy with the look of restuffing versus just cutting the old caps out and replacing them with something that just doesn't look original. Well worth the effort!
That does have a nice appearance to it. I already use carbon composition resistors for all of my replacements, so I may try some paper restuffing on my CT-100. It has already had a bunch of its caps replaced in the past, but I kept all of the ones from the 8TS30 restoration so I could use some of those if needed.

I reciently started mixing some of the original wax in to container of hot glue to tint the glue a more original color. I then took pieces of the mix and melted them into the ends of the cap using a soldering iron. I used to take wax from other old caps and use it for restuffing, but once one has dismantled all spare junk caps for wax....cutting with hot glue seems logical (it also don't stink as much).

That was the only part I wasn't really happy with was the color of the glue at the ends. Any one ever tried a brown glue stick? A quick google search brought me this http://www.glu-stix.com/shop/page/product_detail/Product/10cecb953a44d31c22dac545b1ac34df.html. I have no concept of how much glue is in 5 pounds. Maybe we can do a group buy if it works.

Yes, I've been using brown and black glue sticks for a while with good results.

You can get them for a few bucks from various sellers on ebay (http://www.ebay.com/sch/i.html?_from=R40&_trksid=p3984.m570.l1313&_nkw=brown+glue+sticks&_sacat=See-All-Categories).

I got back under the chassis tonight. I'm still taking my time and making each and every action I take as deliberate as I can. I found another capacitor that was replaced at some later time.
http://farm8.staticflickr.com/7143/6698340501_a844816c27.jpg
You can see that there is a pretty large glob of solder on the connection point of that new cap. I've noticed shoddy work on the two obvious replacement parts in the set, both had way too much solder on the connections and you can clearly see that the repairman melted the insulation on a wire in the area when soldering a lead. You can see it on the left side of the picture below.
http://farm8.staticflickr.com/7158/6687267811_ee195f0400.jpg
One of the advantages doing one capacitor at a time and shooting each one with lacquer is that I have lots of time to survey the set as I wait for the lacquer to dry. One thing I noticed on one of these "breaks" was that R187(according to the Riders schematic), the high voltage rectifier winding resistor, is going to need to be replaced.
http://farm8.staticflickr.com/7161/6698339121_0b2ea95fd9.jpg
I'll file that in my noggin for later when I focus on resistors.
I still haven't been able to get out to my local antique electronic shop for a replacement multi-stage electrolytic cap to replace the one I snapped but I'm over half way finished with restuffing/replacing the paper caps. The top half of the set (as it sits on my bench) is now finished.
http://farm8.staticflickr.com/7169/6698337605_077341140f.jpg

Almost done with the paper caps and wouldn't you know it I'm short one value :sigh:. Put the order in yesterday for the replacement. I'm hoping to have the paper caps finished by the end of the week and move on to electrolytics by the weekend.
I did run into one capacitor value that I couldn't find a direct replacement for, .0025mfd. I used one .0015mfd and one .001mfd in parallel.
http://farm8.staticflickr.com/7145/6704702967_34b9918ac2.jpg
I used electrical tape to wrap each lead on each cap and then hot glued the two caps in place. Did any one else manage to find a direct replacement for these caps?

I thought I was the only one who restuffed caps with two in that fashion.

If the tube has a large enough diameter one can dispense with the electrical tape, and put the side of the case of one against the wire of the other.

I did run into one capacitor value that I couldn't find a direct replacement for, .0025mfd. Did any one else manage to find a direct replacement for these caps?
I used either .0022 or .0027 (and .022 or 0.22 in comparable cases) for that value and did not have a problem in my RCA 8TS30.

My supplier of capacitors only has .002 which would put it right at the edge of 20% so I decided to go exact replacement value. I'm pretty sure .002 would have worked but so will .0025 :).

I finished under the chassis tonight. All of the paper and electrolytic capacitors are re-stuffed and re-installed.
http://farm8.staticflickr.com/7174/6773470121_35be2f9314.jpg
I also replaced any bad, on the edge, and non RCA branded tubes with NOS RCA branded tubes (Four of the tubes are still not RCA branded, 1B3, 6SN7, 6BG6, and a 6H6, but I plan on finding RCA replacements for them).
http://farm8.staticflickr.com/7010/6773391167_7f506f2156.jpg
http://farm8.staticflickr.com/7001/6773392009_cf3086c7f8.jpg
At the end of a long day I decided to turn the bench off and wait for another day to apply power for the first time.

She's lookin' mighty purrty.:yes:

As Someone who knows NOTHING about the Electrical stuff...You GO , Kid...Save another 621 TS....We'll congratulllate you when the stuff separates out...

Fired the set up for the first time and got a surprise. C128B (one of the main filter caps) blew up in a cloud of foul smelling smoke.
**THIS IS IMPORTANT TO ANY ONE WHO WILL READ THIS AND START A RESTORATION OF THEIR OWN**
The Rider schematic has a misprint. It incorrectly states the value of C128B.
http://farm8.staticflickr.com/7008/6778437323_1e2c9a5be7.jpg
Why is this important? Because C128B is supposed to be rated at 450v not 150v and I'd like to save you the :mad: look your wife will give you when you smell up the house.
After replacing the offending capacitor I fired the set up again. No explosions :), however I didn't hear the horizontal oscillator so I investigated in that area. After swapping the 6SN7 out (it was one of the few non RCA branded NOS tubes) with another tube in the set I got the characteristic sound of the oscillator.
I took some voltage measurements and every thing was in the neighborhood so I installed the crt fired the set up and was greeted with.
http://farm8.staticflickr.com/7001/6779004645_bc8e8f6d7c.jpg
No video or sound just yet but it seems like a good time to quite for the evening.

I would restore this thing to CURRENT standards...it's too valuable to restore, IMHO, to 1946 standards...

That is the money shot of any vintage set as it tells you the electronic unobtainium is in good shape.

Great job so far!

And don't worry your not the only one whom has popped a freshly installed lytic. Heck I've done it twice now. LOL

And don't worry your not the only one whom has popped a freshly installed lytic. Heck I've done it twice now. LOL

I've done it once before also, but that was entirely my fault. Doing it because the schematic was incorrect is a bugger :rolleyes:. I'm sure it wont be the last time I run into that in my life and as I get better I'll be able to spot those mistakes before I make them. Had I analyzed the schematic and thought about where that capacitor was going/what it was doing instead of just going on faith I probably would have known it to be incorrect.

On multi-section cans I tend to check with the labeling of the can and the existant wiring to make sure of my work.

The first time I made that sort mistake I blew two lytics in a row because I could not find a way to get the chassis loose (the mounting nuts were recessed out of reach of a wrench), and a rubber AC mains line had disintegrated and shorted to one of the above chassis lytics.
The second time was a TV that I'd miss wired the replacements for the selenium doubler rectifiers on.....I was powering it up on a variac, went to have dinner, and started hearing a regular popping sound as the two sets of 5 22uF caps I had put in parallel to make up a replacement for each doubler cap started firing their guts out one by one.

Well I have run into my first stumper. I'm having a problem with the vertical. There's a short video of the problem in the link below (the set is on it's side btw).
http://www.youtube.com/watch?v=WXtdZeuZpO8
I've gone through the resistors in the vertical section and they all read within 20% of spec. I've also swapped the 6SN7 out. The problem kind of looks like the oscillator is running too slowly but the dual "rolling" lines have me stumped. Any one got any ideas?

What does it look like with a regular picture?

Looks like the vertical is not locked, and it's got a sine wave rolling through it. Scope the sync section, see if you can catch the sine wave. Could be a heater/cathode leak or short.

What does it look like with a regular picture?

I haven't gotten that far yet. There's no output from the tuner/if stages. I am working backwards from the crt. The picture above was injected at the grid of the video amp. If you're asking for the same reason I wished I had a regular picture, to see if there is two complete pictures on the screen, then the answer is yes. One of the patterns available on my video injector is three horizontal lines. When I select this setting I get six lines on screen, with the "rolling" hum bars separating them. This is what makes me think that my oscillator is running too slowly.

If you adjust the vert hold control, will it lock to the hum bar? Or does the bar still "roll" irrespective of the v hold setting?

It's tough to explain, when I adjust the vert hold it will start to roll the way sets normally do when you are out of vertical lock. Then I can get it to "lock" on the horizontal bar but it still rolls slowly in the way that you can see in the video. One thing I noticed is that the voltage on the grid of the vertical output (pin 4) moves up and down 5-6 volts in tune with the rolling bars.

Sounds like a heavy power supply ripple is getting into the vert circuit. Possibly one of the filters is miswired(?).

I'll buy that for a $. I'll give a third look at every filter cap and see if I can't find an offending miss-wire by yours truly.

The video reminds me of when my 1953 Zenith had it's vertical working at double frequency.

Have you made sure all resistors in the vertical are in tolerance? Those can really louse things up if they have drifted too far off value.

The video reminds me of when my 1953 Zenith had it's vertical working at double frequency.

Have you made sure all resistors in the vertical are in tolerance? Those can really louse things up if they have drifted too far off value.

I have gone through the resistors in the vertical. I even drew the circuit out as I worked through it. That of course is no guarantee that I didn't miss something, but they all tested within 20%.

Sounds like a heavy power supply ripple is getting into the vert circuit. Possibly one of the filters is miswired(?).

Checked and rechecked the filters for a miswire but came up empty. I've gone through the resistors from the sync tube through the vertical output tube and they are all where they need to be. This one's a real :headscrat.

What does it look like with a regular picture?

I recently acquired a B&K 1077 so I can show what a regular picture looks like now. I had prevously thought that the vertical was running too slowly but you can see now that is not the case. The horizontal white bands do not roll with this signal, instead they are steady right where you see them.

http://farm8.staticflickr.com/7004/6824214291_93536124b3.jpg

Any thoughts?

I know you have probably checked this but going by just the picture it looks like a power supply cap has let go.

...I recently acquired a B&K 1077 so I can show what a regular picture looks like now. I had prevously thought that the vertical was running too slowly but you can see now that is not the case. The horizontal white bands do not roll with this signal, instead they are steady right where you see them.
It sure looks like a huge power supply ripple. The bars not rolling would be the case if the B&K's vert sweep is locked to the powerline (whereas a TV station's vert is offset slightly, which would cause the bars to roll). Possibly one of the replacement filters has gone open.

If you've got an extra 'lytic cap of equivalent rating as the main filters, you can jumper each one and see if the ripple disappears.

Or alternately if you have an analog AC voltmeter, you can measure ripple. Just put a cap of .1mf or so in series with the meter's hot lead (to block the DC component). I'm not sure i would trust a digital meter in that application.

It sure looks like a huge power supply ripple. The bars not rolling would be the case if the B&K's vert sweep is locked to the powerline (whereas a TV station's vert is offset slightly, which would cause the bars to roll). Possibly one of the replacement filters has gone open.

If you've got an extra 'lytic cap of equivalent rating as the main filters, you can jumper each one and see if the ripple disappears.

Or alternately if you have an analog AC voltmeter, you can measure ripple. Just put a cap of .1mf or so in series with the meter's hot lead (to block the DC component). I'm not sure i would trust a digital meter in that application.

I did try adding a cap to each of the electrolytics except for the 1,000mfd cap as I do not have a replacement for it.
How would I measure ripple with an analog meter? I have an analog VTVM and a .1mfd cap. That is to say what would I look for?

I did try adding a cap to each of the electrolytics except for the 1,000mfd cap as I do not have a replacement for it. How would I measure ripple with an analog meter? I have an analog VTVM and a .1mfd cap. That is to say what would I look for?
First i think it'd be a good idea to see perzackly what's connected between the center tap of the power xfmr and ground. Some of those filters' negative sides are insulated from ground and are connected to the CT. Just for the heck of it, take a resistance reading from that CT to ground. How much resistance does it show? If by chance it's inadvertantly shorted to ground, there would be some hairy ripple and hum bar effects.
In that pic of the power supply area that you posted earlier, it doesn't show where the center tap goes to (kinda fades into the twilight zone). Is it possible you could post a pic showing more of that area?

I've got some readings on the electrolytics and a better picture of the schematic.
http://farm8.staticflickr.com/7157/6829564185_577fae063e.jpg
There are 5 multi stage electrolytic capacitors in the set. Towards the top of the picture, just above, and just to the right of the vertical centering control you can see two sections of C116. The negative on this cap reads shorted to ground which according to the schematic is correct. The other four caps are isolated from ground. Coming right off the center tap of the power transformer is the negative leads of C127, C128, and C131. Further along the line you have C132. Rather than give it away, how would I read the schematic and figure out what resistance reading those four caps should have to ground?

I've got some readings on the electrolytics and a better picture of the schematic.

There are 5 multi stage electrolytic capacitors in the set. Towards the top of the picture, just above, and just to the right of the vertical centering control you can see two sections of C116. The negative on this cap reads shorted to ground which according to the schematic is correct. The other four caps are isolated from ground. Coming right off the center tap of the power transformer is the negative leads of C127, C128, and C131. Further along the line you have C132. Rather than give it away, how would I read the schematic and figure out what resistance reading those four caps should have to ground?
Hmm.. so the power xfmr CT is the negative voltage source*, supplying 110V negative for stuff elsewhere in the chassis. And the main filter for it is the 40mf.cap (square symbol). Can't read it too good, but i b'lieve it's C128A). The positive side of this cap should go to ground. Is this wired correctly? If it's not, the negative supply would have a large ripple on it. So check this first, and then check for ripple. And verify that there's 110V negative on it (+/- 10% or so).

To check resistance of the -110V source to ground, just look for a DC path to the nearest ground symbol in the schematic (hint: it goes thru the ion trap coils), and add up the values of the resistances in that path. And see if the sum agrees with the ohms reading you get on the meter (+/- 10% or so).
------------------------------------------
*This technique is called "back biasing". You'll find it used in old equipment quite often, particularly in 30s radios. The CT of the power xfmr winding, instead of going directly to ground, goes through a chain of resistors or a large tapped resistor to form a voltage divider, supplying negative voltages for biasing other tubes in the set. A Google under "Back bias voltage" should turn up some good info on it.

To check resistance of the -110V source to ground, just look for a DC path to the nearest ground symbol in the schematic (hint: it goes thru the ion trap coils), and add up the values of the resistances in that path. And see if the sum agrees with the ohms reading you get on the meter (+/- 10% or so).


Such an easy answer to my question. Seems silly that I had to ask, but now I know. All of the resistance readings on the negative sides of the capacitors read correctly.

Hmm.. so the power xfmr CT is the negative voltage source*, supplying 110V negative for stuff elsewhere in the chassis. And the main filter for it is the 40mf.cap (square symbol). Can't read it too good, but i b'lieve it's C128A). The positive side of this cap should go to ground. Is this wired correctly? If it's not, the negative supply would have a large ripple on it. So check this first, and then check for ripple. And verify that there's 110V negative on it (+/- 10% or so).

This is wired correctly, and there is -110v present.
I believe that I am checking for ripple, but perhaps I have the test wrong. I have put my meter on an AC 4v scale. I've connected the ground lead to chassis ground and the probe through a .1mfd cap to negative on C128. Is my test correct, and am I seeing ripple on the meter?
http://www.youtube.com/watch?v=b5BBxQlqp1o

Yes your hookup is right. It's showing just a little over 2VAC of ripple. That shouldn't be anywhere near enough to cause the huge hum bar effect you're seeing. This pretty well eliminates the negative supply as the source of the problem.

So check for ripple on the positive supply, first on the 'upstream' side of the spkr field* coming out of the rectifier (there'll be a large ripple here) and then on the 'downstream' side (top of C127A). Then at the top of C116B. The ripple should smooth out to just a volt or two and get progressively smoother the further downstream you go, such as at C116A.
-------------------------------------
*The speaker field serves double duty as a filter choke, a common practice in old equipment.

Check for ripple on the positive supply, first on the 'upstream' side of the spkr field* coming out of the rectifier (there'll be a large ripple here) and then on the 'downstream' side (top of C127A). Then at the top of C116B. The ripple should smooth out to just a volt or two and get progressively smoother the further downstream you go, such as at C116A.
-------------------------------------
*The speaker field serves double duty as a filter choke, a common practice in old equipment.

Yep, this is exactly how the set is behaving. Progressively less AC as I move further downstream. By the time I get to C116A the ripple is less than a volt. A real :headscrat for sure.
I thought outside the box today and considered that there was outside interference so I unplugged my LED work light transformer and every thing else on my bench to see if the problem was external to no avail.

Have you considered an H-K short in the CRT?

By golly it looks like power supply ripple has been pretty decisively ruled out. I went back and reread the thread and looked more closely at the pics. Post#43 shows the raster as having nice straight sides (no hourglassing), indicating no appreciable ripple in the B+ feeding the H output stage (good). And post#58 shows the CRT displaying strong video which would rule out a heater-cathode short in the CRT (which would kill the video).

So.. it kinda looks like the hum is arising somewhere in the video chain 'upstream' of the CRT. And since the sync is affected too, the hum must be occuring upstream of the sync take off point. (Just guessing, but the sync may be picked off at the vid. output which was common practice in the old stuff.) It could possibly be nothing more than a H-K short in a tube. Sometimes tapping the tubes will show up an intermittent that won't show up on a tester.
If it ain't a tube, maybe you could post a pic showing the video amp and sync areas of the schematic.

Occam's Razor: you've been making cap upgrades which means you've been messing with the wiring, find the wiring fault and repair it.

Finding the wiring fault can be fun and challenging if you make it so. :)Also helps a Noob hone his skills. Sorta like in the old days an electronics instructor would deliberately introduce a fault into a piece of gear.

Tell me about it. When I went through AE 'A' school in Pensacola, I was forever finding faults with their trainers. Then again, they were as old as most of our sets...

Check your work young student! Good advice for every restoration and I should have done it sooner. I traced every wire on every connection that I had my hands on and three hours later I'm vindicated but sad to report that I have not found a single wire/connection out of place.
I tried a few taps on each tube and no changes there. Maybe I can retest the tubes for HK shorts.


So.. it kinda looks like the hum is arising somewhere in the video chain 'upstream' of the CRT. And since the sync is affected too, the hum must be occuring upstream of the sync take off point. (Just guessing, but the sync may be picked off at the vid. output which was common practice in the old stuff.)...
If it ain't a tube, maybe you could post a pic showing the video amp and sync areas of the schematic.

It looks like the sync is taken off of the plate of the 2nd video amplifier. The video at this point carries the sync pulses with it to the sync amplifier which would magnify these signals. The sync separator would remove the sync pulses from the video (or does the term "separate" come from separating the horizontal pulses from the vertical?) and pass them on to the vertical and horizontal output sections. If this is correct and the problem is originating in the video section, is there a way to isolate every thing upstream from the 6SN7 sync amp/separator to quickly confirm this? Would removing the video amplifier tube achieve this?
I could be completely off base on my thoughts above but just trying to think it out as much as I can on my own so I can learn.

http://farm8.staticflickr.com/7027/6838598171_e06ab1ee59_z.jpg

http://farm8.staticflickr.com/7025/6838599141_a55bb984c5_z.jpg

is there a way to isolate every thing upstream from the 6SN7 sync amp/separator to quickly confirm this? Would removing the video amplifier tube achieve this?

You can isolate everything from before the video amp by lifting the grid connection (V105 pin 1), then injecting composite video right into the video amp on pin 1. If the problem goes away, the issue is in the tuner/IF. If you remove the sync tube, the picture won't lock at all and I think it would be difficult to tell if there problem were still there or not.

One last thought.
If the problem is coming from the video section would it still manifest itself with no video signal present?

One last thought.
If the problem is coming from the video section would it still manifest itself with no video signal present?
Yes it would, assuming the raster has still got that heavy white bar in it. That bar's still present, right? If it is, there's another trick you could use that doesn't involve lifting any connections or injecting a signal (the bar is the "signal"). Get that trusty .1mf cap again* and hook one end to ground, and the other end to a clip lead. Starting with G1 of the CRT (this set injects video via the grid instead of the cathode), and connect the cap to it. This shorts the signal and should produce a blank or near-blank raster. Then take the clip lead and progressively work back, shorting the plate of the 2nd video stage, then the grid, then the plate of the 1st video, then the grid, and on back through to the plate of the 6H6 and then the cathode. If at any point the bar remains unaffected, you'll know it's originating in the stage you just left, 'downstream' of the shorting cap.

Be sure and discharge the cap to ground after taking it off the plate of a tube!
-------------------------------------
*If the single cap is not killing the bar sufficiently, and if you have more than one of those .1 caps, put as many as you can in parallel to get higher capacitance for better shorting effect.

When you say blank raster, do you mean just a normal raster minus my white bar problem?
Shorting (through a cap) G1 to ground makes no change in raster. .1 didn't do it so I moved to .25 which didn't do it so I jumped all the way up to 10mfd which also had no change, aside from the fact that it was a bit more dramatic to discharge. Assuming I didn't do this test wrong would that put the problem in the CRT?
Fearing I did the test wrong I injected my pattern generator on the video amp to ensure that when I shorted G1 to ground that the video went away, which it indeed did.

Da-yum. You're sayin' that even with the CRT's G1 clamped to ground with a 10mf cap, the white bar remains unchanged? That means the bar is definitely not originating in the video chain (see how one quick test can eliminate or confirm a whole signal chain?:)). Does the bar roll if you turn the vert hold control or not? I'm gonna take a SWAG that the bar is locked to the vert sweep, in which case it will not roll. And another guess that the bar is actually appearing on the CRT's G2.. and that since G2 has boost voltage on it, something's allowing vertical pulse to get into the boost source.

Try this- do the ripple test thingy again with the .1cap, on the CRT's G2. I'll betcha there's some signifigant ripple there, causing the white bar.

Of course i could be completely wrong. :worried:

The CRT appears to have a partial aquadag coating on it. Is that coating securely grounded? An ungrounded or poorly grounded 'dag can cause some really weird symptoms mimicking sync and AGC problems (a little factoid worth bookmarking).

Oldcoot88: "Is that coating securely grounded? An ungrounded or poorly grounded 'dag can cause some really weird symptoms mimicking sync and AGC problems (a little factoid worth bookmarking)."

Good one! A spring arcing in a curb-found 1961 Philco BW, left the room, and the CRT "blowed up". Made a hell of a mess out the back. Cant be too careful grounding.

...A spring arcing in a curb-found 1961 Philco BW, left the room, and the CRT "blowed up". Made a hell of a mess out the back. Cant be too careful grounding.
Dang.:eek: First time i heard of that happening (other than those SS color Zeniths with the 4-legged Safety Cap which would fail, letting HV soar to over 50KV, cutting the neck off the picture tube).

Da-yum. You're sayin' that even with the CRT's G1 clamped to ground with a 10mf cap, the white bar remains unchanged? That means the bar is definitely not originating in the video chain (see how one quick test can eliminate or confirm a whole signal chain?:)). Does the bar roll if you turn the vert hold control or not? I'm gonna take a SWAG that the bar is locked to the vert sweep, in which case it will not roll. And another guess that the bar is actually appearing on the CRT's G2.. and that since G2 has boost voltage on it, something's allowing vertical pulse to get into the boost source.

Try this- do the ripple test thingy again with the .1cap, on the CRT's G2. I'll betcha there's some signifigant ripple there, causing the white bar.

Of course i could be completely wrong. :worried:

The CRT appears to have a partial aquadag coating on it. Is that coating securely grounded? An ungrounded or poorly grounded 'dag can cause some really weird symptoms mimicking sync and AGC problems (a little factoid worth bookmarking).

The white bars roll right along as I adjust the vertical hold out of lock, and back in place when I adjust the vertical into lock.
I'm not sure how much ripple would be needed to cause a symptom like that but G2 has in the neighborhood of 3VAC present on it without any signal injection.
The aquadag still looks intact and making connection to ground, looks can be decieving though I'm sure. Is there a good way to test it's connection to ground to rule it out?
What a mystery we have. Maybe it was the butler in the library with a pipe wrench?

LOL. Here is a clue on that aqua dag check. If you use the grounded screw driver CRT technique to discharge the HV, then use the same tools set up the same and with the set on touch the blade of the screwdriver to the aquadag coating in a few spots and if you get an arc or spark then the CRT's dag ain't properly grounded. Might also be able to use a HV meeter instead of a screwdriver.

Awhile back I accidently confirmed I had this issue on my CTC4 with my hand.....it shook me up and made me swear like a pirate. 25KV can certainly alter ones vocabulary and mood.

The white bars roll right along as I adjust the vertical hold out of lock, and back in place when I adjust the vertical into lock.
I'm not sure how much ripple would be needed to cause a symptom like that but G2 has in the neighborhood of 3VAC present on it without any signal injection.
Well that rules out G2 and leaves only the cathode of the CRT. Try this for the heck of it- hook that 10mf electrolytic from ground to the cathode (observing polarity of course) and see if the bar remains.

One other thought- After doing the cathode shunt, try shunting G2 with the 10mf cap. Hook its neg. end to top of C116B (which carries smoothest B+) and the positive end to G2. This will effectively kill all ripple on G2, just in case the 3VAC is sufficient to cause the bar.

Maybe it was the butler in the library with a pipe wrench?
Maybe he was in the library with a wench.

:tongue:

Well that rules out G2 and leaves only the cathode of the CRT. Try this for the heck of it- hook that 10mf electrolytic from ground to the cathode (observing polarity of course) and see if the bar remains.

One other thought- After doing the cathode shunt, try shunting G2 with the 10mf cap. Hook its neg. end to top of C116B (which carries smoothest B+) and the positive end to G2. This will effectively kill all ripple on G2, just in case the 3VAC is sufficient to cause the bar.


Negative on both counts :sigh:.
I also did the grounded screwdriver trick to spots on the dag with the set on to check grounding of the crt and it was ok.
Could it be the tube itself?

I'd try running the filament of the CRT on it's own transformer to rule out hum leakage from a heater-cathode short.

Interesting suggestion. What kind of amperidge would that need? The schematic calls for 8A on the heaters for everything else, but no rating on the CRT filament.

I don't know the exact specs, but probably around 800mA should be enough. As long as the filament is not running more than 1 volt high or low it should be safe for a quick test.

The CRT heater already has its own dedicated 'floating' winding in the power xfmr, designated 'Y and YZ', going to 'KIN' (for kinescope, the archaic term for CRT).

Try this- unplug the CRT from the socket and check for heater to cathode short with the ohmeter on highest range. It should read infinity (although a short might occur when the heater warms up). Also check DC resistance form the floating winding to ground. It should also read infinity, but double check the schematic to verify this, and that it's not connected to B+.

With the set on (and the CRT reconnected), measure the DC voltage between heater and ground, and see if it reads the same as the cathode (or not). Ideally, it should not if it's truly 'floating'. Then try shunting the heater to ground with the 10mf cap, first from one side of the heater and then the other. And see if the bar remains.

The CRT heater already has its own dedicated 'floating' winding in the power xfmr, designated 'Y and YZ', going to 'KIN' (for kinescope, the archaic term for CRT).

Try this- unplug the CRT from the socket and check for heater to cathode short with the ohmeter on highest range. It should read infinity (although a short might occur when the heater warms up).

It reads infinity on the Megohm scale.

Also check DC resistance form the floating winding to ground. It should also read infinity, but double check the schematic to verify this, and that it's not connected to B+.

It has a path to ground, but it's connected to B+

http://farm8.staticflickr.com/7061/6860012135_c854c8e988.jpg

With the set on (and the CRT reconnected), measure the DC voltage between heater and ground, and see if it reads the same as the cathode (or not). Ideally, it should not if it's truly 'floating'.

It reads a different voltage than the cathode. Heater reads +225V and cathode reads +195V, which I see is a little low so I took a measurement where it should read +425V and it only got +350V. It's right on the 20% mark but it looks like I'll be going resistor hunting at some point to address that.

Then try shunting the heater to ground with the 10mf cap, first from one side of the heater and then the other. And see if the bar remains.

:no: The bar wins this round.

Why is the heater connected to HV? Is that to reduce the potential and the arcing possibility between it and the cathode?

. . . . . . I had prevously thought that the vertical was running too slowly but you can see now that is not the case. The horizontal white bands do not roll with this signal, instead they are steady right where you see them.

http://farm8.staticflickr.com/7004/6824214291_93536124b3.jpg



VTS1134,

OldCoot is suspecting one problem, and he very well may be correct.

Let's stop and think about the problem.

I see the vertical section attempting to run at 120 cps and it is badly speed modulating the sweep resulting in dual white bands. In other words, the normal 60 cps sawtooth is being speed modulated by a two backwards steps at a frequency of 120 cps.

The wrong speed operation could be caused by either a 120 cycle hum being fed to it from the power supply or from some component in the vert osc/output circuit being badly off value. (A heater cathode short would introduce a single band. Only the 120 cps hum can create a double band and 120 usually is only found in a full wave power supply.)

1) I assume that you do not have a service scope. If you do, the first thing to check is the B+ and B- power supply sources for hum. Then check to see if the waveforms from the sync separator through the vertical output are correct.

2) Substitute the vertical tube. If you don't have a spare, switch the video output 6SN7 with the vertical output 6SN7 tube. If this changes your problem, then you probably have a bad vertical output tube.

3) Since you restuffed the electrolytics, you might check to confirm that no electrolytic can became accidentally grounded. None of the original electrolytic cans in either the power supply or the vertical section were grounded when RCA built the set.

4) Check every electrolytic in the vertical to make sure you have a close to correct value and it is wired in with the correct polarity. On the Riders on the ETF website, which I've copied in an attachment, the positive side of the electrolytic is always marked with the section marker (ie, the triangle, square or inverted cup). Especially, check C127B between the height control wiper and the 100K going to the wired end of the vertical hold. Another possible source is an incorrect electrolytic across the cathode resister of the vert output. Also check C131B at the vert output transformer.

5) If you had a real mess up in the front end of the power supply you would hear a rather annoying buzz from the speaker, as the field coil of same is used as the filter choke. (If you have a loud hum, then pull the audio output tube and if it continues, then there is a problem in the power supply.)

Hope something here helps.
James

Why is the heater connected to HV? Is that to reduce the potential and the arcing possibility between it and the cathode?
Exactly.

:saywhat:By golly now that we got more of the schematic to eyeball, there's one more CRT element, the focus electrode or "G3" that hasn't been shunted with the .1 (or .25) cap.
Try clamping it, with the cap going from B+ to "G3" (pin 6). If the bar still remains, Mr. Earlyfilm has an idea i hadn't thought of yet:
VTS1134,

I see the vertical section attempting to run at 120 cps and it is badly speed modulating the sweep resulting in dual white bands. In other words, the normal 60 cps sawtooth is being speed modulated by a two backwards steps at a frequency of 120 cps.
Hah. "Speed modulation" of the v sweep waveform itself. That's an idea worth exploring.
IIRC, VTS1134 has a variac. While troubleshooting a vert problem in his vintage Majestic set, the idea was floated of driving the vert. yoke winding directly with the variac. Even though it's a pure sine wave, if it were tried on this set, it would at least reveal whether the bar is sweep derived (ie., 'speed modulated' sweep) vs. a rogue pulse on one of the CRT elements.

:saywhat:By golly now that we got more of the schematic to eyeball, there's one more CRT element, the focus electrode or "G3" that hasn't been shunted with the .1 (or .25) cap.
Try clamping it, with the cap going from B+ to "G3" (pin 6).

The focus anode is sitting at around 1500V so even bypassing to B+ is still way over 1000V. Better have a cap rated for this.

I wuz just goin' by the schematic which calls for approx. 495V (varies with focus control setting).

I'm not sure why they show that. The voltage on the focus anode is going to vary between 1475V and 2250V based on the resistor values shown. The RCA spec sheet for the 7DP4 says it should average around 1800V for 7500V operation. Definitely need to use cation and a high voltage cap.

Darryl

...(CRT) cathode reads +195V, which I see is a little low so I took a measurement where it should read +425V and it only got +350V. It's right on the 20% mark but it looks like I'll be going resistor hunting at some point to address that.
Actually the exactitude of these voltages is not all that important as long as you have a bright, in-focus pic and the brightness control has proper range. Having the proper bias relationship between K and G1 is what's important, not so much the voltages themselves relative to ground.

I'm not sure why they show that. The voltage on the focus anode is going to vary between 1475V and 2250V based on the resistor values shown. The RCA spec sheet for the 7DP4 says it should average around 1800V for 7500V operation. Definitely need to use cation and a high voltage cap.

Darryl
Good call. Maybe it's a misprint of 1495V.:saywhat:

Thank you for your thorough and thoughtful insights. I can answer a couple of things right away.

1) I assume that you do not have a service scope. If you do, the first thing to check is the B+ and B- power supply sources for hum. Then check to see if the waveforms from the sync separator through the vertical output are correct.

I have inherited a scope but it is badly out of calibration, and the probe is questionable at best. After reading a few period TV servicing books from front to back two or three times, and with several more on the way I have strengthened my resolve to acquire a working scope and learn how to use it. Unfortunately this doesn't help me currently.
One thing to note about the vertical sync pulses: I performed the following test. I disable the vertical osc by shorting the the grid to cathode and injected vertical grid pulses directly at the grid of the vertical output from my B&K television analyst. My thoughts were to isolate the output from the oscillator to see if the problems came from the sync/osc stage, or elsewhere. I'm not sure if I would have totally isolated the problem as being sweep derived (as OC suggested with the variac test), but the two white bars remained.




2) Substitute the vertical tube. If you don't have a spare, switch the video output 6SN7 with the vertical output 6SN7 tube. If this changes your problem, then you probably have a bad vertical output tube.


I had previously swapped the 6SN7s around in the set and the problem was unchanged.


3) Since you restuffed the electrolytics, you might check to confirm that no electrolytic can became accidentally grounded. None of the original electrolytic cans in either the power supply or the vertical section were grounded when RCA built the set.

I'll check on this.


4) Check every electrolytic in the vertical to make sure you have a close to correct value and it is wired in with the correct polarity. On the Riders on the ETF website, which I've copied in an attachment, the positive side of the electrolytic is always marked with the section marker (ie, the triangle, square or inverted cup). Especially, check C127B between the height control wiper and the 100K going to the wired end of the vertical hold. Another possible source is an incorrect electrolytic across the cathode resister of the vert output. Also check C131B at the vert output transformer.


I'll recheck all of the lytics, but I can tell you with certainty that 127A and B is polarity and value correct (in so far as the markings on the cap itself). It was one of the cans that I uninstalled and checked twice. Also R145, the 100K resistor going to the wired end of the vertical hold, checks ok. I'll recheck the other two capacitors tomorrow just to be sure.


5) If you had a real mess up in the front end of the power supply you would hear a rather annoying buzz from the speaker, as the field coil of same is used as the filter choke. (If you have a loud hum, then pull the audio output tube and if it continues, then there is a problem in the power supply.)


There is no buzz or hum in the speaker. I get audio output on channel 2 through my television analyst and what sounds like FM on channel 1.

I'll report the other findings tomorrow. Also if I have time in the day tomorrow I'll have some pretty pictures of the cabinet to share as I put some decals on.

Re: +495 volts on focus anode on schematic

I'm not sure why they show that. The voltage on the focus anode is going to vary between 1475V and 2250V based on the resistor values shown. The RCA spec sheet for the 7DP4 says it should average around 1800V for 7500V operation. Definitely need to use caution and a high voltage cap.

Darryl

Darryl,

RCA specified that all voltage readings were to be read with a Voltohmyst. Those meters were very sensitive service meters for the era and only have a 11 meg ohm per volt circuit load on DC. The WWII era Voltohmyst was limited to 1,000 volts DC, without the high voltage attachment. (Confirmed by the manual for my RCA 195-A, although the meter scale goes higher. Duh ! )

Note the little asterisk beside the +495 volts on the schematic.

The asterisk means they specified that pin 6, the focus anode, was to be measured only with the brightness control turned fully counterclockwise. This would bias the Kinescope to cutoff.

I suspect cutoff would drop the focus voltage to within the range of the Voltohmyst. It also would increase the 2nd anode voltage to 7,500 volts, which most 1946 service shops could not measure.

This has nothing to do with curing the present vertical problem, but once the set is operational, it would be an interesting experiment to perform, since the focusing anode voltage dropping with beam cutoff, goes against conventional logic.

James.

Sounds like this will be a nice project to follow. I look forward to it...

I was looking at all the entries. Thanks to all that provided all those excellent pictures. I'm not sure what approach I'm going to take on my set. I see all the high value resistors that probably need changing, as well as the caps.:scratch2:

Re: +495 volts on focus anode on schematic

Darryl,

RCA specified that all voltage readings were to be read with a Voltohmyst. Those meters were very sensitive service meters for the era and only have a 11 meg ohm per volt circuit load on DC. The WWII era Voltohmyst was limited to 1,000 volts DC, without the high voltage attachment. (Confirmed by the manual for my RCA 195-A, although the meter scale goes higher. Duh ! )

Note the little asterisk beside the +495 volts on the schematic.

The asterisk means they specified that pin 6, the focus anode, was to be measured only with the brightness control turned fully counterclockwise. This would bias the Kinescope to cutoff.

I suspect cutoff would drop the focus voltage to within the range of the Voltohmyst. It also would increase the 2nd anode voltage to 7,500 volts, which most 1946 service shops could not measure.

James.

James,
Something still doesn't add up. The focus voltage does not change much over the full operating range of the crt as the load is negligible. The RCA manual does indeed say that besides the Junior Voltohmyst you need the optional high voltage probe which allows measurements to 10KV. That must have been used only for the 7500V measurement as the Voltohmyst was capable of 1000V on it's own, so if the 495V is correct, the meter was used without the HV probe.
The loading of the meter is a fixed 11meg, not 11meg/volt, but even with this extra load, and with the focus control turned to the low side you still end up with 966V. With the control to the high side you get 1250V. I'm still guessing this was a misprint in the original RCA manual and just got duplicated in Riders and elsewhere.

I suppose one of us could go measure it on a working set. Since modern meters are 10M input impedance, any digital or VTVM should work.

Darryl

Well I did have some time today to apply the decals to the set. There were a few coats of lacquer applied to the set to smooth out the surface. There will be many more coats applied now to bury the decals into the finish. I was surprised to find out that the finisher never uses grain filler, instead he simply shoots lacquer and sands until he gets a glass smooth finish (if that is the goal). I'm very happy with the progress so far and can't wait until I see the finished product.

http://farm8.staticflickr.com/7040/6871111899_fdf0407663_z.jpg

http://farm8.staticflickr.com/7196/6871106269_41ca9ee826.jpg

The sides of the set are a bit darker than the front and top. I would have been happier if they were the same color. The lighting accentuates this fact a bit more than what it looks like in person.

http://farm8.staticflickr.com/7067/6871108265_4f779c0303.jpg

http://farm8.staticflickr.com/7196/6871107363_bd01b2abe8.jpg

The decals are not 100% where they were before, but I think unless you had a picture next to it you'll never notice.

http://farm8.staticflickr.com/7177/6871110923_6370a1daec.jpg

http://farm8.staticflickr.com/7196/6871109063_16ab1875de.jpg

http://farm8.staticflickr.com/7066/6871109937_84fb5be8b2.jpg

Now to get back to the chassis!

Wow! That cabinet work looks fantastic...She'll a nice set when its all back together ::yes:

Nothing wrong with the way it looks! You are on the home stretch with that cabinet...

I'd like to tell a cautionary tale for any one reading this that wants to learn from other peoples mistakes, rather than make their own.
Rebuilding multi-stage electrolytic capacitors has been the most challenging thing I've done thus far on this restoration. As those of you know who have been following this thread from the beginning, I replaced all of the paper and electrolytic capacitors in this set before I applied power. Due to a misprint in the schematic I put a 160v capacitor where a 450v capacitor belonged. What I was greeted with was a cloud of capacitor smoke. Taking the schematic at it's word and thinking that I some how miswired the restuffed capacitor I rebuilt and hooked up the same valued capacitors outside of the set to have visual confirmation that my leads were ok. Again I was greeted with a pop and a cloud of foul smelling smoke. Slightly frustrated at this point I dived into the schematic, and the wiring of the set and deduced that the voltage rating of the cap was indeed the problem. At this point I had two things going against me, I was frustrated because I had two "failures" and I was cocky because I, a rookie, had "cracked the code" and figured out that the schematic was incorrect. I should have turned the lights out and came back another day, I didn't. What I did was hurry to rebuild the capacitors in question so that I could feel like progress was being made and I could shoot that nice raster picture to post here. The result was an incorrectly wired capacitor that was done in such a way that even when another cap was jumped across it's leads it wouldn't show itself. I can, however, take a positive away from this mistake, and that is what I have learned through the trouble shooting steps that the knowledgeable and helpful people here at VK led me through.
Learn from my mistake, when frustration or any other emotion that forces you to work anything less than 100% focused and deliberate, turn the lights out and come back another day.


Now for the good news. The set currently resembles a patient on life support as I have frankenwired some capacitors outside of the set to take the place of the multi-stage can in question.

http://farm8.staticflickr.com/7204/6883509037_a6dd7442bf.jpg

I have ordered smaller replacement capacitors for that section but for now I have a much better picture on screen :)

http://farm8.staticflickr.com/7052/6883510137_0197d10681.jpg

There is still much work to do, but for tonight I'll turn the lights out and come back another day.

you've been making cap upgrades which means you've been messing with the wiring, find the wiring fault and repair it.


:smoke:


Not tooting my own horn or anything, but I had a feeling that was the problem. Can't blame yourself though, I frequently find errors in schematics so it's not a very big leap to assume something was misprinted. Glad you found out what was causing the issue, pic looks great from what I can see. :thmbsp:

And, also at the risk of sounding "cocky", if you are replacing a multi-section capacitor, the values are usually written on the can so you can "double check" the schematic. Bet the error was in a Sams Photofact? They are usually good but can have mistakes. Glad you sorted it out...

Congrats, I'm glad you got it sorted out too :)

Good job of sleuthing it out, Mr. Dragonslayer. :banana: And you learned an important point too: Sams is notorious for misprints and diagram errors. The old adage "Trust but verify" always applies. I liken it to riding a bike on city streets. Assume every parked car door is going to swing out on you.

BTW, which cap was it?

Fired the set up for the first time and got a surprise. C128B (one of the main filter caps) blew up in a cloud of foul smelling smoke.
**THIS IS IMPORTANT TO ANY ONE WHO WILL READ THIS AND START A RESTORATION OF THEIR OWN**
The Rider schematic has a misprint. It incorrectly switches the placement of C128A and C128B.
http://farm8.staticflickr.com/7008/6778437323_1e2c9a5be7.jpg
Why is this important? Because C128B is rated at 150v not 450v and I'd like to save you the :mad: look your wife will give you when you smell up the house.
After replacing the offending capacitor I fired the set up again. No explosions :), however I didn't hear the horizontal oscillator so I investigated in that area. After swapping the 6SN7 out (it was one of the few non RCA branded NOS tubes) with another tube in the set I got the characteristic sound of the oscillator.
I took some voltage measurements and every thing was in the neighborhood so I installed the crt fired the set up and was greeted with.
http://farm8.staticflickr.com/7001/6779004645_bc8e8f6d7c.jpg
No video or sound just yet but it seems like a good time to quite for the evening.

I think the more important lesson to take is that I was frustrated and worked in a hurried manor that caused me to make a mistake. Learn from my bone headedness and when you get :gigglemad turn the lights off and return when you're :cool:.

I need to learn to re-read stuff. Doh.:o

Making some more progress on the set. I went though every resistor in the horizontal circuit and replaced quite a few that were way out of spec, or completely open. I fired the set up after each replacement to make sure nothing went wrong, and to enjoy seeing the picture get better and better with each step. I still have (at least) two problems with the video currently. One problem I could not get completely sorted out with resistor replacement in the horizontal circuit was a bit of tearing at the top of the screen.
http://farm8.staticflickr.com/7040/6904564813_7376780cea.jpg
It was easiest to photograph the phenomenon by injecting video right at the grid of the video amp and adjusting contrast until it showed up. It is possible to get a stable picture most of the time, but when there is full motion video on screen it will occasionally tear horizontally at the top of the screen, just like the picture above but some times much worse. The last set I worked on had a Sams for it and gave a procedure for horizontal adjustment. I cannot seem to find one in the Rider for this set however. Maybe it's just a matter of adjustment that I'm missing?
My other problem is before the video amp. I'm getting some trailing ghosting in the picture.
http://farm8.staticflickr.com/7208/6904566323_1298cb4b89.jpg
I haven't dived into this problem just as I would like to get the horizontal sorted first but thought I'd share.

In regards to those trailing ghosties, be sure and check peaking coils L105 and L106 for continuity.

Seems like the tearing/'flagging' is related more to signal overload than horiz. adjustment since it straightens up as you lower the contrast. This set doesn't appear to have any AGC (automatic gain control) at all. The contrast ('Picture') control adjusts the gain of the 2nd IF tube, requiring you to manually adjust it for varying signal strengths. Too strong a signal and the pic gets the bends. Just one of the charms of the old beasties, sorta like riding the gain on an old TRF radio.

In regards to those trailing ghosties, be sure and check peaking coils L105 and L106 for continuity.

Seems like the tearing/'flagging' is related more to signal overload than horiz. adjustment since it straightens up as you lower the contrast. This set doesn't appear to have any AGC (automatic gain control) at all. The contrast ('Picture') control adjusts the gain of the 2nd IF tube, requiring you to manually adjust it for varying signal strengths. Too strong a signal and the pic gets the bends. Just one of the charms of the old beasties, sorta like riding the gain on an old TRF radio.

L105 and L106 read a bit low on my voltohmist but they are in the neighborhood.
I've shot a couple of videos of what the set is doing. The first one is from the B&K 1077 and shows that the two problems seem to be interrelated. When I adjust the picture control I can get a steady picture with ghosting, or a ghost free picture with tearing, but not both. The ghosting is much easier to see in the black blocks at the bottom of the screen (is there a proper name for those blocks?).
http://www.youtube.com/watch?v=rLJRdzFB-yU
The other video displays the occasional horizontal tearing towards the top of the screen with full video that I described before.
http://www.youtube.com/watch?v=28X9hkIWCQE
I'll check the resistors and voltages in the video and if stages next to see if anything jumps out there.

The tearing seems to be from overloading, the ghosting possibly some misalignment in the i.f.'s?

Whaddabout the case ? I have a VERY GOOD furniture refinisher here...I've used them quite a lot & they understand about tube diagrams, decals, etc.. Just sayin. PM me for their addy/phone #

The 'ghosting' doesn't look like the smearing/ringing of fine detail you typically see with IF misalignment.
What happens if you inject video at the CRT grid, working back point by point? Have to reduce the B&K's output as you move back (to keep the pic from flagging) and reverse the phase a time or two. See at what point the ghosting appears.

Whaddabout the case ? I have a VERY GOOD furniture refinisher here...I've used them quite a lot & they understand about tube diagrams, decals, etc.. Just sayin. PM me for their addy/phone #

Sorry that there's not much to report on the cabinet. Since I'm not doing the work myself I can't post regular reports with pictures. The only piece of news I have is that the day after I applied the decals to the set my refinished sprayed a coat of lacquer to seal them in. He just underwent hand surgery on both hands so he's working slowly. He knows how picky I am and is doing some other less intricate projects while he heals up. :) all the more time to perfect the chassis.

Regarding the tearing, I don't know what the horizontal setup procedure is for this set but it might be due to instability?

Much to report to all of you. First off I replaced my temporary modern Radio Shack resistors with some beautiful old carbon resistors. "Out With The New, In With The Old!" That's all kind of boring and just those things you do when you want an original look at the end of the restoration. On another note I have finally got off my :butt1: and got an oscilloscope for the bench. I put the scope into service right off the bat testing a theory. If you remember I had two problems, ghosting in the image and some horizontal tearing towards the top of the screen. I had previously noticed that the two were mutually exclusive as I adjusted the picture control. After thinking about it overnight I thought that maybe the ghosting problem was me over-driving of the signal (as old_coot88 explained before " The contrast ('Picture') control adjusts the gain of the 2nd IF tube"). I used the RF Attenuation control on my B&K to achieve the same results as adjusting the picture control on the set. What I got was horizontal tearing at the low end of the signal and as the gain was cranked up the tearing disappeared but the ghosting appeared. What I theorized was that the horizontal sync pulses were being attenuated at a normal signal level forcing me to overdrive the signal to bring it back thereby inducing ghosting.
How nice it is to have a scope to test this theory.
Here is the set with the signal cranked and without any horizontal tearing.
http://farm8.staticflickr.com/7063/6912982721_b9894edbc9.jpg
Here are the sync pulses.
http://farm8.staticflickr.com/7184/6912979181_0383f52bcb.jpg
Here is the set at what I think would be a normal signal level (half way up the dial on the B&K 1077, which looks to be about the same level coming off my rf modulator on my DVD player). This is the level at which I get horizontal tearing.
http://farm8.staticflickr.com/7048/6912981615_111dd12ee5.jpg
And here are the sync pulses.
http://farm8.staticflickr.com/7194/6912980581_d5ed53a367.jpg
It seems to me that I have a sync problem. Am I off base?
I haven't looked into possible causes of the problem, I'll leave that one for tomorrow.

I picked up the cabinet from my finisher today and thought I'd share some eye candy. I have no photography experience so it was very hard to show how this cabinet really looks in person but I've picked the best shots out of the many that I took.
http://farm8.staticflickr.com/7206/6780700950_72f067667e.jpg

http://farm8.staticflickr.com/7209/6780708394_77595f1a80.jpg

http://farm8.staticflickr.com/7194/6780707440_df58cb3260.jpg

http://farm8.staticflickr.com/7205/6780709406_e53fe5f59b.jpg

http://farm8.staticflickr.com/7202/6926818303_05d65e2721.jpg

http://farm8.staticflickr.com/7070/6780699030_d3144a9832.jpg

I'm very happy with the way the cabinet turned out.

I picked up the cabinet from my finisher today ...

I'm very happy with the way the cabinet turned out.

I would guess that you are very happy. It sure looks very nice. Glad that you have it back and we await the finished product...

That looks very nice!!

Aww, man....I'm in LOVE....BTW, Ahh HATE Yew ! (grin) -Y. Sam, Esq.

Hey that is a great refinishing job cannot wait to see the finished set entirelypost the pix as soon as you can...Timothy

Wow, that sure is beautiful!

I did not know one could turn wood into gem stone. :D

After much measuring, tweaking, checking, rechecking, etc.. I'm quite stuck on what my horizontal sync problem is :saywhat:. I've checked and rechecked the resistors in the sync and horizontal sections and everything checks ok. I've taken voltage measurements in those areas and they check reasonably close as well. I've also swapped the 6SN7GT's (all of which are checked good on a tube tester) around the set and out of the sync/horizontal oscillator sections. I just can't seem to nail where the problem is coming from.
My best stab at the answer is the output of me sync amplifier is really noisy. This is only my best guess, could some one could confirm or steer me in a different direction? The waveform is from the output of the sync amp.

http://farm8.staticflickr.com/7051/6929755511_74d71737aa.jpg

This is the reference from Rider's.

http://farm8.staticflickr.com/7208/6783615450_d8af44481d.jpg

Does the picture have the same problems if you connect a different signal source (DVD player, whatever)?

Phil Nelson

Yes, the problem is the same with full video via a modulated DVD player.

You've probably already checked 'em, but there's two more peaking coils, L103 and L104 that you might want to doublecheck for continuity.
If those are good, what happens if you inject video from the B&K at the CRT grid, working back point by point towards the 6H6 detector diode? Need to reduce the output as you move back (to keep the pic from tearing/flagging) and reverse the phase a couple of times (since a tube's plate is always opposite phase from the grid). Also watch for the point at which the 'trailing ghosties' appear (that's assuming they arise after the detector in the video chain).

You've probably already checked 'em, but there's two more peaking coils, L103 and L104 that you might want to doublecheck for continuity.
If those are good, what happens if you inject video from the B&K at the CRT grid, working back point by point towards the 6H6 detector diode? Need to reduce the output as you move back (to keep the pic from tearing/flagging) and reverse the phase a couple of times (since a tube's plate is always opposite phase from the grid). Also watch for the point at which the 'trailing ghosties' appear (that's assuming they arise after the detector in the video chain).

L103 and L104 read on spec. It appears that the ghosting is upstream from the 6H6 in the IF or RF stages, however I am thinking that the ghosting is due to an over-driving of the signal and not a receiver flaw. After some additional tweaking, and more importantly correcting the height of the picture, the horizontal instability, while still there, is less severe than before. adjusting the set without a reference for height tripped me up on the last (round screen) set that I worked on.
I made a template of the crt mask out of card stock to place in front of the screen to get a better idea of what I need to adjust to. I took a video of the set with full video to give an idea of how it looks at this point. The dark diagonal line in the video is not actually on the set, just the video.
http://www.youtube.com/watch?v=PTXslUBXsyE
The modulator that I'm using is not the best, I hope to replace it soon with a BT modulator just as soon as I find one in my price range. I think my plan of attack on the set is to do a full audio and video alignment according to the procedure outlined in the Rider's schematic. The audio is so bad that there is no sound output currently except some higher frequency FM stations at the low side of the channel selector. I would be doing the alignment under the expert tutelage of a local antique electronic repair expert who has been doing this for decades, and has the necessary equipment for the task. After the set is aligned I can revisit the horizontal instability if need be.

Hey that's great that you've got an 'Elmer' handy to mentor you through a full sweep alignment and show you first-hand the whys and wherefores of the procedure. Actually the video IF alignment looks pretty spot-on. You might ask him to detune the IFs a bit so you can see the ringing/smearing of fine detail that occurs from misalignment.
Barada nikto, K'laatu
:lazer:

Much progress today. The aligment went very well and taught me much. The picture, sound, and rf oscilator all needed to be adjusted. The one adjustment that gave the most trouble was the rf oscilator on channels 3 and 4. I also had some trouble with the yoke and ion trap placement to get maximum brightness and a full raster. I had to tweak both the yoke and ion trap extensively to achieve the brightest possible full raster picture. All that being said, the set is back together and looking really good.
Here is a couple pictures of the bottom of the chassis.

http://farm8.staticflickr.com/7189/6950721433_60091f14ca.jpg

http://farm8.staticflickr.com/7199/6804611098_54c0b305e7.jpg

A couple of pictures of the screen with a test pattern. Notice the slight shadow in the lower left hand cornet of the screen.

http://farm8.staticflickr.com/7180/6950727243_9d250ba4e1.jpg

http://farm8.staticflickr.com/7051/6950729551_14f0e14b38.jpg

One more shot.

http://farm8.staticflickr.com/7193/6950728345_8ca60d7c47.jpg

Stick a fork in it. Its DONE. EXCELLENT job ! Don't "F!ck" w/it anymore, you're liable to Screw Somethin' Up...(grin) (Redneck Engineerin' 101-Know when to leave Well Enough Alone...)

Horizontal linearity is slightly off, see how the right side of the picture is slightly 'longer'? You should see if you can get the linearity fixed up and fix that shadow (which is likely neck shadow), then the picture will be very good indeed. Your cabinet looks pristine, I'd be happy to own a set that pretty. :thmbsp:

Horizontal linearity is slightly off, see how the right side of the picture is slightly 'longer'? You should see if you can get the linearity fixed up and fix that shadow (which is likely neck shadow), then the picture will be very good indeed. Your cabinet looks pristine, I'd be happy to own a set that pretty. :thmbsp:

I'm going to take a second stab at the shadow problem again at some point. Is there any thing else that I can adjust besides the ion trap and the yoke? It took me an hour of adjusting to get a reasonably bright picture and the almost full raster that you see. When I adjusted the ion trap to maximum brightness the raster was severely cut off at the bottom, and when I adjusted the ion trap for a full raster the pictures was severely dim.
I'll also give a tweak to the horizontal linearity to see if I can't get it a little closer to perfect.

And another notch in his solderin' gun for The Dragonslayer. :D
Gauging by that crosshatch pattern, i would be happy as heck with the H.linearity as it is.
Re. the neck shadow, the yoke is slid fully up against the bell is it not? Might try flipping the ion trap end-for-end an rotating some more (if you haven't already).

And another notch in his solderin' gun for The Dragonslayer. :D
Gauging by that crosshatch pattern, i would be happy as heck with the H.linearity as it is.
Re. the neck shadow, the yoke is slid fully up against the bell is it not? Might try flipping the ion trap end-for-end an rotating some more (if you haven't already).

The yoke is fully up the neck of the crt resting at the bell, but it seems like it needs to be slid up a bit more (which is impossible). I'll get back at it soon and do some more adjusting, it's nice to just enjoy the set for now.
I've got a video of the set up and working, it's not my greatest work. The audio is pretty low and the shot could have been closer. As soon as I get my new BT modulator this week I'll shoot a better one and post it.
http://www.youtube.com/watch?v=f4TsUR4WS6o

Sometimes there are two ares on the CRT neck where the ion-trap magnet will work. Use the one closer to the base. Also, you could try slipping it of the neck and flipping it around.