I am replacing an arched out HV rectifier socket in my Zenith 5111. The rectifier is a 3AT2. The 1.5K Ohm resistor that once resided there across pins 5 and 9 was burned in two. A very kind gentleman and member pulled a socket assembly for me from a chassis 1 year newer in which no resistor was used. This could be from a prior repair or by a change in design.

In another thread I have questioned what this series resistor actually is doing in the circuit, but with that not being the primary topic I never found out. Someone with a lot of experience in TV repair from that period said that this resistor was known to burn up and that techs often simply jumped over it. I am thinking that it may be a bleeder resistor, but it's only speculation. That would at least explain it not being essential in the circuit for operation.

I have a 1.2K Ohm 2W on the way. Easy enough to pop in just for safety and security. However, the jumper is already in place in the part coming and I am going to be working in very cramped space. So if anyone has any specific information as to the need or lack thereof as well as function of this resistor, it would be greatly appreciated. I may even need to find the correct 1.5K if it were to be a matter of critical voltages or current being spot on, but so far the information given to me speaks that this will not be an issue.

Thanks

Tube

I found HV service tips covering early Zenith color TVs in Tab Books No. 502 by R.L. Goodman, Zenith Color TV Service Manual chapter 5 page 68. It says:

"In all chassis using the 3AT2 HV rectifier, the picture may have all sorts of vertical, horizontal, and diagonal lines across the screen, plus elaborate rainbow effects. Also, there may be a loss of color, even though RF interference is not evident in the picture.
The cause, in this case, is an isolation resistor, located under the HV rectifier socket that has burnt or deteriorated. This is caused by a shorted HV rectifier. The most effective solution is to eliminate the resistor completely. Solder a wire across the socket terminals where the resistor was wired in, and replace the 3AT2 HV rectifier."

" ... check the filter resistor under the HV rectifier socket for arcing. DO NOT replace the resistor. Solder a lead-wire between the socket terminals where the resistor was removed."

"Improved High Voltage Rectifiers
(X and N Series Chassis)
Improvements in 3AT2 high-voltage rectifier tubes has eliminated the possibility of vertical streaking known as diodehausen. Thus, the 1.5K resistor in series with the high-voltage anode lead is not needed and has been replaced with a jumper wire to keep the outer shell of the 3AT2 socket at high-voltage potential."

I bought my used copy on Amazon. It covers from chassis 27KC20 through 14Z8C50, which includes the 25MC30 chassis.

Dave

Dang, I was gonna suggest jumpering that resistor out, but thought the better of it, figuring there must be some arcane reason for its being there.

Wow! This information is absolutely amazing and thanks so much Dave! If my fly is not somehow damaged I am thinking that the socket replacement that I am about to do is not only going to take away the raster distortion, but also may give me 'for sure' color as that has been intermittent through all of this. I haven't talked about it so as not to throw too much out there and confuse the main issues.

VK once again and as always has been an invaluable tool in this matter! Really, it's the members, which are some of the best people that I can imagine gathered to one place.

I should have my socket in a few days and with a little luck may have one nice playing Zenith! I will keep everyone posted if for no other reason there are more Zenith people starting to come out from behind all of the CTC repairs. Not bashing RCA folks; they just need more repair data for more repair. With Zenith the quality really did go in before the name went on!

... With Zenith the quality really did go in before the name went on!
All 'cept for their plastic efficiency coil forms.:D

Wow! This information is absolutely amazing and thanks so much Dave! If my fly is not somehow damaged I am thinking that the socket replacement that I am about to do is not only going to take away the raster distortion, but also may give me 'for sure' color as that has been intermittent through all of this. I haven't talked about it so as not to throw too much out there and confuse the main issues.

VK once again and as always has been an invaluable tool in this matter! Really, it's the members, which are some of the best people that I can imagine gathered to one place.

I should have my socket in a few days and with a little luck may have one nice playing Zenith! I will keep everyone posted if for no other reason there are more Zenith people starting to come out from behind all of the CTC repairs. Not bashing RCA folks; they just need more repair data for more repair. With Zenith the quality really did go in before the name went on!

You are quite welcome, glad to help. Hope it fixes your color issue.
Dave

I will keep everyone posted if for no other reason there are more Zenith people starting to come out from behind all of the CTC repairs. Not bashing RCA folks; they just need more repair data for more repair. With Zenith the quality really did go in before the name went on!

The best part about fixing a "golden age" Zenith is that the service manuals pretty much cover every damned failure possibility, due to the fact that on the rare occasion something did go wrong, it usually involved one of the voodoo component bits. Detail is everything in terms of maximizing your revenue per lineal service-bench foot. Short occupancy is good, hangers-on for head-scratching and goose-chasing are bad. :thmbsp: When your unfamiliar symptoms are described spot-on in the book it makes you just want to hug the engineers.

DO NOT replace the resistor. Solder a lead-wire between the socket terminals where the resistor was removed."

, the 1.5K resistor in series with the high-voltage anode lead is not needed and has been replaced with a jumper wire to keep the outer shell of the 3AT2 socket at high-voltage potential."



Dave

I guess I will go ahead and jump over what was going to be a new resistor. Although not needed for the set's operation, I was thinking that at least it was providing a short circuit protection of sorts as they go open due to shorted rectifiers. When way more experienced techs say "DO NOT", I listen!:thmbsp:

Thanks again!

I just replaced 1.5k resistor on my 25LC20 (before reading this) old one looked all right but measured low (1.26k). Low resistance is also a sign of heat stress/damage. Maybe it's there to protect rectifier and or Pic tube or people from 22kv!

The HV rect filament wire was hardened from heat and had 1/2" bare stripped connections to socket! Who did that? Not factory?

There was a lot of wax melted from flyback!

The 2,2k final Horiz Output screen resistor looked cooked - was very high 11k! but set worked.

Will soon see if this corrects my vertical lines (is this "diodehausen"? screen picture (http://videokarma.org/attachment.php?attachmentid=185633&d=1422826249))

I guess I will go ahead and jump over what was going to be a new resistor. Although not needed for the set's operation, I was thinking that at least it was providing a short circuit protection of sorts as they go open due to shorted rectifiers. When way more experienced techs say "DO NOT", I listen!:thmbsp:

Thanks again!

Here is a picture of the Goodman manual page on the 3AT2 and HV resistor issue. Also here are the two pages of 25MC30 service notes.

Dave

I just replaced 1.5k resistor on my 25LC20 (before reading this) old one looked all right but measured low (1.26k). Low resistance is also a sign of heat stress/damage. Maybe it's there to protect rectifier and or Pic tube or people from 22kv!

The HV rect filament wire was hardened from heat and had 1/2" bare stripped connections to socket! Who did that? Not factory?

There was a lot of wax melted from flyback!

The 2,2k final Horiz Output screen resistor looked cooked - was very high 11k! but set worked.

Will soon see if this corrects my vertical lines (is this "diodehausen"? screen picture (http://videokarma.org/attachment.php?attachmentid=185633&d=1422826249))

I am guessing that diodehausen must be an effect similar to barkhausen resulting in vertical lines. You might want to try the Goodman suggestions posted above. They mention a newer version of the 3AT2 solving the problem.

Have you checked the HO cathode current? You mention 22KV, shouldn't that be 25KV? A lower HV setting on my 29JC20 causes the cathode current to rise.

Dave

Does the Goodman manual say anything about vert foldover?

I left the new 1.5k (2w) resistor in as it was reassembled.

Still have my H-synced artifact on screen which can be heard in speaker also, seems to be a micro arcing in some component getting into the RF then onto screen - more pronounced as you fine tune into chroma/sound

Does the Goodman manual say anything about vert foldover?

I left the new 1.5k (2w) resistor in as it was reassembled.

Still have my H-synced artifact on screen which can be heard in speaker also, seems to be a micro arcing in some component getting into the RF then onto screen - more pronounced as you fine tune into chroma/sound

I'm the guy who's guilty of replacing the resistor on the socket I sent to tubejunke. I wanted to get it in the mail in a timely manner. I only had a 1.2K 2W res on hand. The socket I got had a jumper.
I recall, that I inquired about the resistor at the Zenith distributor. The head technician said, just to jumper it out. It's not needed anymore. That has to be 40+ years ago, before I bought the Goodman book.

I just replaced 1.5k resistor on my 25LC20 (before reading this) old one looked all right but measured low (1.26k). Low resistance is also a sign of heat stress/damage. Maybe it's there to protect rectifier and or Pic tube or people from 22kv!

The HV rect filament wire was hardened from heat and had 1/2" bare stripped connections to socket! Who did that? Not factory?

There was a lot of wax melted from flyback!

The 2,2k final Horiz Output screen resistor looked cooked - was very high 11k! but set worked.

Will soon see if this corrects my vertical lines (is this "diodehausen"? screen picture (http://videokarma.org/attachment.php?attachmentid=185633&d=1422826249))
Regarding the HV rect filament wire, that wire is resistance wire and probably gets warm in operation. The insulation probably receeded from the heat. That I've seen before. :scratch2:

The filament loop wire is not resistance wire.
What manner of engineer would want to squander hard won deflection power as waste heat? :saywhat:

The hardened insulation is probably from ozone.

Does the Goodman manual say anything about vert foldover?

I left the new 1.5k (2w) resistor in as it was reassembled.

Still have my H-synced artifact on screen which can be heard in speaker also, seems to be a micro arcing in some component getting into the RF then onto screen - more pronounced as you fine tune into chroma/sound

Here are the Goodman service tips that include the 25LC20. The fifth page describes an arcing issue. I will send the last page of this in another post.

Dave

Last page.

The filament loop wire is not resistance wire.
What manner of engineer would want to squander hard won deflection power as waste heat? :saywhat:

The hardened insulation is probably from ozone.

Probably the same engineer that specified the 1.5K resistor, in series with the CRT second anode.
According to Sams, it's stated as resistance wire. It's a small guage solid wire, instead of stranded wire, like used on practically all the flybacks, that I ever replaced.
I don't know, how much voltage drop is required, as Sams doesn't specify a resistance value. :scratch2:

Probably the same engineer that specified the 1.5K resistor, in series with the CRT second anode.
According to Sams, it's stated as resistance wire. It's a small guage solid wire, instead of stranded wire, like used on practically all the flybacks, that I ever replaced.
I don't know, how much voltage drop is required, as Sams doesn't specify a resistance value. :scratch2:
Dang. Learn somethin' new every day. Be interesting to know more background theory on da resistance wire thing. Maybe to de-stress the 3AT2 and exclusive to Zenith (?)
All the HV rect filamant loops I ever replaced were standard anode wire. Occasionally there was one (usually B&W) that had a small resistor of a few ohms in series with the fil. This was always in other brands than Zenith.

Thanks everyone, and special thanks to Dave with the pages posted. This turned out to be a great thread that I think will be an excellent source in the future for others. I think I am far from the first to be hunting a corona or arching issue which just can't be seen; even in the dark.

As I have said before; I don't know if I would ever have found this if the damage from the arching hadn't burned my rectifier socket causing a pin to pull with the tube and leading me into further investigation.

Does the Goodman manual say anything about vert foldover?

I left the new 1.5k (2w) resistor in as it was reassembled.

Still have my H-synced artifact on screen which can be heard in speaker also, seems to be a micro arcing in some component getting into the RF then onto screen - more pronounced as you fine tune into chroma/sound

The Zenith 29JC20 service manual says:

"The most common cause of vertical fold-over is failure of the vertical oscillator output tube. Vertical output grid coupling capacitor being shorted or leaky can cause improper operation of the vertical output tube, causing vertical fold-over."

So maybe replace the grid cap and try some other vertical output tubes?

Dave

Thanks everyone, and special thanks to Dave with the pages posted. This turned out to be a great thread that I think will be an excellent source in the future for others. I think I am far from the first to be hunting a corona or arching issue which just can't be seen; even in the dark.

As I have said before; I don't know if I would ever have found this if the damage from the arching hadn't burned my rectifier socket causing a pin to pull with the tube and leading me into further investigation.

Hope the information helps. Its just guesses until you try it and find the cause. Please let us know how it turns out.

Dave

Here are the Goodman service tips that include the 25LC20. The fifth page describes an arcing issue. I will send the last page of this in another post.

Dave

Thanks for extra pages and tips! Lot to try here.

Hope the information helps. Its just guesses until you try it and find the cause. Please let us know how it turns out.

Dave

I am certain now of exactly what to do as far as proceeding with the repair of the burned socket which was without question. In my search for a replacement socket I was finding that some sets had the resistor and others (newer) didn't. I needed more information as my inclination was not to eliminate or alter something that was at least in my set. Now I can proceed with certainty and the information given is beyond helpful.

I still can't help but wonder how I had HV with the resistor burned in two. My only guess is that it was arching across the two burned open ends of the resistor. The burned out socket (pins 4 and 5) as well as same tube pins badly corroded may be further evidence backing this theory. Heck, pin 4 is a blank! Beyond a shadow of a doubt the resistor didn't burn any of the last number of times the set was in use.

Beyond the resistor topic my immediate concern will be that of HO cathode current being high at line potential. I doubt that this repair will correct that, but all of this is a learning process for me. Perhaps the issues mentioned and soon to be corrected do play a hand in that. I will know as soon as the socket arrives (hopefully later today). Lots of snow here for this part of the country which makes for a perfect day to work on electronics projects.

my immediate concern will be that of HO cathode current being high at line potential. .

I'm worried about that also given the melted wax on my 25LC . Perhaps a small cathode resistor could be added to Horiz Out and its voltage drop could be used as tuning indicator to optimize the Horiz Efficiency Coil? It would also reduce H.O.T. primary current.

I see the 25LC schematic AC input is designated 120v - within spec of modern utility voltage.

Was looking for "troublesome" degaussing thermistor and found the 25LC20's have no automatic degaussing coil:worried:

This may sound ridiculous, but I have to ask if anyone can verify some 3AT2 pin outs for me. Simply what I need to know is whether the jumper replacing the 1.5K resistor joins at pin #4, or pin #5 along with the crt second anode lead.

As I have said, my sockets connectors 4 and 5 both fell out, but when I first pulled the tube and discovered this I thought that #4 came out with the tube and had nothing soldered to it. The new socket has the resistor and anode lead at pin #4 which again is a blank pin. I am probably just mistaken about which connector came out with the tube. The blank pin is probably just used as a junction for the "series" resistor. If it went to #5 then it looks like both ends of the resistor or jumper would be across or shunted to the cathode by looking through the glass. I just want to wire this up right the first time and need to be sure. The schematic only shows the heater connections and plate cap. Thanks!

The 25MC30 schematic shows the 1.5K resistor connects to pin 1 and 9 of the 3AT2. The 3AT2 PDF shows that pin 4 is a no connect. So pin 4 could be used as a tie point for connecting the other end of the resistor to the anode lead. The schematic does not show this, so I'm guessing.

Dave

3AT2 PDF:
http://frank.pocnet.net/sheets/049/3/3AT2.pdf

OK, I just figured out that I have been using Sams Set 722, Folder 4 which is for the 25LC30/U! Geez! It only specifies pins 1 &12 as heater connections. Mistake #1! Either way, like you I am assuming that the NC #4 is indeed a tie point as #5 certainly would not be right. I need to get a .pdf on my 25MC30 somewhere. However, it shows pins 1 and 9 according to what you are seeing and that would still have the resistor shunted to the cathode as the.pdf states, "pin 5 same as pin 1."

I hope I am correct in thinking like you that only one end of the resistor would be at the cathode, or pin 9 and the rest simply goes to second anode at CRT.

OK, I just figured out that I have been using Sams Set 722, Folder 4 which is for the 25LC30/U! Geez! It only specifies pins 1 &12 as heater connections. Mistake #1! Either way, like you I am assuming that the NC #4 is indeed a tie point as #5 certainly would not be right. I need to get a .pdf on my 25MC30 somewhere. However, it shows pins 1 and 9 according to what you are seeing and that would still have the resistor shunted to the cathode as the.pdf states, "pin 5 same as pin 1."

I hope I am correct in thinking like you that only one end of the resistor would be at the cathode, or pin 9 and the rest simply goes to second anode at CRT.

I probably have a paper copy of the factory schematic, and possibly have the whole Zenith manual too. If you want I could check if I have it, and scan it for you if I do.

Dang. Learn somethin' new every day. Be interesting to know more background theory on da resistance wire thing. Maybe to de-stress the 3AT2 and exclusive to Zenith (?)
All the HV rect filamant loops I ever replaced were standard anode wire. Occasionally there was one (usually B&W) that had a small resistor of a few ohms in series with the fil. This was always in other brands than Zenith.

Sams does specify 1.8ohms as the resistance of the wire. Didn't see that before. :scratch2:

OK, I just figured out that I have been using Sams Set 722, Folder 4 which is for the 25LC30/U! Geez! It only specifies pins 1 &12 as heater connections. Mistake #1! Either way, like you I am assuming that the NC #4 is indeed a tie point as #5 certainly would not be right. I need to get a .pdf on my 25MC30 somewhere. However, it shows pins 1 and 9 according to what you are seeing and that would still have the resistor shunted to the cathode as the.pdf states, "pin 5 same as pin 1."

I hope I am correct in thinking like you that only one end of the resistor would be at the cathode, or pin 9 and the rest simply goes to second anode at CRT.

The way I found the socket, the filament went to pins 9 and 12. The regulator plate lead went to pin 9 and jumper went from 9 to 4. The 2nd anode lead went to pin 4, as well as the jumper going to the metal cup.
I, like a fool, removed the jumper and installed the resistor. It looked like the jumper was installed by a tech. Didn't look like factory issue.
Just remove the resistor, install the jumper and wire, per these instructions.

The way I found the socket, the filament went to pins 9 and 12. The regulator plate lead went to pin 9 and jumper went from 9 to 4. The 2nd anode lead went to pin 4, as well as the jumper going to the metal cup.
I, like a fool, removed the jumper and installed the resistor. It looked like the jumper was installed by a tech. Didn't look like factory issue.
Just remove the resistor, install the jumper and wire, per these instructions.

OK, so my thinking was right about it not making sense to connect both ends of the resistor or jumper to internal cathode connections. #4 being an NC (no connection) will just be a tie in as someone else has mentioned. I was just mixed up between 4 and 5 which in my socket are both pulled out and there is just a hole there. Anyway, I will give it a try hopefully this weekend.

Thanks!

[QUOTE=Zenith6S321;3126651]The 25MC30 schematic shows the 1.5K resistor connects to pin 1 and 9 of the 3AT2. The 3AT2 PDF shows that pin 4 is a no connect. So pin 4 could be used as a tie point for connecting the other end of the resistor to the anode lead. The schematic does not show this, so I'm guessing.

Dave

Hi Dave, is there any way that you can post something showing this resistor connected to pins 1 and 9. Reason being is that if it shows it there then both ends are interconnected to the cathode. According to the .pdf on the tube, pins 2, 5, 6, & 9 are the same as pin 1. Now the second anode lead does for sure connect to one end of the resistor, but I dare to ask is it at a no connect as a tie point or is it at 1 and 9. There is a big difference that presents obvious concerns. My lack of completely understanding the circuit may lend to this.

Sorry to keep going back to this, but what I am reading surely makes me wish that I could see a for sure Zenith reference to this.

[QUOTE=Zenith6S321;3126651]The 25MC30 schematic shows the 1.5K resistor connects to pin 1 and 9 of the 3AT2. The 3AT2 PDF shows that pin 4 is a no connect. So pin 4 could be used as a tie point for connecting the other end of the resistor to the anode lead. The schematic does not show this, so I'm guessing.

Dave

Hi Dave, is there any way that you can post something showing this resistor connected to pins 1 and 9. Reason being is that if it shows it there then both ends are interconnected to the cathode. According to the .pdf on the tube, pins 2, 5, 6, & 9 are the same as pin 1. Now the second anode lead does for sure connect to one end of the resistor, but I dare to ask is it at a no connect as a tie point or is it at 1 and 9. There is a big difference that presents obvious concerns. My lack of completely understanding the circuit may lend to this.

Sorry to keep going back to this, but what I am reading surely makes me wish that I could see a for sure Zenith reference to this.

Here is a picture of the HV area of the Goodman 25MC30 schematic. It does show pins 1 and 9 together going to one end of the resistor. The other end of the resistor could go to pin 4(NC) to anchor the anode lead. Looking at the 3AT2 pdf I thinks that's ok as pins 2 and 9 are the cathode so they are at the same potential and already internally connected to pin 1 (one end of the heater). The other end of the heater is pin 12 which the schematic shows going to through the 2.35 ohm resistance wire to the flyback heater winding. Goodman does credit Zenith with a good portion of the illustrations in his service manual but he does not specifically say that the schematics are from Zenith. Did you take any pictures of the socket before you disassembled as a cross-check of the schematics?

Dave

OK thanks! This diagram drives home the fact that everyone was right but me. I just wanted to see it in black and white as my Sams's schematic only shows the heater connection. Your schematic clearly shows the corona ring being bonded to pin 1 which is the same as pin 9 where that connection is made on mine with one end of the resistor and the plate cap of the regulator. Makes no difference. So the other end along with the second anode lead are at pin 4 of NC just as we all suspected and as DieselJeep has it.

I didn't get a picture because the initial connector pulled out with the tube clean of solder and somehow I had it stuck in my head that it was on pin 4. Duhhh! GeeZ! When I pulled the assembly apart the split resistor, connector and anode lead fell to the bottom of the cage leaving me with two adjacent open holes. In the name of not looking like a complete idiot; at least I suspected that what I had in mind would have caused some major issues and all of this might have been for nothing.

Thanks once again for advice and more helpful information. My 25LC30/U is not going to serve me well in this. I didn't realize that Zenith had that many design changes in only a few years. The set pictured on my folder looks like my set. Maybe next time I will have good news.

I thought I could get the HV cage off without removing or pulling back the chassis as I got all but one screw out. That one screw is mid way deep and close to the cabinet. Can't win em' all, but removal of the cage will make the job much easier than trying to work through the cover.

Is HV actually set to 25kv on these? What is the procedure for setting the efficiency coil?

Is HV actually set to 25kv on these? What is the procedure for setting the efficiency coil?

25Kv is generally where most people seem to set them and many manufacturers recommended. The efficiency coil is used to set the cathode current of the horizontal output tube. You have to place a meter in series with the grounded cathode of the tube. There are a few opinions on the ins and outs of how the meter is set up, but I simply broke the cathode to ground connection and ran two leads out so I could check this current anytime I want. Some people believe in placing a capacitor across the two leads to protect the meter. You may want to look into that, but I didn't worry with it and had good results.

Other than that you operate the set normally and turn the slug slowly and find what is called the "dip" point or the point where the lowest current flows and that's about it. If you are like me, you won't be satisfied with that current as it may still be too high due to some other component causing that condition. I hope this helps. I think you can Google setting the cathode current on a vintage color television" and there is a pretty in depth article on this topic, but it is a bit scattered in nature. If you find it you will see what I mean.

25Kv is generally where most people seem to set them and many manufacturers recommended. The efficiency coil is used to set the cathode current of the horizontal output tube. You have to place a meter in series with the grounded cathode of the tube. There are a few opinions on the ins and outs of how the meter is set up, but I simply broke the cathode to ground connection and ran two leads out so I could check this current anytime I want. Some people believe in placing a capacitor across the two leads to protect the meter. You may want to look into that, but I didn't worry with it and had good results.

Other than that you operate the set normally and turn the slug slowly and find what is called the "dip" point or the point where the lowest current flows and that's about it. If you are like me, you won't be satisfied with that current as it may still be too high due to some other component causing that condition. I hope this helps. I think you can Google setting the cathode current on a vintage color television" and there is a pretty in depth article on this topic, but it is a bit scattered in nature. If you find it you will see what I mean.

You will not get an accurate current reading without that capacitor. The inductance of the meter will change the tuning of the output circuit, and you will get inaccurate readings.

Try it again with a .47uF cap (any voltage >10 should work). You should get different readings, and they may be lower....

Remember the goal of measuring equipment is to load or disturb the behavior of the circuit under test as little as possible. The meter will have very low DC resistance, but may have higher AC impedance, the cap neutralizes that impedance by giving AC an alternate path to follow.

My 25LC30/U is not going to serve me well in this. I didn't realize that Zenith had that many design changes in only a few years.

Here are pictures of the whole schematic, if that helps.

Dave

Thanks Dave! That should help a lot.

Anyway, today I got everything reassembled and powered it up. Nothing bad happened, but nothing good either. No HV and only a blue glow in the top portion of the rectifier. I put it on my B&K tester and it is dead as a doornail like the heater is open.

Not sure where or why that would have happened. So, now I will hunt another 3AT2. A local supplier here has International Servicemaster brand which I don't want to get. If anyone has a supply of these and needs anything of that style base; I have a box of these type tubes which I have no use for including some pretty expensive sweep tubes. Just throwing it out there.

Anyway, today I got everything reassembled and powered it up. Nothing bad happened, but nothing good either. No HV and only a blue glow in the top portion of the rectifier. I put it on my B&K tester and it is dead as a doornail like the heater is open.

Not sure where or why that would have happened. So, now I will hunt another 3AT2. A local supplier here has International Servicemaster brand which I don't want to get. If anyone has a supply of these and needs anything of that style base; I have a box of these type tubes which I have no use for including some pretty expensive sweep tubes. Just throwing it out there.

Two birds with the same stone on this one? :beatnik:

http://www.ebay.com/itm/NOS-Zenith-S-3AT2-Electronic-Tube-FAST-FREE-SHIPPING-/141032045872?_trksid=p2054897.l4275


Zenith branded for true authenticity, and you no longer need to worry about heater juice. Sounds like a good deal to me. :yes:



(No affiliation with seller.)

Have you ever tried a solid state replacement? My only experience is watching a video by one of our members on YouTube where he tries one and the set absolutely would not operate correctly with that type rectifier in it. He went back to the vacuum tube and all was fine.

I just suspect that the arching that went on in more than one place with my old socket got the best of the tube. Months ago before any of the socket issues developed I put and International Servicemaster in the set and it only lasted a few minutes. The one that I just pulled out and tested bad was used before that and up until the socket issue of late. Hopefully another decent quality tube will take care of things.

Have you ever tried a solid state replacement? My only experience is watching a video by one of our members on YouTube where he tries one and the set absolutely would not operate correctly with that type rectifier in it. He went back to the vacuum tube and all was fine.

I just suspect that the arching that went on in more than one place with my old socket got the best of the tube. Months ago before any of the socket issues developed I put and International Servicemaster in the set and it only lasted a few minutes. The one that I just pulled out and tested bad was used before that and up until the socket issue of late. Hopefully another decent quality tube will take care of things.

For the price including free shipping, I would definitely give it a try if the set was on my workbench. The advantages of the solid-state replacements are: reduced loading on the horizontal output tube and flyback, as there's no filament to heat up, and you can drastically simplify the connections to the socket. Literally all you need is the connection to the anode lead/HV regulator tube coming out the bottom. I'd unhook the filament loop, insulate the ends, and tuck them away in case they're needed in the future.


The voltage withstanding and current handling capability of the S-3AT2 replacement exceeds the specs for the normal 3AT2 (A/B) series.

Thanks Dave! That should help a lot.

Anyway, today I got everything reassembled and powered it up. Nothing bad happened, but nothing good either. No HV and only a blue glow in the top portion of the rectifier. I put it on my B&K tester and it is dead as a doornail like the heater is open.

Not sure where or why that would have happened. So, now I will hunt another 3AT2. A local supplier here has International Servicemaster brand which I don't want to get. If anyone has a supply of these and needs anything of that style base; I have a box of these type tubes which I have no use for including some pretty expensive sweep tubes. Just throwing it out there.

Send me a PM with your email address and I can send you the full resolution pictures of the schematics. Upload to this site compresses the heck out of them and makes them look really fuzzy. A quick look at http://www.vacuumtubes.net/Prices%200A1%20to%203Z4.htm
shows they sell 3AT2s for $3.00. Other places are probably similar prices. I usually get two of each tube I order to have a spare and in case one is not so good.

Actually, a bad 3AT2 matches the Goodman description of the burnt resistor problem.

Dave

For the price including free shipping, I would definitely give it a try if the set was on my workbench. The advantages of the solid-state replacements are: reduced loading on the horizontal output tube and flyback, as there's no filament to heat up, and you can drastically simplify the connections to the socket. Literally all you need is the connection to the anode lead/HV regulator tube coming out the bottom. I'd unhook the filament loop, insulate the ends, and tuck them away in case they're needed in the future.


The voltage withstanding and current handling capability of the S-3AT2 replacement exceeds the specs for the normal 3AT2 (A/B) series.

The only time, I used a SS replacement, was when the filiment loop was punctured through and arcing. I cut it short or tried to remove it completely.
Never had any problems. Usually on an RCA or one of the clones.

The only time, I used a SS replacement, was when the filiment loop was punctured through and arcing. I cut it short or tried to remove it completely.
Never had any problems. Usually on an RCA or one of the clones.

Well, I sort of opt for originality when possible, so I called that supplier that Zenith6S321 posted a link for and have a couple of those and one or two other radio tubes I needed on the way. I inquired about what brands were available and was blown away as the guy named almost anything one would desire or not (International Serivicemaster). They actually had Zenith and put me down as preferring that. As a second option I told them Sylvania. I don't think I can go wrong with either of those.

Well, I sort of opt for originality when possible, so I called that supplier that Zenith6S321 posted a link for and have a couple of those and one or two other radio tubes I needed on the way. I inquired about what brands were available and was blown away as the guy named almost anything one would desire or not (International Serivicemaster). They actually had Zenith and put me down as preferring that. As a second option I told them Sylvania. I don't think I can go wrong with either of those.

IIRC, the original 3AT2's were made by GE. The Zenith replacements were made by Sylvania.
You should've mentioned the 3AT2. I could've included a good used one or two. :thmbsp:

IIRC, the original 3AT2's were made by GE. The Zenith replacements were made by Sylvania.
You should've mentioned the 3AT2. I could've included a good used one or two. :thmbsp:

All is well that ends well with that. They did send me 2 Zeniths, so I will have a couple of good NOS tubes. I haven't had time to try one in my set yet. A third and different tube for a 40s radio was a Ken-Rad. I've had some, but I can't remember how they held out. Shouldn't be a problem. I sent you a PM.

All is well that ends well with that. They did send me 2 Zeniths, so I will have a couple of good NOS tubes. I haven't had time to try one in my set yet. A third and different tube for a 40s radio was a Ken-Rad. I've had some, but I can't remember how they held out. Shouldn't be a problem. I sent you a PM.

Ken-Rad was one of the oldest tube suppliers out there. Their tube stood up as well or better, than a lot of the other brands. :thmbsp:

OK, I just figured out that I have been using Sams Set 722, Folder 4 which is for the 25LC30/U! Geez! It only specifies pins 1 &12 as heater connections. I need to get a .pdf on my 25MC30 somewhere. H

For the sake of this thread's information being accurate I must correct what is quoted above. My set's chassis is indeed a 25LC30 and the model is 5111. I don't even know where I came up with 25MC30 being what mine is. I am guessing that the L & M identifiers must have to do with production year. Mine should be the 1964 and the MCs should be 1965 and the last of that style plain metal cabinet round crt TV production.

Thinking I had the wrong schematic, I ended up finding a .pdf Sam's folder on the 25MC30 and was happy. Looking over the horizontal output and HV sections of the schematic I noticed that the 6JS6 horizontal output tube was used. I knew that my set employed the 6HF5 sweep tube. That led me to look at all the models covered for that year 1965 on the first page. I saw that the models were all different and mine 5111 was not there. I think instead there is a 5211 which is probably that year's equivalent. From there I opened my original file for the 25LC30 and saw my model and the right 6HF5 sweep circuit

In a way I wish that my mistake was correct as I have heard that the 6JS6 H Output tube was a better tube by design (plus I have a few in my useless compactron box). I don't think that they are subs for one another, so I won't even worry about that. The 6HF5 seems to do as well as any. I'm not sure how many other changes that there were in that one year. Most everything I glanced at looked the same. I notice Zenith regularly made small changes such as one or two tubes from year to year. That's the world of engineering for better or worse. I wonder how much better the 6JS6 really is just out of curiosity.

Anyway, I think the confusion on my part started with all the talk about the HV rectifier pin #s shown on my LC schematic. They appear to be wrong as pins 1 and 12 are shown to apparently be the heater terminals. Well, they are and they aren't, but you have to have the tube data to see what is going on internally with the 3AT2. Many pins are duplicate or NC. The MC schematic shows the same thing and it thew me off because I expected my set to be wired like the schematic as I would think a factory would adhere to; evidently not so.

If anyone here needs a good copy of the 25MC30, I now have it and would be glad to share it with anyone. Just let me know....:thmbsp:

OK, it's official! My HV is back. The surgery was a success thank goodness. I was a bit nervous of what new surprises may arise, but the only changes were definitely positive. Good, stable HV with no corona hissing and/or related screen anomalies.

I did use Electronic M's advice and paralleled a .47mfd cap across my meter leads measuring cathode current at the horizontal output tube. The readings were the same and unfortunately still a bit higher than I want, or Zenith wanted for that matter. The spec is 200mA and at line potential upward of 120VAC I get about 220mA. So I still run the set on my Select a Volt at about 110VAC and can maintain 200mA. Once an older tech said that they used to dip all the Zeniths at 210mA as a rule, but I feel that I should be able to achieve the spec. Now I do believe that the fly is now running much cooler for whatever reason. VERY happy there!

I probably just need to change out the HO coupling cap to get the 200mA. That should be next because for whatever reason I have to throw a bit more line voltage at the set before the color will come in. Once it comes in I can back it down. The color problem has been with the set since I brought it home. Actually, there was no color for a long time and I changed out the 6GH8 one day and had a DVD player hooked up and wa la. Great color!

For now though I'm just glad to have a playable set again. Many, many thanks to all for the help on this!

OK, it's official! My HV is back. The surgery was a success thank goodness. I was a bit nervous of what new surprises may arise, but the only changes were definitely positive. Good, stable HV with no corona hissing and/or related screen anomalies.

I did use Electronic M's advice and paralleled a .47mfd cap across my meter leads measuring cathode current at the horizontal output tube. The readings were the same and unfortunately still a bit higher than I want, or Zenith wanted for that matter. The spec is 200mA and at line potential upward of 120VAC I get about 220mA. So I still run the set on my Select a Volt at about 110VAC and can maintain 200mA. Once an older tech said that they used to dip all the Zeniths at 210mA as a rule, but I feel that I should be able to achieve the spec. Now I do believe that the fly is now running much cooler for whatever reason. VERY happy there!

I probably just need to change out the HO coupling cap to get the 200mA. That should be next because for whatever reason I have to throw a bit more line voltage at the set before the color will come in. Once it comes in I can back it down. The color problem has been with the set since I brought it home. Actually, there was no color for a long time and I changed out the 6GH8 one day and had a DVD player hooked up and wa la. Great color!

For now though I'm just glad to have a playable set again. Many, many thanks to all for the help on this!
Have you tested all the tubes in the color section? If not I recommend doing so. My set had no color, then I tested the tubes in the color section, and found most were testing bad to very weak. After replacing all the color tubes that did not test decently the color section came back STRONG.

...for whatever reason I have to throw a bit more line voltage at the set before the color will come in.
Are you familiar with the color killer adjustment?
To set it, you first turn the color control on full, and go to a snowy screen. There should be color speckling in the snow. If not, turn the color killer to the threshold point where color first appears in the snow, then back just a hair. That's the correct setting.

Of course this is assuming the tubes are all good.

Great hear you got the HV problem solved and the set operating again. Good tubes and caps can make for big improvements.

Dave

Have you tested all the tubes in the color section? If not I recommend doing so. My set had no color, then I tested the tubes in the color section, and found most were testing bad to very weak. After replacing all the color tubes that did not test decently the color section came back STRONG.

I did test the tubes a long time ago on my Hickok 6000A. I think I will do it again on my new B & K Precision 747. Oddly, I get color when the set wants to and when I do it is beautiful. It always seems to happen when I use a DVD/VCR combo and run the line E up a bit. Coincidence perhaps.

Old_coot88 mentioned the color killer adjustment. I am guite familiar with that adjustment. Worked with it last night and got the snow and color fringing. I backed off till that went away, and then a little more as some fringing was still there. The idea which follows common procedure is to shoot for the perfect black and white picture which I can achieve pretty much. Once I get the color actually working regularly I will go through the whole purity and convergence procedures using my vintage RCA dot bar generator.

While chasing the intermittent-color problem, leave the color killer adjustment full 'on', all the way to the stop, while troubleshooting.

In fact, you could leave it full 'on' these days, since everything is broadcast in color. Whereas in the old days when some broadcasting was still in B&W, the color killer circuit served to turn off the chroma to prevent color artifacts in the BW image.
It works by sensing the presence or absence of the burst signal.
Today, that function is moot unless something is being transmitted in actual (burstless) BW.

So if I leave it (killer) on and when everything is as it should be, the snow will more or less go away. I had assumed that not to be the case and setting it too high would be about like setting AGC too high. I fully admit more or less being fairly new to troubleshooting vintage color television beyond that of normal static convergence and other setup procedures.

This is the only vintage color set in my ever smaller TV collection (due to space and sanity). My primary interests have always been in earlier black and white sets and radios. I have owned a number of round tube color sets back when they were available very cheap and made great daily use sets. So bringing one back from decades of dormancy is new to me.

Thank God for the incredible pool of great people and knowledge here at VK to pass along what I as an electronics professional consider a lost art in the field that will vanish if not somehow kept alive. These days there are 'techs' who can barely read a meter; and I mean DIGITAL! They could care less about Ohm's Law, Kirchoff's Law,etc. To avoid a rant I will end this now as I must or that is what it will become.

So leave it on and when everything is as it should be the snow and fringing will more or less go away. I had assumed that not to be the case and setting it too high would be about like setting AGC too high. I fully admit more or less being fairly new to troubleshooting vintage color television beyond that of normal static convergence and other setup procedures.


The color killer has nothing to do with convergence. If the set has color fringing from imperfect convergence, the color killer will not make that go away even if cranked to the B/W only end. Use a test pattern to get the static (center) convergence perfect, then adjust the killer so that the perfectly converged portion of the screen (center) has no confetti (ie color snow), and ignore any fringing from mis-convergence elsewhere on the screen.

The color killer has nothing to do with convergence. If the set has color fringing from imperfect convergence, the color killer will not make that go away even if cranked to the B/W only end. Use a test pattern to get the static (center) convergence perfect, then adjust the killer so that the perfectly converged portion of the screen (center) has no confetti (ie color snow), and ignore any fringing from mis-convergence elsewhere on the screen.

Sorry, I need to watch my terminology a bit better and give more precise descriptions. I will edit my post a bit. I did realize that the fringing would be there either way as far as the color killer went. When I mentioned everything (at times) being as it "should be" I meant when the color actually has worked and worked well. The fringing I mention is due to myself or someone turning the convergence clover several degrees.

Shouldn't I do a purity setup before any convergence?

If the purity is good one can often adjust the convergence without having to mess with it.

So if I leave it (killer) on and when everything is as it should be, the snow will more or less go away. I had assumed that not to be the case and setting it too high would be about like setting AGC too high. I fully admit more or less being fairly new to troubleshooting vintage color television beyond that of normal static convergence and other setup procedures.

This is the only vintage color set in my ever smaller TV collection (due to space and sanity). My primary interests have always been in earlier black and white sets and radios. I have owned a number of round tube color sets back when they were available very cheap and made great daily use sets. So bringing one back from decades of dormancy is new to me.

Thank God for the incredible pool of great people and knowledge here at VK to pass along what I as an electronics professional consider a lost art in the field that will vanish if not somehow kept alive. These days there are 'techs' who can barely read a meter; and I mean DIGITAL! They could care less about Ohm's Law, Kirchoff's Law,etc. To avoid a rant I will end this now as I must or that is what it will become.

You mean to say, they don't know Thevenin and Norton's theorem either? :D
I'd have to get back to the books! It's been years. :sigh:

You mean to say, they don't know Thevenin and Norton's theorem either? :D
I'd have to get back to the books! It's been years. :sigh:

No they don't. Ohm's law would be the only thing that a modern JR college curriculum would include and perhaps Kirchoff's Law; and that would be very limited. I don't mean to put the younger techs down for what they were never taught. I just think that it's a shame that what was once a respectable discipline that was pretty darned involved and anchored in the roots of the science of electricity/electronics has like so many things been dumbed down so, yet the students attain the same credential as students of old who I feel had to work harder to get what they got.

I have been told that my mindset on this suggests that I or anyone else should attend a university. I say that's wrong because you are not going to perhaps get through a high school trades course and then get a couple of years of college under your belt to find yourself beginning the theories and the math to prove them which is the foundation for all of what we do when completing your Bachelor degree which at that point would be electrical engineering. I guess there are better and worse JR college programs and a lot of what I remember was a bit of a joke. And that's back when it was a lot harder than today.

I remember an exam question on the definition of voltage. The correct written answer was "a force." Sure, it's a force. So was a big part of Star Wars! Just an example. I am told now that they have almost completely converted the focus to what is known a Mechatronics. Basically automation, so some factory can get you to be the grease monkey and the electronics tech. The I.T. guy gets an office! So the college tossed a truckload of oscilloscopes, function generators, Variacs and other great tools in the dumpster one day. You couldn't even buy them as they were government property to be destroyed. I won't bother going into grading most tests based on the lowest grade so basically nobody flunks out. Money!!!

OK folks, as promised; here is where I stand. I didn't want to post pics until I had a decent color picture. I think I found and tested 10 6GH8 tubes before I found one even marginal one one of the two tests for that tube. The rest were LOW emissions. I have heard that the 6GH8s were lousy tubes and my B & K Dynajet 747B sure proves that. I notice that there are some common subs like 6U8 and 6EA8 that may work, but I had none on hand. Anyone every tried any other subs?

But as for the whole HV rectifier project; it looks like a wrap. Very stable and still using a slightly reduced line voltage I can maintain less than 200mA at the horizontal output's cathode. The fly seems to be running cooler than it was when I had the old socket and corona hiss. I absolutely love that silence and a cool fly.

I am really surprised at the generally good color picture with really no alignment. Not proper anyway. I did set the service switch and touch up the guns to get as good a white line as I could, but there really wasn't much to do there. Next comes the use of the same age RCA dot bar generator as up close there are obvious alignment issues. I think it will be stunning when I work those out.

Thanks again everyone for the help on this!

Tube

Lookin' good!:thmbsp:

Good job!:banana:

Heck, I learnt sumpthin' too.. the resistance wire used for the 3AT2 filament.:o

Nice work.:thmbsp:

Thanks to Electrronic M, Zenith6S321 & Old_coot88 for the kind words. I tell ya; one thing about messing with old TVs (especially color) is that there is always a new mystery or maybe some adjustments around the corner. The lovely pic of Ray Charles was actually taken with the set on it's side for service next to (of all things) my Frigidaire.

So, I'm finally ready to set her down for normal viewing and powered her up; color gone. And my black and white wasn't so black and white anymore. The intermittent color I deeply feel is that darned 6GH8 Chroma Reference Oscillator that I mentioned in an earlier post. What is up with these 6GH8s?!?!? Anyway, I think the rest of my impurity is a magnetized C.R.T. or simple purity adjustment as I had moved the rings some while it was on it's side.

I may be able to dig a couple of healthy 6GH8s out of my tube stock for you if you need them.

When I first started on my 29JC20, the color would work but then quickly fade away as it warmed up. Is that what you see, or is there no color when its powered up cold?

I may be able to dig a couple of healthy 6GH8s out of my tube stock for you if you need them.

Make sure you test any used with something like a B&K 747. I have so many tubes from Zeniths, I sent Greg a variety of tubes for his set that tested great on my emission tester and they failed on his.:no: Since I now have three of these Zeniths, Im really paying attention so I can maybe solve some of these riddles for the benefit of all.

Anything octal/loctal or newer I test on a B&K 606 (it works good so it is all I use where applicable).

I may be able to dig a couple of healthy 6GH8s out of my tube stock for you if you need them.

That would be cool; really cool. Even one good one would be nice. Also, as it was brought up, I use a B & K Dynajet 747B these days for the most part or sometimes a Hickok 6000A, so I have little fear of mis-testing. I have seen it on a plain emissions tester that I have by Accurate Instrument Co. Almost all tubes test good. Weird! :scratch2:

Also, I found a bad 6KT8 last night and sort of ended up in the same situation with a bunch of bad ones. Several were the ones that Dave sent me and a few were my own. I have one more box to check for others, but may need one of those if plentiful. Let me know what you find Electronic M. Thanks!

When I first started on my 29JC20, the color would work but then quickly fade away as it warmed up. Is that what you see, or is there no color when its powered up cold?

No, I don't see the former, but I do see the later. My set often (more than not) starts off in pure black and white with the exception of impurities now that my Frigidaire magnetized my tube or possibly other adjustments like purity rings need to be adjusted. Anyway, no color until after quite a bit of warm up. Maybe 20 minutes or so. Once it's there, then it's there to stay normally till I shut her down.

As previously mentioned, I am working with more than one marginal at best tube in the color circuits. That may be the whole thing. I hope so because I want to get this thing stabilized and get my same vintage RCA color dot bar generator hooked up and do her up right! :thmbsp:

(Edited cause I forgot this is not a 29JC20!)

It still could be an effect of the Zenith automatic control control/color killer that caused my color fading issue. One way to see if that's it is to disable the color killer. If your color comes back then its not the 3.58 MHz oscillator that is causing the problem.
Dave

That sounds like a good idea. I will keep it in mind. Tonight I powered it up and it almost seemed like color wasn't going to come in. I started tweaking the killer and the tint and the color just came in. I REALLY need to get into some purity and static convergence when I get stronger tubes in there. I tested my 6KT8s on my Hickok and the Accurate Instruments for comparison. All good on the Accurate and all weak on the Pentode test with two having marginal triode tests. I used the stronger one of course. I think that the color takes so long to come in due to the marginal emission and a usually reduced line voltage causing slower. I have noticed that I can bump up the line voltage and shortly thereafter the color will come in; then I can back off to ensure the 200mA horizontal output cathode current and the color will remain.

Question: When I am setting up my convergence clover, is the black line on the crt's gun an index as to where the plastic edge of the clover should go to have it directly over the beam converging pole pieces? Some of this has been moved and I want to have it dead on so I can slide the yoke back and work my purity rings for a red center; then move the yoke back till I achieve the best red screen possible. This of course with the other two guns extinguished.

Ignore the test point from my previous post. I was thinking this was a 29JC20, so your test point is probably labeled differently.

Here are pictures from Goodman of the CRT pole piece positioning for roundies.

Ignore the test point from my previous post. I was thinking this was a 29JC20, so your test point is probably labeled differently.

Here are pictures from Goodman of the CRT pole piece positioning for roundies.

Wow, small world. I have those two shots in a (one of many) book I have called "Color TV Servicing Made Easy" by Wayne Lemons and Carl Babcoke. It's a Sams publication and is wonderful. Guess that makes me look pretty bad, but there is a method behind my madness.

The book simply says to position the clover "directly over the convergence pole pieces." It even shows what that is as seen in the electron gun breakdown. My question was derived from the fact that the area is blacked out where you don't see the pole pieces. The blackened area clearly ends about where the clover should be. I thought perhaps the black line could be a reference point placed as the pole pieces can't be seen. I'm not sure of the distance toward the yoke that this black area goes.

I am trying not to move things a lot as I have pretty decent color. I have moved the clover enough to see that it's placement forward or back even a small distance makes a big difference in alignment. I guess I may as well just slide everything back and see if I can view the pole pieces. After all, I could be having to put in a new crt and be removing all of this stuff anyway. I just thought that if this were an indexing mark it would be nice and useful too.

I went ahead and just placed the plastic edge of the clover right at the metal disc for the pole pieces which is all you can see. I loosened the yoke and pulled it back and turned all but the red screen down and tried to move the rings to get a red splotch somewhere near center. Unfortunately, I can't get a red splotch at all as I have seen in some good YouTube videos by a member of VK. It seems I can conjure up all kinds of combinations of colors and even almost totally blue, but no red center.

So I just got it as red as I could and slid the yoke back. Definitely more to do there. I had to just further manipulate the rings at that point to get a somewhat uniform red screen. I really think that I need to get a degauss-er for one thing. I wonder if some magnetization could keep me from achieving the red center on that procedure....

Manually degauss, and if that fails move the yoke farther back (even if you temporarily have to slide the convergence yoke back a bit to make it work).

Manually degauss, and if that fails move the yoke farther back (even if you temporarily have to slide the convergence yoke back a bit to make it work).

OK, that sounds reasonable. I will try moving the yoke back as you said and see what happens. I don't have a degaussing coil, so I may as well try whatever I can. Those weak tubes I feel still have me waiting a long time for color, but at least I know that it will usually come in.

I have an RCA WR-64A color dot bar generator that I hooked up just for the heck of it and the thing worked for a few minutes and then my sync started going whacky. So I put it on my daily watcher and the same thing happened, which to me was good as it told me that it wasn't some issue with my old Zenith. I smacked it on the side (generator) and the sync problem went away. SO, I probably need to clean up some tube pins and sockets and I will have that rather handy unit ready.

Never a dull moment in this saga! BTW, I know they make DVDs now for alignment. I'm sort of a fan of vintage test/setup equipment and it was a gift, so I may as well put it to use.

If you can find a curbed 27" BPC TV set with a single large degauss coil, then you can salvage the coil from the BPC, loop that large coil into a ~15" smaller coil, and attach a cord to it, and use it as a degaussing coil. This ad-hock degauss coil may only last 1-5 minutes of 120Vac at a time before overheating so keep an eye on the temp and work fast if you use this method. I made a backup coil that way, and it works decently.

GREAT! Moving the convergence clover back along with the yoke allowed me better purity adjustment. Not having a true technicians degaussing coil, I just got out my Weller soldering gun and used it like a coil. The trick worked great! I'm a bit embarrassed as to worrying so much about positioning my convergence clover perfectly. I have learned through trial and error that indeed we often need a pointer, but sometimes ya just gotta jump in there and see what things do.

If you are a tech or minded as such, then you know to mark and or document in some way the way things were before you moved or adjusted this or that. Our training or experience taught us not to go 'tweaking' this or that until you have reviewed some technical data and at least have a rudimentary understanding of what a device, circuit or adjustment of either will or does do. And when in doubt, ask a question. I don't know what it is with some of us, but we would rather noodle with a $10K piece of equipment and sometimes ruin it than to simply say I don't know for sure what is going on with this, anyone got some advice. Geez!:no:

I saw that enough in the work place to not want to be 'that guy' and it's why I don't mind asking things that may sound ridiculous to some of the seasoned veterans of the golden era of electronics. I work on high dollar automation every day, but I need help sometimes with REAL electronics that's decades old. Having this place to gather that pool of knowledge is invaluable and a blessing. Thanks again to ALL here who have helped.

I thought someone might enjoy tonight's screen shot of Cream's reunion show at the Royal Albert Hall a few years ago. Ironically, it's where they did their "farewell" jaw dropping final performance back in 1968. I tell ya, audiences of today may as well be dead people compared to the crowd in 1968. The band more or less holds it's own to be the age they are now. Great DVD if your into Blues/Jam/Rock. They were their own unique genre.....:smoke:

If you can find a curbed 27" BPC TV set with a single large degauss coil, then you can salvage the coil from the BPC, loop that large coil into a ~15" smaller coil, and attach a cord to it, and use it as a degaussing coil. This ad-hock degauss coil may only last 1-5 minutes of 120Vac at a time before overheating so keep an eye on the temp and work fast if you use this method. I made a backup coil that way, and it works decently.

I saw a lot of them made of aluminum wire. Doesn't really make any difference, just an observation of mine. It probably takes a few more turns to produce the same amount of flux.
Maybe taking a 60 or 100 watt lamp and connecting it in series would produce enough magnetic flux to be effective, without burning up. :scratch2:

I saw a lot of them made of aluminum wire. Doesn't really make any difference, just an observation of mine. It probably takes a few more turns to produce the same amount of flux.
Maybe taking a 60 or 100 watt lamp and connecting it in series would produce enough magnetic flux to be effective, without burning up. :scratch2:

A variac may also do the job of limiting heat....I just hold it the whole time, and if it feels like it's getting hot pull the plug. I've done enough degaussing procedures now that unless there is a particularly stubborn magnetized region it's usually one fast fluid ~30sec action.

Interesting that they use aluminum wire. I've never removed the black plastic wrapping to check.

I still can't believe the job that my Weller model 8200 soldering gun did. Anyone ever tried this? I found it on the web as an alternative. I will say that it didn't hugely distort the raster the way a traditional degaussing coil does. Mine is 100/140 Watts. Not sure why it is listed that way.

I still can't believe the job that my Weller model 8200 soldering gun did. Anyone ever tried this? I found it on the web as an alternative. I will say that it didn't hugely distort the raster the way a traditional degaussing coil does. Mine is 100/140 Watts. Not sure why it is listed that way.

Pull trigger to the first click = 100 watts
Pull trigger to the second click = 140 watts

jr

OK thanks! I think my gun is as dated as most of my equipment. The packaging looks 50s or 60s. Great to know!

Not to derail this thread too far, but here is a nice page about Weller guns... 60s is a good guess for a 8200.
My first Weller was given to me by my parents when I was a kid (late 50s)... a 8100 K set. Later (late 60s) it was lost/stolen and I replaced it with a 8200, which I still use on occasion. My favourite soldering tool for most stuff is a WTCPN station, also shown on the page:
http://www.stevenjohnson.com/soldering/weller.htm

jr

Not to derail this thread too far, but here is a nice page about Weller guns... 60s is a good guess for a 8200.
My first Weller was given to me by my parents when I was a kid (late 50s)... a 8100 K set. Later (late 60s) it was lost/stolen and I replaced it with a 8200, which I still use on occasion. My favourite soldering tool for most stuff is a WTCPN station, also shown on the page:
http://www.stevenjohnson.com/soldering/weller.htm

jr

I got my Weller 8100K for Christmas, December,1956. Man! Was I proud of that thing. The next gun, I bought was the Weller D440. 150/210 watts. It uses the 8100 tip and is ideal for most soldering. I think Weller quit making it in the late 60's. All the Weller guns I have now, came from garage and estate sales. I won't buy the newer ones with the set screws. :sigh:

I got my Weller 8100K for Christmas, December,1956. Man! Was I proud of that thing. The next gun, I bought was the Weller D440. 150/210 watts. It uses the 8100 tip and is ideal for most soldering. I think Weller quit making it in the late 60's. All the Weller guns I have now, came from garage and estate sales. I won't buy the newer ones with the set screws. :sigh:My D440 has a few cracks in it but makes a great degausser in a pinch.
I got a near perfect 8200 for $10, tried to keep a poker face as I dug out a note:D

I'm glad to hear the good press on the older Weller soldering guns. I guess I didn't really know what I nice gift my girlfriend bought me. Yep, the same woman who would LOVE to see the Zenith in the kitchen vaporize as well as the 5 other sets that she widdled me down to. Actually, she does see some charm in a 1950 RCA TC-127 in the living room, so it may have hope of a long and healthy life.

But she brought home this Weller in it's factory gray case with a nice piece of period advertisement inside the cover as well as the Styrofoam insert that seems impossible to pack it in. Actually, I think it broke in two on my last attempt, so I keep the gun on the shelf. We have a newer one at work that is the same size, but feels like a toy in your hand compared to the old one. Great stuff!

I was able to find 3 used 6GH8s that test as good as new and a NOS 5GH8 (which should not mind an extra volt on the heater from a transformer powered set).
I'm trying to scare up some 6KT8s too...I found 3 that were less than great, but I've only searched a fraction of my unsorted stock of that era of tube so far.

I was able to find 3 used 6GH8s that test as good as new and a NOS 5GH8 (which should not mind an extra volt on the heater from a transformer powered set).
I'm trying to scare up some 6KT8s too...I found 3 that were less than great, but I've only searched a fraction of my unsorted stock of that era of tube so far.

Anything helps and thanks. Don't put yourself out too much searching through tubes. That 5GH8 may be what the set needs. Exactly right on the extra volt. It may be what the set needs right now as I continue to run on reduced line voltage to control HO cathode current. I am at about 110VAC right now. It seems to get a little better with time as do a lot of dormant electronics I have dealt with. You get past the initial phase of feeling good powering up without hot caps and transformers and then you can let a device sort of "reform" its self.

That term "reform" is probably what goes on really. A decades long dormant set gets playtime and the caps (if they made it that far) may sort of reform or rejuvenate themselves. Some people don't believe it, but I have seen it many many times. I heard these 60s color sets, particularly Zeniths' often come back from the dead like new. That's more or less what happened with mine. I put a new cap across the horizontal efficiency coil as I was installing it anyway and will likely replace the coupling caps in the same circuit. That's about it....:thmbsp: