Attempting to resurrect my 1968 Panasonic

[jpdylon]

This was a set I got awhile back from Adam. It was a strange, rare one so I couldn't really leave it. My mistake was using it un-restored. One day something happened and there was a loud POP. No smoke, just nothing. I had lots of other work to finish so it sat for almost two years. During the time it sat it took up space and became an eyesore. No one would even take it for free.

Since I started feeling better I Recently decided to get back into the panasonic. I figure since I can't get rid of it and I don't want to crush it, I'll fix it up. I believe its a model CT-66 from 68. It is truly a marvel. All hand-wired chassis similar to zenith design, very well made power supply, soft start, and great HV regulation and DC restoration. I lightly refinished the cabinet while the chassis was out.


I replaced all of the original oil caps, power supply electrolytics, and even paper wax caps --that's right someone was still using paper wax caps in 1968. Scary, huh?


A short in the HV regulator about scared me half to death when I first fired it up after the recap. A loud hum followed by a really bright blue flash from the HV cage got my heart goin. Replaced the HV regulator, and rectifier and tried again. This time I got a nice bright raster with a razor sharp picture. All seemed ok for awhile.

Then a vertical defect showed up. The picture began to erratically move up and down. The blanking information is now hanging around the center of the screen. The sync pluses are clean and the vertical locks perfectly. You can also hear a slight sputtering in the sound at 60hz (sounds like a sawtooth.)
I have not been able to resolve the problem as of yet.



If anyone could get me some service literature on this set or point me in the right direction, I would sincerely appreciate it. This set is going to be a daily watcher and I want it to work right.

[Chad Hauris]

Could there be some kind of feedback or leakage maybe in the yoke itself or in the pincushion or convergence circuits...something off of the vertical output transformer that is introducing trash into the signal?

[jpdylon]

I'm hoping that the problem isn't in the yoke.

I'm going to go over the vertical sweep with a fine tooth comb this week to see if I can find anything I may have missed earlier.

I didn't think of the convergence assembly. Could a fault there really cause that kind of problem? Is there a way I can operate the set without the convergence board in circuit as a quick way to see if that is the problem?

[andy]

000

[jpdylon]

I've fiddled with height and linearity as well as the centering control. All function well with no dead spots. If I adjust the size or linearity there is no foldover.

The picture looks shifted due to me fiddling with these controls.

[andy]

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[jpdylon]

I also notice that along with the sputter in the audio, you can crank up the color and see colored snow -much like the look of ignition noise.

If I force the picture to roll and try to hold the blanking bar in the middle of the screen, the bar will jitter up and down erratically much like the picture is when its locked.

it is odd. If I had some service literature I might be able to track it down quicker.

[kx250rider]

That is indeed strange, but I will put my vote on a cap failed somewhere in the vertical. That looks like a Toshiba chassis... So for literature, I'd try Sears and Toshiba Sams from the mid 60s.

Charles

[bgadow]

I just dug out some Sams. There is a CT-66 and a CT-66N. I suspect the differences are minor as the tube lineup is all the same. Neither looks like yours from the outside but the under chassis shot matches. These are in Sams 838-3 (9-66) and 931-1 (1-68). If you would like to borrow my copies send me a PM with your address.

[jpdylon]

The chassis is stamped CT-66Nc. The cabinet was made for Edmon's Dept stores in Canada, which might explain why the cabinets don't look the same.

Brian, I may hit you up to borrow a copy of the CT-66n sams if I can't figure this out myself.

I noticed some capacitors tucked behind the vertical output transformer that appear to be across some windings. I'll be able to pull the chassis and replace those wednesday to see if those are the culprits. 40+ year old electrolytics can't be good.

[jpdylon]

I've been all over this set and I still cannot seem to relieve the problem.

All of the electrolytic and film caps have been replaced in the sweep sections. I've checked and re-checked wiring, resistor values, etc.

If you decrease the vertical height, the problem remains but you can see a better view of it. It does appear to be a fold over at the top of about 30 lines or so. This is the reason why I'm seeing blanking information in the upper part of the screen.

Tubes have been swapped too. I'm not sure what else could be the problem. Yoke defect maybe? I hope not.

[Sandy G]

It's haunted. (grin)

[bgadow]

I've seen bad pots in the vertical do weird things.

[andy]

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