Zenith Chromacolor II (Ch. 19EC45) 19" color tabletop TV repair log

[cj_reha]

Good news, it's alive!

I finished the project that had been occupying my bench for a good few weeks (recapping and repairing corroded traces on a Panasonic Travelvision 1.5" portable set from the early 80s), so I figured I'd dig the Zenith out and attempt to get it running again. I decided to go the ghetto route and just parallel six of my .0018uF caps together into a sort of "flower" formation and tack them to the back of the flyback for easier access. In the future I'll likely order the "correct" part, but I'm really cheap and this solution works just as well. I also replaced the vertical fuse - it is a 250V, 0.6 amp part for anyone who might have this problem in the future.

Fingers crossed and prayers said, I hit the power...it came right up! Everything was horribly misadjusted, but after a bit of tweaking I was able to get a pretty respectable picture out of it.

However, that victory was short lived. I was tweaking convergence and focus when the picture suddenly started shrinking, followed by the circuit breaker popping. It now does not stay on for more than a few seconds before the breaker pops again, so I've stopped powering it on to prevent damaging something.

I have yet to dig into the set, but I suspect the big oil cap went open. It appears to be original, and according to a few videos I've watched it is a moderate failure rate part. More soon...

[zeno]

First you have to use the right caps for the 22-5001 or they will
short. See old threads for subs.
Hum then quick breaker pop is almost always the caps, damper,
hoz out or shorted oil cap. Longer pop ( apx 10-15 sec ) the
tripler.
Quick checks are unsolder one end of oil cap. If the cap opens
the pix will pulsate but work.
For H out just hang an ohm meter on the H. out collector to GND.
Should be in the megs. If shorted unscrew the H. out ( 121-831 ).
Then the damper ( 103-193 ) then caps etc...... Dont run with any
hoz parts unloaded. Oil cap you can run without a short time.
Last hint for now is all the original boards have plug in semis. The
sockets will get intermitant especially the IC sockets on the 9-86
color board.

73 Zeno
LFOD !

[cj_reha]

Originally Posted by zeno

First you have to use the right caps for the 22-5001 or they will
short. See old threads for subs.
Hum then quick breaker pop is almost always the caps, damper,
hoz out or shorted oil cap. Longer pop ( apx 10-15 sec ) the
tripler.
Quick checks are unsolder one end of oil cap. If the cap opens
the pix will pulsate but work.
For H out just hang an ohm meter on the H. out collector to GND.
Should be in the megs. If shorted unscrew the H. out ( 121-831 ).
Then the damper ( 103-193 ) then caps etc...... Dont run with any
hoz parts unloaded. Oil cap you can run without a short time.
Last hint for now is all the original boards have plug in semis. The
sockets will get intermitant especially the IC sockets on the 9-86
color board.

73 Zeno
LFOD !

Interesting - I did some reading, and apparently I can use an 800-860 as a sub. Is that the correct value? It is a later four lead cap but should fit. Will purchase one for experimenting.

Thanks for the troubleshooting tips, after I get the proper cap I'll start going through all the possible failures. I hope it's the oil cap, but it really could be anything.

[zeno]

800-860 is the kit for this chassis when it uses a 4 lead cap.
I never did the math on the mfd value so be sure.
The cap has 2 pairs of leads that each pair read a short. One
pair is used to complete the emitter circuit, the other the
collector. If the HV goes too high they open & kill the HV.
Personally I would stick with the 22-5001 or a proper sub.

73 Zeno
LFOD !

[Tim Tress]

I worked on dozens of them, when they were relatively new. Two other components to check; the damper diode under the horizontal output socket, and the feedthrough capacitor in the collector circuit of that transistor. For a quick check of the tripler, disconnect the output lead of the flyback transformer from the tripler, making sure to space the wire well away from anything that it could arc to. Apply power; if the breaker now holds, the tripler is shorted.

Also check the electrolytic capacitor and the rectifier diodes for shorts.

I have many modules for that chassis, if you should need any.

[Electronic M]

Originally Posted by Tim Tress

I worked on dozens of them, when they were relatively new. Two other components to check; the damper diode under the horizontal output socket, and the feedthrough capacitor in the collector circuit of that transistor. For a quick check of the tripler, disconnect the output lead of the flyback transformer from the tripler, making sure to space the wire well away from anything that it could arc to. Apply power; if the breaker now holds, the tripler is shorted.

Also check the electrolytic capacitor and the rectifier diodes for shorts.

I have many modules for that chassis, if you should need any.

On sets where the trippler may be bad but no breaker tripping occurs the trippler can be checked by measuring the boost voltage with and without the trippler....if is is low with and normal without you know the trippler is done.

[cj_reha]

It's been a while since I posted about this set (or on VK in general) so I thought I'd give an update! It was sitting in storage for a while and I finally decided to properly fix it since I know how well these sets perform and it's one of the sets in my collection I like the most.

I replaced all of the white safety caps with the one large four lead cap I soldered to the back of the flyback. It works fine so my math is correct, they do all add up to 0.01uF.

The breaker tripping/shrinking picture problem was indeed the oil cap in the PS as a few here suggested. It was getting untouchably hot before the breaker tripped. Mounted a new 3.5uF motor run cap, problem solved.

I also went ahead and replaced all the small electrolytics on the modules, resoldered some questionable joints and re-tensioned all the connectors and went over the convergence, just general preventative maintenance stuff. And I am pleased to announce it works amazingly well! I think it is one of the best looking color sets in my collection and I am very glad this set finally has a happy ending.

There is ONE more problem I will need to figure out once I procure (or borrow) a high voltage probe. I suspect it is producing excessive HV as even after thoroughly cleaning under the anode cap and the surrounding bell of the tube, it makes a continuous hissing sound and produces a lot of ozone. I've confirmed it's coming from the anode as bringing a screwdriver near it exacerbates the hissing sound, and once or twice I even got an extremely nasty arc that shot out from underneath the cap! The plastic does seem to be decomposing some (getting sticky and oily), so maybe it's becoming conductive? I also noticed the focus control needs to be at its extreme end for the picture to look good, so maybe that also indicates high voltage outside normal operating range? I know focus is often derived from the anode voltage though I am unfamiliar with whether or not that's true with this set specifically - I never did find a schematic for it. I will update if and when I figure that out, but for now the set works well and I am not extremely concerned.