Is it the CRT or ???
 

Lately my Zenith Chromacolor II has been having an issue and I'm not sure if it's a gun in the CRT or one of the boards that controls tone. I'll be watching and all is well, but out of nowhere the screen will flicker and take on a light to very dark magenta tone. Sometimes it will stay this way for a bit and other times it will go away in seconds. I can go days without it happening.

I know it's not the video driver board as it is a new board and this happened with the old board. I did a test of the CRT and even did the rejuvenation. All is well as far as the testing unit is concerned. I've even removed all the modules, cleaned the contacts and replaced. None of which helped.

I am about to catalog all the main caps to replace them as I have jailbars and a medium dark horizontal line that moves up the screen. I'm not sure they would have anything to do with the problem, but need to be done anyway.

So, any suggestions?

Thanks in advance.

model or chassis number might help.

Clean the chromatic switch (if it has one) and clean all module contacts with deoxit. I guess it could happen; but, I've never seen a shorted/intermittent CRT in one of those. Those were some of the most reliable CRT's ever made.

Thought it was in the info at the bottom of my posts, but I guess I forgot to add it.

It's a Zenith 19JC55Z.

Do you mean the "Color Sentry" button? The one that opens up the light sensor to make automatic adjustments? If so, how should I go about cleaning it so as not to harm the sensor in it?

I've already removed all modules and cleaned the contacts with deoxit.

The board pin connectors are known for bad connections.

The video drive board has a big white flat upright assembly on it with many PC connections. I've re-soldered these with good results in the past.

CRT could be bad, but I tend to doubt it, being a Zenith.

I've done about all I know to clean and reseat all the modules. Is there a trick to get better contact?

The video drive board is new (well NOS) and it had the same issue with the one it replaced. Unless something else is causing an issue with the video drive board.

dirty G2 pot (green).

The G2 is on the video driver board and it's a new board. The issue also happened with the old board.

Can you monitor the voltage going to the CRT at the connector there on the video module for each of the R-G-B sources?

If the voltages are not changing, there might be a reason to suspect the CRT...

Even with that, have you tried tapping the neck of the CRT with a pencil while watching the screen? Does the problem go away? Best of luck to you, friend. I love the CC-II Zenith's.