Lately my set has been twitching in the tint area. Going from more green to more red. Every now and then it will go almost completely magenta. If I turn to a channel with no signal (snow), there will be bursts of blue and red color snow over the screen. In the past the snow was always black and white.

I know there's an adjustment somewhere in the set (I have to find my SM) that sets the cutoff or something so color doesn't make it into a black and white signal (snow). If I'm remembering correctly, it seems this board would be where I should be looking?

I've checked all the knobs and cleaned them with Deoxit and the problem is not affected by manipulation of any of those user controls.

Other than the unstable tint and it going magenta, the set works perfectly.

Thanks!

Look on the video output module for a resistor network. This will be a long thin ceramic substrate device with many terminals. This device gets very hot and the solder can break loose from the board. Try resoldering this resistor pack. Note that some of the earlier video output modules used regular resistors; so, this resistor network will not be found on the earlier modules. Also, make sure the module is seated firmly and making good contact with the chassis. You might also want to resolder the module contacts that connect the board to the chassis. Do the same thing to the chroma module if the problem still persist. Also, make sure none of the G2 controls are defective. Flip the set-up switch and set the G2 controls for a faint white line on the screen. There should be no sudden bright color burst on the screen as you adjust the controls. I've seen those G2 controls fail and cause erratic drive to the CRT.

The video output board is an NOS OEM replacement less than 3 months old. I checked the resistor pack and all the connections look good. I found my SM and readjusted the G2, brightness range, brightness limiter and color threshold. We'll see if it helps.

As for the modules and their connections... The video output is mounted to the tube neck, so there are no solder connections. As for the other modules, they also have no solder connections. They snap into place over metal connection posts. If I release the four plastic holders around any board, they simply pull out. Maybe I should remove each board and use Deoxit on the connection points.

OK, so you have one of the later chromacolor II's with the inline gun CRT if the video drive module plugs directly onto the CRT. Yes, it would be a good idea to pull each module and clean the contacts with deoxit. Also, clean the CRT pins and the contacts on the CRT socket itself. Check the soldering on all the module contact pins and resolder any that look bad. In fact, it would probably be a good idea just to resolder them anyway. I've also seen a dirty / defective chromatic or color sentry switch cause your problem.

I had a Zenith 1977 Chromacolor II that had the same problem from DAY 1.
Video boards were replaced to no avail.
Worst piece of junk I've ever owned. When I threw it curbside ---I hurled a brick thru the front of the screen. Made me feel so good.
James

Well I got rid of the unstable tint problem. Now I have an occasional burst of small green flashes over most of the screen. The green flashes are all different shapes and sizes. Some are small and round, others are long thin lines and others look like islands on a map (if all this makes sense). It doesn't do it for long and no other colors.

This TV has been in the family since '77 and has worked perfectly until the video driver board shorted. Maybe there's an issue with the repalcement video board. If the green doesn't settle down, I'll pull the board and go over it completely. It's not bad enough to get me to do it yet. I don't want to chance making it worse or causing another issue. I got lucky finding this OEM NOS video board and don't want to hunt down another.

Can I disconnect the color sentry switch to see if it helps, or does it need to be connected at all times (in use or not)?

I think the switch needs to be there at all times. Try the set with the switch turned off and see if any changes are noted.

Just because that board is new does not mean it does not have a fault. Most of these modules are actually rebuilt and I've had several zenith modules that were duds right out of the box, especially on the '80's and '90's sets. Also, try lightly tapping on the CRT neck with some sort of insulated tool. If the picture goes crazy, it's probably either a shorted CRT or something loose on the video driver module.

I think the switch needs to be there at all times. Try the set with the switch turned off and see if any changes are noted.

Just because that board is new does not mean it does not have a fault. Most of these modules are actually rebuilt and I've had several zenith modules that were duds right out of the box, especially on the '80's and '90's sets. Also, try lightly tapping on the CRT neck with some sort of insulated tool. If the picture goes crazy, it's probably either a shorted CRT or something loose on the video driver module.

I have tested the CRT with a tester and it is good. I did the neck tapping and there was no change.

I do plan on making this set a project in the near future. There are a number of components that caught my eye. There a large silver capacitor with two male screw terminals attached to the bottom of the chassis I'd like to test, etc. I've already replaced the tripler and video output board. Any other components I should be concerned with? I remember reading something about an orange capacitor?

I just wish that here in L.A. people wouldn't toss out everything on a regular basis. I have been looking for a nice console model, but haven't been able to find one. I really want the white chromacolor console. It's noted in my SM as J2540X. If not that one, then a nice wood cabinet unit.

That oval capacitor with the male terminals is in the power supply and operates in conjunction with the power transformer to regulate the B+ voltage. Those generally work or they don't work. I've seen them short a few times and the symptom will be a dead set for a few seconds and then the circuit breaker will trip.

There is a 10uf, 350 V electrolytic cap on the flat part of the chassis that is a fairly common failure. It is in the B+ line to the video output circuit. The failure of this cap will cause the left side of the screen to be darker than the right and can also cause a lack of picture sharpness.

The orange safety cap should not be an issue. If you find a Zenith with the WHITE cap, it should be upgraded to an ORANGE cap before you even think about powering up the set again! Those white caps can and will open without warning, causing the HV to run through the roof, which will break the CRT's neck off and possibly cause other damage. Rule of thumb: If it's WHITE, replace it! If it's ORANGE, leave it!

I think the switch needs to be there at all times. Try the set with the switch turned off and see if any changes are noted.

Just because that board is new does not mean it does not have a fault. Most of these modules are actually rebuilt and I've had several zenith modules that were duds right out of the box, especially on the '80's and '90's sets. Also, try lightly tapping on the CRT neck with some sort of insulated tool. If the picture goes crazy, it's probably either a shorted CRT or something loose on the video driver module.

i to had a ton of rebiult zenith modules that were bad out of the box.