Zenith CC II 19JC55Z tint and other issues

[TinCanAlley]

Howdy!

Okay, this issue is starting to drive me nuts. I'm hoping its just a simple connection issue and someone can point me to the board(s) in question.

When watching the set, the tint will jump back and forth between more green to more red (it's subtle, but noticable). Then it will jump from a normal picture to one with a very dark magenta tint and back to normal. This happens cold or warm and not consistantly. Sometimes I can watch it for hours and it never turns magenta or notice the tint changing.

The other issues is with either the brightness or contrast. I'll be watching and all of a sudden the picture goes to a negative looking image of just blues and reds and very dark. There are no whites or bright colors. If there is white text on the screen, you can't see it. I have to tap on the set to get it back. Knowing this I'm certain it's a connection issue, but I don't know where to start looking.

This set has boards that appear to be mounted in such a way that all you have to do is pull them to remove them, but I'm not 100% sure.

So, any ideas where to start looking? I have the color sentry turned off, but even when on, the problems still happen. I've cleaned all the knobs with Deoxit and lubed them with Faderlube, but this had no affect. This leads me to believe it's one or more of the boards. Should I remove the boards and use Deoxit to clean all the contacts? If so, which boards should I do (if not all of them)?

Thanks in advance for any and all help.

[radiotvnut]

This is a common problem on those sets. Remove the modules, clean, and resolder the connections on the module. On the video output module, resolder the resistor pack and video output transistors. The luminance module will also have a resistor pack that needs to be resoldered.

[zenithfan1]

Ditto on what Bryan says

[TinCanAlley]

Originally Posted by radiotvnut

This is a common problem on those sets. Remove the modules, clean, and resolder the connections on the module. On the video output module, resolder the resistor pack and video output transistors. The luminance module will also have a resistor pack that needs to be resoldered.

When you say resolder the connections, do you mean all of the components on each board? Also, do I remove the old solder or just reheat it and let it cool?

The video ouput module is about 6 months old, but I guess sitting around for 30 years could have caused issues with the solder points.

Another quick question (I hope)... How much is involved with correcting the overscan? I lose about 1 1/2" or more on all sides and think this is a bit too much. That seems a bit much for a 19" set, but I could be wrong.

Thanks!

[zenithfan1]

I would reflow the solder on the boards suspect of trouble and go from there. Only add some solder if it's necessary. Sometimes the problem is the pins the module plugs into and that bad connection causes problems like you have. Be sure to clean them with some de-oxit, plus the sockets on the modules they make contact with. I really don't know an easy fix for the overscan, it's a common thing on older tvs, it allows some movement or shrinking of the picture due to voltage changes and parts drifting. People complain more about underscan, I think that's why they did it. Less service calls I guess.

[old_coot88]

Originally Posted by TinCanAlley

Howdy!
....The other issues is with either the brightness or contrast. I'll be watching and all of a sudden the picture goes to a negative looking image of just blues and reds and very dark. There are no whites or bright colors. If there is white text on the screen, you can't see it. I have to tap on the set to get it back. .

Try tapping gently on the CRT neck with something like a screwdriver handle. What you describe sounds like an intermittent heater-cathode short in the jug. Bill(oc)

[N9ZQA]

I had the same problem on my 25KC45, and like Bryan said, it turned out to be the resistor pack on the luma module. Resoldered the pins which were obviously cracked, and touched up a couple questionable ones, and it's been behaving well since. I've still got an intermittent slight contrast dropout, caused by a dirty pot on the IF subchassis, but haven't bothered to pull the set apart to get at it just yet.

The biggest problem on those sets is the module pins - if you remove the modules, clean the contacts and use a straight pin to add a little tension to the contacts on the modules (there's a couple fingers which point inwards to contact the chassis pins). I used a pencil eraser and contact cleaner to clean the chassis pins. You'll probably wind up breaking a couple of the little blue tabs; you want to keep as many of them as possible, since they are what holds the modules in, other than the tension of the contacts.

Good luck!

-Jim

[TinCanAlley]

Well I know what I'll be doing tomorrow. I think I'll do it one board at a time by first checking all the solder points and then cleaning all the contacts.

Just one more question about the modules. How are they removed? Do I just pull on them?

Thanks!

[radiotvnut]

There should be some little plastic retaining clips on the corners that you'll have to release.

[TinCanAlley]

Well I pulled the boards and check all the solder points. Seems for the past 32 years the luma module's resistor pack had the end three legs not soldered. Under close inspection, the end three showed no solder and light coming through around the legs on the back side of the board. I soldered them and cleaned all the contacts on all the boards with Deoxit.

So far, so good! No changes in tint and the contrast doesn't drop when tapping on the set.

Thanks for all the assistance and look for my new post on another issue.

[TinCanAlley]

Okay, I spoke too soon. The loss of brightness/contrast is gone, but the purple tint is still happening.

I found that watching a B&W movie shows it best. Although, now I see that the purple tint remains about 90% of the time with the remaining 10% being bright purple periods and periods of no purple tint. I've attached 4 pics showing the tint jumping in and out of a scene. My camera had a bit of an issue trying to capture the images, but the pics with the lack of purple are true B&W with no color tinting. I've also added a pic of the video output board.

I think this problem might be due to the video output board. It is an NOS replacement and maybe something is not set correctly on it (G2)? I don't think it's the tube as it tested good a few months ago, but I guess things could have changed. If a color gun was acting up, wouldn't it change the colors all over the screen and not just add a purple tint?

Anyway, got one issue solved and one to go.

Thanks

[TinCanAlley]

Well I found a section in the repair manual about black & white tracking adjustment. I followed the instructions and wound up increasing the green (G2) control and that removed the constant purple tint. I still get the occasional fluctuation, but it is not as noticable.

Anyway, thanks for the assistance.

[jstout66]

You have one of the LAST CC2's with the first inline tri-focus tube. They came out the same year System 3's were introduced, and I think Zenith was clearing out the parts department. I had one new but shortly upgraded to a 19" System 3 with Space Phone. (my Uncle was a Zenith dealer)

[TinCanAlley]

Originally Posted by jstout66

You have one of the LAST CC2's with the first inline tri-focus tube. They came out the same year System 3's were introduced, and I think Zenith was clearing out the parts department. I had one new but shortly upgraded to a 19" System 3 with Space Phone. (my Uncle was a Zenith dealer)

I'd really love to get my hands on another model (lager as well), but here in So Cal they're pretty hard to find. People here either hold on to things until they fall apart, or they trash them for the newest thing to come along. Don't seem many in the thrift stores, either.

I'm attaching an image from the service manual that has pictures of some of the TVs covered. The one I really would like is the J2540X.

[ventosa]

here is the link where byou can find a zenith J2540x tv

http://toronto.kijiji.ca/c-buy-and-s...AdIdZ408396817