Zenith 1979 Chromacolor II - No color

[Palinurus]

Originally Posted by JohnCT

There are several suffixs that will sub the -02. I *think* any sub that is even number will work, but I'm not positive. There are people I can call that will likely remember.

In the meantime, some of this is coming back to me. Check the 24V regulator carefully for output. The regulator is a TO-220 mounted on the front of the chassis near the breaker. It has to be exactly 24v on the emitter.

Also, there are some electrolytics in the 24V feed on the back of the chassis that cause havoc. These are radials and are physically large. Check or just replace any of them.

Lastly, I recall a problem with an open coil causing loss of 24V to the chroma module. I'm pretty sure it's terminal W9.

And again, pull the ICs and clean the pins and reinstall - that fixed most of them. And I do believe that all versions of the -86 used the same ICs, even if the boards didn't sub. There's an outside chance I may have one. If I do, it's yours.

I'm pretty sure I still have the Zenith service data for those years. I'll check tomorrow when I get to work.

John

EDIT: if you need to replace a capacitor or inductor on the back of the chassis, do a clip and loop method. The components are soldered deep into the back of the module contacts, and the less stress put on the module contacts at this age, the better.

I had to ordered some solder wick to remove the two IC's from the module, so I'll have to set this project aside for a week or two. I did check the regulator and came up with 23.7 volts with a multi-meter. I don't know whether that's close enough to 24v but if cleaning the IC's doesn't work I'll change the capacitors as well. Are the IC's for these old TV sets hard to come by? If so, and you have a couple I'd be glad to cover the postage if you were to send them. Once again, thanks for all your help.

[JohnCT]

Originally Posted by Palinurus

I had to ordered some solder wick to remove the two IC's from the module, so I'll have to set this project aside for a week or two. I did check the regulator and came up with 23.7 volts with a multi-meter.

Close enough.

...but if cleaning the IC's doesn't work I'll change the capacitors as well. Are the IC's for these old TV sets hard to come by? If so, and you have a couple I'd be glad to cover the postage if you were to send them. Once again, thanks for all your help.

If your ICs are soldered in, then cleaning won't help. That advice is for those 86 boards that use those crappy individual pins for sockets. I think the K series might have been the last vertical chassis Zenith, and later ones eliminated the sockets entirely (constant socket issues), so if they're soldered in, the oxidized pins are not an issue.

Look for 24v on the 86 board directly, I believe it was W9 IIRC, but if not, there is definitely 24V on one of the pins. If it's not there, there's an open inductor on the back of the chassis.

I may have a board, and others here will have a complete board as well. These were not that much trouble where they would be in big demand. Most vertical chassis Zeniths had contact problems with the modules, not the modules themselves.

John