Zenith 25DC56 color problem

[DaveWM]

lately when I turn on my avanti, the pic will come in B&W. adj the fine tuning does not effect nor do other adjustments.

if I change the channel it will sometimes comes on right away, otherwise it may take a fey trys but it always is fine within 30 sec, and is good to go from then on.

I am assuming I have a chroma issue, perhaps a cap on a board starting to go?

[DaveWM]

I suppose the chaning of channels has nothing to do with it, so I will try just turning on and waiting.

[kx250rider]

Many things to do on that:

1) Spray-clean the Chromatic switch and color/hue controls

2) Remove the color modules, and carefully squeeze the contact sockets a little tighter, put some tuner lube on a Q-tip and wipe the chassis contacts before reinstalling the modules

3) Re-solder all (ALL!!!) of the ground lugs on all of the wire terminal strips on the chassis. Those are the #1 cause of headaches in that chassis. Some of them have a ground lug in the middle, as well as at each end. Use a powerful iron or a soldering gun for that job.

4) Align the color oscillator pot; Basic procedure is throw the switch next to the color oscillator module, and turn the pot to get the fewest color bars, then return the switch. NOTE: It's a trim pot; not one of the coils. Be sure to do this with the metal cover installed, or the cover will detune the color when you put it back on after the job. There are holes in the cover for a plastic flat-blade diddlestick.


Charles