Who can help with this Chromacolor 2?

[Carmine]

The person who is in charge of the displays at the WP Chrysler museum (where my '59 Zenith SC was displayed) sent me the following e-mail a while back:

My wife is very active in the Farmington Players doing community theater, she has appeared in plays there and is currently directing one, Neil Simon's "Part two". The play takes place in the late 70s and the stage setting is two different New York apartments. Would it be possible for me/the Farmington players to borrow those two sets as functional set dressing pieces for this play? We would like to use them by hooking them up to a DVD player and playing bits of period shows like "Three's company" and "Love Boat", perhaps an old news broadcast at certain parts of the play. we would come get them and return them and treat them with the upmost in care and respect. I will personally see to it that they are covered with furniture pads after each show. We would give you credit in the program and some complimentary tickets to the show.

I want to help him out. I think its cool that somebody finally cares about authenticity!

But here is my problem... The curved Zenith (panarama) has a problem where the tuner "drifts". You get it tuned in perfect, then it slowly de-tunes itself. Other times, the channel that came in perfect is suddenly full of snow.

I removed the IF module and re-soldered all the female contact points after finding one with a micro-crack in the solder. I did the chroma module (because I noticed some color-shifting) and the board with AGC circuits (forgot the name) for good measure. This didn't help the tuner problem.



Captain Moody says I need to re-solder the actual tuner board on the backside of the flip-down chassis. However, this isn't a plug-in module, so I'm not exactly sure what needs to be re-soldered. A close inspection doesn't reveal any cracks.



I think the problem is in the varactor part of the tuner, because it reacts to the slightest movement. Are there any typical problems with these?



On the positive side, I did spend some time touching up screen controls and other adjustments. It does get a hell of a nice picture when it works properly..

I actually think it might do OK with a strong source like a DVD player, but I don't want it giving any problems during the play.

[radiotvnut]

The individual pots for adjusting each channel may be dirty. Does it drift on both VHF and UHF or just VHF only? I notice that set has a seperate VHF and UHF tuner and there could be a problem with the tuner; however, I'm leaning more towards the actual selector assembly itself. About the only luck I've had repairing these is taking it apart enough to clean the little pots for tuning each channel. There is a sticker on there warning against the use of contact cleaner on the selector switch assembly. I guess there's some plastic in there that could be damaged; so, make sure whatever cleaner you use is safe on plastic. You might also check the connections where the selector assembly plugs into the chassis.

[Carmine]

It is actually just a one knob design. Looks like i will have to take the tuner apart.

[3Guncolor]

It sounds to me that it’s the tuner control panel. The panel behind the tuning knob. Either the selector switch or the pots could be dirty. It’s a good idea to stay out of the tuner unless you are sure there is a bad connection inside. Also check all the connections between the tuners and the control panel.

[andy]

I had a late model 19" Chromacolor II with the single tuning knob when I was a kid that would drift with warm up. I never did completely solve the problem. A different tuner helped, but it didn't cure it. I think the problem was in the tuner because when I ran it with the tuner open (ready to hit it with freeze spray) it didn't drift. Are there any electolytics in the tuner?

I just found a compromise fine tuning adjustment that allowed it to stay locked on to the cable box output.

[Carmine]

Ok, little update for you all...

I did disassemble the tuner and gave the board and pots a spray-down with brake cleaner (no residue)... Sorry purists, I have more car stuff than TV stuff.

You actually have to take it apart pretty far to get down to the circuit board.



When I sprayed it down, plenty of brown goo rolled off the boards. I can only assume Nicotine, although the rest of the set isn't discolored.

Once it went back together, I was able to get a nice solid picture on it.



Oh happy day.