RCA CTC-120 No Color - Videokarma.org TV - Video

bgadow · #1 04-15-2013, 09:40 PM

I got a call over the weekend from a guy in the neighborhood; him & his brother ran the cub scout pack back when I was a kid. His brother, a career tv repairman for Sears, passed away recently. He had been asking around & was told I worked on old radios; might I be able to fix a tv with tubes? Sure, I was skeptical that he was really using a tube-chassis set but I kinda envisioned his brother nursing some old Warwick-built Silvertone all these years. Sure, I'll stop out and take a look.

Of course, it was solid state. He was really surprised when I showed him the chassis. Rca from '85, CTC-120, pushbutton/no-remote. It had intermittent color and then totally lost it. They want to keep it as they always wanted a console, and this one had belonged to a close relative who passed away. A dumb move on my part was forgetting to play with the color pot on the front before yanking the chassis. Well, I'll pretend they tried it! Tapping the crystal did nothing nor did a slight twiddle of the adjacent coil. Question: should I replace anything besides the crystal at this time? Anybody recall the common failure mode? Thanks in advance!

sampson159 · #2 04-16-2013, 08:20 AM

i remember a connector on these sets that would cause the color to flicker and leave intermittently on this set.i left the repair business around that time and there were a few of those in the shop with that issue.also,there is a control buried that is slightly misadjusted.ever so slight,we turned it and color popped right in and locked.i didnt care for the rca s of that era.too many silly problems

Zenith26kc20 · #3 04-16-2013, 08:28 AM

Look for a ceramic trimmer capacitor that stands upright near the color IC. It has a brass or silver screw to adjust. It gets out of adjustment (drifts) and may need a few turns either way to restore color.
We did hundreds of em.

andy · #4 04-16-2013, 09:47 AM

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bgadow · #5 04-16-2013, 02:16 PM

Thanks, guys! That was the trimmer I twiddled, but only about a 1/4 turn each way since I didn't want to throw it too far off kilter. It looks to be solid. I blew the chassis off good (covered in black dust, they're heavy smokers.) Maybe Wednesday I'll carry it over there along with a spare crystal and some spray cleaner. My only fear is getting everything plugged back in right-I should have just left it in place. Will update.

bgadow · #6 04-17-2013, 11:51 AM

Another one saved! Perfect advice. I had to crank the adjustment in about 2 turns, that's all it took. They were very pleased...told them if it ever goes out again, call me and I'll give it another crank!

bgadow · #7 04-21-2013, 09:35 PM

Got a call tonight, the set owner said now the TV keeps turning off by itself. Well, drats! This has, I'm pretty sure, an old fashioned "real" power switch. Maybe it will just be a bad connection-anybody run into anything odd on this chassis?

jstout66 · #8 04-22-2013, 06:15 AM

Bryan,
I am NOT "with it" at all on newer stuff, but.. I had a buddy I gave one of those 27" Colortrac 2000 consoles to, and it would randomly shut off. That set was a remote set, but I know they had some power supply issue. Do you think that might be the case with yours? I know the chassis in that was a tad newer, but I don't think by much.

bgadow · #9 04-22-2013, 09:39 AM

I did have one a little newer, later 80s, that would only turn on intermittently. It had a different chassis layout and a momentary style power switch. In that case it was a bad cap; it wouldn't turn itself off, though. Guess I'll ride out there today and see if I can narrow it down.

sampson159 · #10 04-22-2013, 12:56 PM

look for bad joints on the tuner module.we had several that would shut off intermittently.

bgadow · #11 04-23-2013, 01:35 PM

Looked at it today, not far from the degaussing thermistor there is a pair of wirewround resistors, one of which is pretty charred. Even the slightest touch in that area will turn it on/off. I touched up the joints around there but suspect an internal break in that one resistor. I'll try changing it tomorrow. That thermistor is shot, too. As usual, when I tried soldering the loose lead off one side the whole thing crumbled. Not sure if I'll worry about that right now.

radiotvnut · #12 04-23-2013, 02:17 PM

I've also seen bad connections around the flyback and horizontal driver transformer that causes these to shutdown.

bgadow · #13 04-24-2013, 10:10 PM

That resistor was a rabbit trail. I found that touching it ANYWHERE on the chassis would cause it cut out. Taking radiotvnut's advice, I looked in the flyback area. Found a very obvious bad solder joint about 1" inboard from the fly, didn't even bother checking to see what component it was. Rock solid now.