CTC10 Finally a failure - Videokarma.org TV - Video

Tom S · #1 01-19-2015, 07:33 PM

Hey guys, Anyone have any common failures in the Horiz Osc circuits? Watching my CTC10 and Freq went way off all the sudden. Have to get more of my equipment home and diag this thing. I tried the OSC 6FQ7 from my CTC11. Same thing. Any help is appreciated.

Username1 · #2 01-19-2015, 07:47 PM

Is it way off frequency, or is it incomplete scans....? Cap in the yoke...?
Shorted coil in osc. circuit, or cap going bad....

.

Electronic M · #3 01-19-2015, 11:18 PM

Is it recapped? If not then the osc. capacitor would be my first suspect. Bad solder joints on the osc. transformer could also be the issue.

dieseljeep · #4 01-20-2015, 09:50 AM

Quote:

Originally Posted by Electronic M

Is it recapped? If not then the osc. capacitor would be my first suspect. Bad solder joints on the osc. transformer could also be the issue.

IIRC, the set still uses a form of Synchroguide circuit. The cap across the coil, .01 mfd @ 600v could be the problem.
The set's old enough to still use some paper caps.

miniman82 · #5 01-20-2015, 05:36 AM

That's way off frequency, first thing I'd check is that the osc coil hasn't suddenly shorted or that the hold control didn't open up (check tin whiskers as well).

dtvmcdonald · #6 01-20-2015, 09:56 AM

That's similar to earlier nightmare RCA horizontal circuits. Its a
nightmare due to obnoxiously complicated feedback. I had terrible
problems in my CT-100, fixed only by replacing all caps and resistors
in the circuit. All replaced parts tested good, at least at room temp and
zero volts. Check for obvious bad parts. If there are none, try
a full recap and re-resistor with overrated resistors.

DaveWM · #7 01-20-2015, 12:19 PM

I would try grounding the AFC circuit pin 2 of the 6CG7 to make sure its not a defect from the phase detector diodes, then check the .01 across the hold coil and the 390pf of pin 7 would be where I would start.

Pete Deksnis · #8 01-20-2015, 05:38 PM

Quote:

Originally Posted by dtvmcdonald

I had terrible problems in my CT-100, fixed only by replacing all caps and resistors in the circuit.

Had the same CT-100 problem about 6-1/2 years ago. Got tired of troubleshooting, so rebuilt the entire horiz osc circuit. Never did discover exactly what the problem was. It worked fine after the rebuild. Looks pretty with all those new modern parts!

Pete

Tom S · #9 01-20-2015, 06:36 PM

shorting pin 2 on osc does bring it within limit. No sync of course but the squeal is gone too.. All volts on plates are high when no short. Closer when pin 2 shorted out. Set has been recapped too.

DaveWM · #10 01-20-2015, 06:38 PM

check those diodes out

Tom S · #11 01-21-2015, 03:35 PM

Well I thought I got every cap. Guess I missed one.. Dammit. I put a terminal strip and left the old caps in place. All unwired of course. Missed 2 sections. 80@ 450 and 160@450. Plus I took out the damm B+ fuse and I really don't know how. Stole the one out of my CTC 11 it was 3 and 2/10 amp. Set played for a short time and it went too. But I didn't unhook old cap's. Just used my sub box. You can tell I've been out of it for a bit. Put cart before the horse. LOL. I'll change caps then try again. I hope all goes ok. I should always check power supplies first. AC can play some good tricks for sure.

Findm-Keepm · #12 02-03-2015, 11:15 AM

Quote:

Originally Posted by Tom S

Well I thought I got every cap. Guess I missed one.. Dammit. I put a terminal strip and left the old caps in place. All unwired of course. Missed 2 sections. 80@ 450 and 160@450. Plus I took out the damm B+ fuse and I really don't know how. Stole the one out of my CTC 11 it was 3 and 2/10 amp. Set played for a short time and it went too. But I didn't unhook old cap's. Just used my sub box. You can tell I've been out of it for a bit. Put cart before the horse. LOL. I'll change caps then try again. I hope all goes ok. I should always check power supplies first. AC can play some good tricks for sure.

Shouldn't the fuse be a 3.5A, not a 3.2A? All of my RCA lit for the CTC10 shows a 3.5A fuse.

Tom S · #13 02-03-2015, 11:31 AM

It is 3.5. Robbed the one out of my 11 that was lower. Now it also has 3.5 as the circuit breaker was bad and pryor owner had put in a fuse holder. Should put in a breaker again like it had.

Tom S · #14 02-03-2015, 11:32 AM

Also wish I could get the right Lit. I have sams copy and it's ok. Be good to have the right stuff so to speak. If anyone has it I'd buy a copy.

Findm-Keepm · #15 02-03-2015, 01:56 PM

Quote:

Originally Posted by Tom S

Also wish I could get the right Lit. I have sams copy and it's ok. Be good to have the right stuff so to speak. If anyone has it I'd buy a copy.

Look on eBay for the RCA field service guides - I have the 1955-1966 one, with all of the early color sets. It also has aa abbreviated parts list for each chassis.