My Brand New CTC-7! - Page 36 - Videokarma.org TV - Video

SwizzyMan · #**526** 08-26-2015, 05:55 PM

OK resoldered pin 3 and everything is back to normal. But is 178ma OK for the cathode current though? Do any adjustments need to be made?

tvcollector · #**527** 08-26-2015, 08:50 PM

I think 178ma is fine, most of the 60s sets are usually around the 200 mark or below.. after 210 or 215, then it gets into the high range and will cook the flyback eventually.. Yours only spikes up for seconds upon turning on, and I think that's normal..

SwizzyMan · #**528** 08-26-2015, 09:13 PM

Yet another issue. Put the chassis back in (which was hell) and now I am having signal problems. I'm getting the weird tuning beeps and squeals and everything is covered by a shade of green.

Phil Nelson · #**529** 08-27-2015, 12:05 AM

It worked beautifully not long ago. Look for obvious stuff first. Wiggle tubes, starting with the tuner and working forward along the signal chain through the IF section, and so on. Look for wires you might have knocked loose when removing or reinstalling the chassis, etc.

Phil Nelson

SwizzyMan · #**530** 08-27-2015, 06:27 AM

OK well the 6AW8A on the agc board is not even glowing I wiggled it around a bunch, still nothing tried swapping with a known good tube still nothing. Could I have broken the socket? And is that tube the reason for the bad signal and green tint to everything?

Zenith26kc20 · #**531** 08-27-2015, 10:45 AM

The boards on the RCA color run hot. If subbing the tube does not help, it may be the solder connections under the tube socket. If you do pull the chassis again, resolder the 6AQ5 vertical output socket pins. The 6AQ5 runs very hot and those connections can be troublesome. The strange thing is the 6AW8 is first video/AGC. I would think no picture if it is not lighting.

SwizzyMan · #**532** 08-27-2015, 02:21 PM

Going to clean the tuner and resolder the tube sockets. Let's hope this goes well!

SwizzyMan · #**533** 08-27-2015, 03:16 PM

Resoldered all the pins on the 6AW8A socket and checked for any visible damage still no filament glow checked the heater pin voltages with the dmm nothing at all.

Zenith26kc20 · #**534** 08-27-2015, 05:15 PM

You are going to have to trace the circuit foils and see where you are losing the 6 volts AC. Look at the grounds on the board. They can cause trouble.

SwizzyMan · #**535** 08-27-2015, 07:51 PM

Cant seem to trace it. The foils arent actually traced to another lead it is just a dot of solder. Should I just put in a new socket?

Electronic M · #**536** 08-27-2015, 08:45 PM

Quote:

Originally Posted by SwizzyMan

Cant seem to trace it. The foils arent actually traced to another lead it is just a dot of solder. Should I just put in a new socket?

Check the resistance between the top and bottom of the socket. If it checks open replace socket. If it tests like a wire then you are going to have to try harder to trace it since it ain't the socket if you have continuity.

Keep in mind that if you don't have 6.3VAC at the socket solder pads it won't work even if you change the socket. Also if one of the heater pads is supposed to be grounded and the trace or ground lug is bad that will kill your heaters too.

SwizzyMan · #**537** 08-27-2015, 09:25 PM

OK resistance is good on all pins so just going to have to see what the problem is. I did notice that on the other socket next to the problem socket the middle ground lug is there but on the problem socket it looks like it never had that middle ground lug even though a trace hole is there but has a thin layer of solder over it. Would this raise any red flags?

old_coot88 · #**538** 08-27-2015, 10:34 PM

OK here's a simplified sketch from the CTC-7 schematic.
There's a second tube on that board, a 12BY7. Is it lighting? (Assuming it is.) It'll have 6V on pins 4 and 5, which are tied together, with the center tap (pin 6) grounded.
There should be a long trace (or possibly a wire topside of the board) going over to the 6AW8, carrying 6V to pin 4. If 6V is absent, look for an open somewhere on that line.
-
If there is 6V on both pins 4 and 5, look for an open ground offa pin 5.

SwizzyMan · #**539** 08-28-2015, 05:59 AM

Hmm that is puzzling, I could have sworn I pulled another 6AW8A out of the 12BY7A socket. Could that have caused the loss of filament on the 6AW8A in the other socket? Then again, I'm pretty sure that there was always a 6AW8A in the 12BY7A socket and I know that at one point the problem tube did glow. Will go and pick up a 12BY7A today just in case and do some investigating on that board.

SwizzyMan · #**540** 08-28-2015, 06:09 AM

Was able to dig up a 12BY7A. The 12BY7 glows but still no 6AW8A glowing. Will investigate more later today like I said.