View Full Version : Zenith 25MC36 color/sound problems

04-03-2017, 04:10 PM
When i got this zenith home and fired it up, it had no sound or color. I got this set in a trade from dave and he told me the color had gone out while he still had it. I told dave about the no sound problem and he said that the sound was working before I took it home. I checked the audio output tube and tested a-ok. So any help with the two problems will be appreciated.

04-03-2017, 07:04 PM
About the no color, I might try taking the chassis out of the set, and trying to do a visual inspection of the tube sockets. I remember before I changed the 6JH8's, the color was working, but with the new ones, there was no R-Y or B-Y. When I put the old tubes back in, one of the demodulators was working, I don't remember which one. About the no sound issue, I don't know what's going on. Maybe inspect the wires coming from the audio output transformer?

04-03-2017, 08:18 PM
Going to sound strange, but my 25MC33 chassis has had a couple of intermittants caused by connections (solder tabs) on the tube sockets. The filaments go out when the connection has problems. I looked over all connections on the demod tubes and found problems. Also, lightly pull on the wires going to the tube sockets. The soldering zenith used sometimes missed a connection and over the years, the connection oxidized and the tube went out.
Do you hear anything with the volume control at maximum? Also, check the plate resistor on the burst tube. The original will fail if the tube gets gassy.

04-03-2017, 09:11 PM
Me and my stupid self didn't check the dern speaker plugs, so i did and found that the speakers were UNPLUGGED!

04-07-2017, 07:41 AM
Well after some tinkering, i got decent color, green is very dominant while red is not really there.

04-08-2017, 08:59 AM
I have a *BUNCH* of PF reporter articles on the 25MC36. Since I this same chassis in a combo set, Im motivated to research. Ill scan and post them here. This thread title makes a great search term.