1995 Fender “Evil Twin” channel switching

[Opry Audio]

I have a recently purchased “evil twin” for an extremely low price due to it being possessed by spirits with the will to switch channels instantly and randomly..

Joking aside, it switches when I chopstick the ribbon cable going to the tone and volume controls :)

It seems near impossible that something has shorted in the ribbon cable itself. Should I consider replacing the connector? I bet this is a common issue

[tubenit]

I don't think those ribbon cables are very sturdy at all.  And it would not surprise me one iota if there is a short in it.  Not saying that's "the" problem.

Why do you think it's "near impossible" to have a short in the ribbon cable?

with respect, Tubenit

[AmberB]

If it's been played a lot, the vibration "could" possibly cause a break in one of the wires in the cable that causes intermittent problems such as the problem in your amp. 
Who knows, it's one possibility.  There's also the possibility of a cold solder joint on the board...

[glass54]

Hi Opry,
If it's the 94 Twin, I doubt its the Ribbon Cable. Assuming it based on the PR266 PCB, its more likely to be dry joints.
Look at R106, R107 in PS, also J3, J4 and J8, J9 Sockets as well as J7 footswitch Socket. All these gave trouble ie fractures in PCB.
Unfortunately, the PCBs have to be removed to do a thorough rehab on this amp.
R138 also gave trouble with crackling (1M best replaced with a MF type.)
There were a number of Fender "Tech Notes" made in 1995 to fix a few Gremlins 
Kind Regards
Mirek

[Opry Audio]

Thanks for the input y’all, I think it is possible that there’s a short in the ribbon cable, but I don’t find it often. At least for all the work I do on amps with ribbon cables.

I’m gonna pull up the board tomorrow for a look see.. it’s beyond a pain. Not my favorite amp to work on at all. In fact, I think they suck, but I would like to pass this on to someone else in less sucky condition 

[Opry Audio]

If it wasn’t so dang heavy I would build another amp into it. I got it for nothing.

[Opry Audio]

Alright, the channel switching issue is resolved. The amp is working great now except for the reverb circuit. It’s really noisy, and weak, and the mix control produces a lot of unwanted frequencies. I need to get a scope on it, but I’ve never heard this kind of thing before. I see there’s a fet somewhere in the reverb circuit so I may look there. It doesn’t sound like a bad tank or tube