Could a dirty Tape Mon switch cause static in only one channel? Fisher 400

I assume it could, but don't know enough to be sure. But I had an intermittent static coming from my left channel for months. And months and months. I tried many times to narrow it down but never could.

A couple days ago I tried using the Tape Mon input instead of the Aux which I always use. Flipping the Tape Mon switch I heard static, the same static I'd been Moby Dicking for months! After cleaning the switch the static is yet to return. And I think the sound is in general much better. It's more full and less thin.

Could it have been that simple?

Yup.

Step #1: Clean all switches, controls, tube sockets & pins.

I guess I was penny wise and pound foolish saving time skipping Step #1.

Thank you.

True story:

Scene: An audio repair bench in the early 1980s. A young wannabe technician has a tube-type receiver on the repair bench. Good brand; if it were in good condition today it would command a healthy price. He's trying to track down a gritty distortion in it. He's adjusted bias. No luck. Adjust driver stage balance. Still distorting. He's taken a new set of 7591 tubes from the shelf and tried them. That didn't fix it; so he put the new ones back and the old ones back in. Driver tubes? More new tubes off the shelf. Nope. Put away new tubes, put back the old ones. Maybe he should change the coupling capacitors (today, he'd make a great Audiokarma forum participant: "RECAP, RECAP, RECAP" when it was totally unnecessary); he asks what I think.

By this time I want him to get to work on something else, so I go over to his bench, squirt some contact cleaner into the tape monitor switch, slide it back and forth, and walk away.

FIXED...

True story #2:

A few years ago I saw an eBay ad for a Fisher 400. Cosmetics looked very good but the listing text said: "One channel is dead". Heck, I love to bottom fish, so I put in a low snipe and forgot about it. Got it for $122.

It arrived well packed and undamaged. Looked even better close up. So I hooked up some speakers and fired it up. One channel dead. Turned it off, did a little click-click-click-click on all the switches, turned it back on...

Full sound in both channels. :thmbsp:

Anything that switches both channels can futz up one of them. Another frequent offender is the mono-stereo switch.

In my case it turned out to be a very dirty volume pot.
Despite the gallons of Deoxit, I ended up taking it apart and cleaning it.
Problem disappeared.

Thanks for the stories, guys, makes me feel a little better.

Last night armed with a new can of Deoxit I removed all tubes, took off the bottom cover and got to every switch and rotary I could. I cleaned the tube pins, the sockets, the RCA jacks and then played with all the switches like a baby chimpanzee. Fired her back up and Ms. 400 sounds better than ever!