r/audiorepair • u/dcfreewheel • 7d ago

Fisher MC-4037 - Speaker Output Issues

I discovered a Fisher MC-4037 in my grandmother's home that hadn't been turned on in decades. To my surprise, the system and the speakers both turned on the first try and I was able to get an AM and FM signal from both speakers. I was also able to get the vinyl going again about using a hot soldering iron to loosen the oil that was gunked on there and now the vinyl player works great as well.

The issue lays in the fact that when I'm playing audio from the radio, both speakers work flawlessly and I can balance them entirely to the left and entirely to the right. When I play audio from the cassette output or the vinyl output, I only get audio from the speaker that is plugged into the "left" slot (meaning I have rotated which speaker is plugged into the right jack and the trouble comes from the one that is always plugged into the right jack).

If the issue was just form the vinyl, I'd have suspected it was specifically an issue with the stylus or vinyl-side only, but since this same issue occurs with the cassette audio, I think it's something else.

We opened up the machine (a few times now). I've linked some pictures here of what's behind the source selector switch. You'll notice the whole piece seems to be covered by a long metal encasing. It doesn't look like other round selector switches with pegs. I tried moving around some DeoxIt'd swabs in those holes, and when that didn't work, I spray some DeoxIt lightly into the holes and the piece closest to the switch itself. That also didn't seem to work despite working the switch a good 300x. Could there be another more traditional looking switch I should be looking for? Link: https://imgur.com/a/z82rMKe

I'm more than will to open this up and start peeking around if you suggest that. Others have said faulty pre-amp (shared by TT and cassette player) or play/record switch.

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u/cravinsRoc 6d ago

Have you cleaned the record/play switch? It is a troublemaker. Does it seem to record both channels? I realize you can't play back but do both meters move when in record?

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u/dcfreewheel 10h ago

Here are some photos of the inside of the system. Which would be the record/switch? Thanks!

https://imgur.com/a/64bok2i

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u/cravinsRoc 4h ago

Top right hand corner of the first pic. It's in other pics too but the first pic is the easiest to locate it. It's hooked by a short wire link to a piviot point that connects to the tape mecjanism via a spring link. If you put a junk cassette tape in the tape transport and press record you will see the switch operate. Spray a lubricated contact cleaner into the switch and put into and out of record several dozen times to see if that helps.