I recently got an MCS 3543 (supposedly a rebadged Technics RS-M205) and I'm having this issue where the left channel records significantly louder than the right. When looking at the inputs through the built-in VU meters, they show as equal, but once recorded and played back, the left channel is always much louder than the right. I've looked at the board and its components, and I don't see any leaking capacitors or fried ICs/resistors. I'm honestly at a loss as to why this is happening
Without knowing your skill level, I'd start with the basics, clean the heads good with IPA or a good tape head cleaner. I'd DeOxit both rotory level knobs and finally I'd switch the back L + R both in and out to see if it really is just the right channel. I see it has dual mics in, I'd also DeOxit the MIC/Line switch really good, that's my first guess, switches like that that change inputs always seem to screw everything up when they get corroded.
I have a pretty good understanding of general electronics, just new to audio equipment. I used contact cleaner on all of the front switches and dials (bias select, dolby nr, and the input select) and also the trim pots for the recording current inside the deck. If I turn the right side potentiometer way up, it fixes the issue, but I don't really consider that a fix. I attached a picture of the heads, and it looks like there's some kind of smudge on the record head where the right channel would be. I haven't gotten to cleaning them yet, I will see if I can find some isopropyl around here. Playback of cassettes I've previously recorded (or prerecorded) are not affected at all, it seems that just the cassettes I record currently have this issue.
Since it appears to be a two head machine, using the same head for both playback and recording it seems unlikely to be the head. If you have an oscilloscope, you could trace the signal through both channels , looking for differences.
If I can find my multimeter, I'll give that a try. It turns out the both the erase head and the recording/play head were rather dirty, with some brown crud (maybe stuff from the tapes) on it, I'm going to hope that makes a difference.
I'll be damned, cleaning the heads was actually the fix! It's not perfect, the right channel is still very slightly lower than the left, but I can adjust the pot just a little to the right and everything's hunky dory. I appreciate everyone's help!
Nice, most Technics seem to be bullet proof, I rarely have anything other than maintanance issues with them.
