Yamaha A-520 Repair

I purchased my old Yamaha integrated amp new way back in the mid eighties. It was a faithful workhorse powering my old Klipsch KG4s to irresponsible volume levels for many years. Fast forward to today and my amp has been sitting idle for a few years because of the left channel intermittently dropping out. I assumed it was toast. Recently I've become obsessed with putting together a really great sounding system for the den. Since my wife tells me that my budget for the project is $0.00, I started thinking about my old amp again. While dorking around with it, I noticed that the balance knob seems in some way related to the channel going out. I sprayed it with contact cleaner (as best I could) and it got a bit better. When the channel is down, I can apply sideways pressure to the knob and get it back. All this makes me think that all this time it's just been the balance knob that's the problem.

Obviously, twiddling the knob every time the channel drops isn't much of a solution, so what are my options? Is my diagnosis correct? Do I just need to do a better job with the cleaner? Would the part be available 25+ years after manufacture? Would a standard pot work or is it more complicated than that?

I look forward to your thoughts!

mb

I would try to find a electronics service place in your area that specializes in older audio or pro sound applications because they deal with this kind of thing all the time. If you really feel up to it you could take it apart and replace the balance attenuator yourself because most likely it is a standard balance attenuator that a lot of units had in the day it was made and probably could be found or something that will work could be. But the main thing is that if you are not comfortable with soldiering and taking electronics apart then let someone else that specialize in it do it because you might do more harm than good. I mean you could try to clean it better and take a good look at it and make sure all the contacts are ok but to me it sounds like you would be better to replace the attenuator if you want to get more years of good service out of it. just my two cents

Given that the minimum charge to even look at the thing would be $50, plus whatever they end up doing to it, it begs the question "is it worth it?". Craigslist is full of <$100 receivers. Is an old Yamaha (75wpc) integrated going to sound better than some craigslist find?

Btw, I can probably wield a soldering iron well enough to do the job, not that I'm an expert or anything.

mb

Well if theres nothing to loose really I would give it a shot. The worst that could happen is that you screw up and screwed up unit anyway. And I am sure you can find a balance component that would work with the Yamaha. If that does not work I would hit up Audiogon, craiglist or whatever used electronics you can get since used stereo receivers are cheap as hell and you can usually find a good unit for cheap to do what you are wanting to do.

I would see if you can bypass the balance knob.

After messing around with it a little more, I found that it has something to do with the face plate. If press on it or depress a button, it moves a bit and makes the channel come in or out. Manipulating the balance knob was just basically doing the same thing. I suspect either a short or a bad ground.

It's gotta be a short

Bizzare. It's in the kid playroom/den and I've been using it anyway because once it gets warmed up and you dork around with it a bit, the channel comes back. The odd part is after increasing it's usage (it basically sat for a few years), the problem has essentially gone away. It must be happy it's back in the game.

You need to open it up so you can access the entire pot. With cleaner (Deoxit) spray the hell out of it and work it back and forth at least 30 - 50 times. It's a dirty pot for sure, you are experiencing poor connection due to grime and dirt. When you push the frame it's undoubtedly forcing a connection through the muck. Simple repair...enjoy.