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My MC 2205 Amplifier is smoking???

Hello Friends, I am new here because of an inheritance of a Vintage McIntosh System. I will not go to deep down that story again as I already introduced myself. The reason for this post is I received my RCA and Speaker wiring today and couldn't wait to give this baby a test drive to asses the needs.

After some tinkering I was able to get a station to come in clear and a decent volume to come out the speakers.

The good news is, the speakers are worth salvaging with maybe a rebuild and a clean up. THe bad news is the Amplifier is producing smoke. I removed from the Casing, and dusted a bit more, I am hoping it is just because it was sitting for 15+ years.

 

Any thoughts???

 

PS. I am in SO CAL if any one knows a good tech to take on some of this work. 

basicname
2psyop's avatar
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2psyop
1,600 posts
 

I don't think the word "smoke" and the word "amplifier" should be used in the same sentence. It's a bad combination. Good luck.

basicname OP
3 posts
 

Thanks for the input, I am hoping it was a combination of some lingering dust and maybe the capacitor warming up. I am going to give it another run after some detailed cleaning today.

 

The funny thing is that nothing was hot in the amp. I could not identify where the smoke was coming from....

dekay's avatar
dekay
5,607 posts
 

Check out Audiocraftsman (Mike Zucarro) in San Diego.

 

DeKay

bigkidz
3,388 posts
 

Contact Johnson Wu  he is an Agon member  he is very good at repair work and is in CA.  If you cannot locate him shoot me a PM

 

 

gs5556
1,235 posts
 

Nothing in an amp would cause anything to heat up to the point where it smokes. You may see 70 Celsius in spots, which is nowhere near to start smoking things like bits of paper or dead bugs.

Are you seeing a wisp of smoke or is it like a burning cigar? Things that overheat or fail will produce a wisp of smoke, cigar-like smoke is usually followed by an acrid smell that indicates burning electrolytic solution or insulation.

On an old amp, I would first suspect a failing film capacitor if it is a wisp of smoke. If you can see the power supply, follow the secondary wires of the transformer to the circuit board. These wires are usually red (red/white usually is the center tap to ground) and are fatter than the primary 120V wires, which are colored black, green or white/black or red/white. Between the secondary red wires on the pc board, there may be a mylar capacitor for EMI rejection. See if that capacitor is bulging, cracked, or soot black. This is fairly common, especially the gold Rifa PMY caps.

Other than that, you can use a bright light and inspect the circuit boards to see if you can see a burned resistor. All good resistors have colored bands and a damaged one will appear burned. Easy to spot. If that is the case, then the amp needs a diagnostic because resistors do not fail on their own, only a very high current causes that, which almost always comes from somewhere else such as a shorted diode or transistor.

I wouldn't even plug it into the wall until it's serviced. 

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