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McIntosh 402 amp channel stopped working

Howdy folks-

McIntosh 402 amp

Am having trouble with my left channel not working, thought it was a short in my phono pre. I would adjust the power cable on the phono pre a little and it would work, then not work, but mostly work. Got a new JLTi phono pre today from Australia and same thing, left channel won't work. Hmmmmmmm

Started trouble shooting. Exchanged cables, sources and even a different receiver, different phono pre, same situation. Switched speaker wire, same issue. Odd thing is when running through my McIntosh preamp in mono, both channels work. 

At the moment, big Mac 402 running the mains through the Anthem processor, same issue, no left channel. Thoughts? 
I'll contact the local HiFi guys here in Miami to see if they'll look at it. I don't want to send it off to mac head quarters!
128x128knollbrent
knollbrent's avatar
knollbrent OP
314 posts
 
So I took the 402 into a local shop that is McIntosh tech certified and he fixed my amp and my Aloia CDP. Got the amp home and the left channel is still not working. Switched the IC's around going to the pre and discovered it was a faulty cable according to him. I through in another cable and it worked!

But, it's happening again. Same problem as before, left channel is not working. Could it have something to do with my preamp???


nitewulf
277 posts
 
it could just be oxidized connections, use deoxit on all rca inputs/outputs and speaker outputs terminals. 
miner42
698 posts
 
Have you tried switching L & R speaker cables on amp to see if problem switches channels?  Can you hook your CD player up directly to amp to eliminate a preamp issue?
knollbrent's avatar
knollbrent OP
314 posts
 
Yes, just hooked up cd and using the 402amp, I ran everything thru my Anthem receiver and the two channels work fine. It's the preamp. C2200 is at least 15 years old and the tubes have never been changed. 
knollbrent's avatar
knollbrent OP
314 posts
 
So now I have a second pair of IC's go bad within a week. It must be the preamp that's doing that?
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