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Lost a channel in my Dad's old Sansui

E

electricon

New Member
Howdy y'all,
I've had my Dad's Sansui 4000 since he passed away, when I was 11. Last year, after 20 years of constant use, I lost the left channel suddenly. I handed it off to a guy to give it to a guy to repair it, and after a very long wait I got it back from him. I had the same problem within a week. We repeated the process, and now we are in the same place again. This guy is giving my the runaround and I don't wanna deal with him any longer.

So, when I first powered it on, there was no left channel. When I turn it off, it sparks to life! With some jiggling of the power switch, it crackled back to life (and sounded so good!) for a couple LP sides, but now it is gone again. The left audio is there in a tinny and crackly fashion if I crank it, but that's about it. I get audio out of both speakers with MONO engaged, and I get the left channel if I engage the REVERSE switch. I have turned off to see if it will return to the same uncertain state.

My question for you all is, what steps can I take to diagnose the issue? I have perused the service manual and don't see any steps regarding these symptoms. I have no one in my town to take this beloved artifact on, considering the runaround I've already had. I've built a handful of guitar pedals and repaired some broken synthesizers, so I feel like I could fix what's wrong with it if I knew where to start or what to do. I have a multimeter and can solder/desolder very well. Can you tell me how to get this back to life? Thank you all for such a wonderful resource.
 
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Sounds like a dirty Switch. I would take off the Front and the top and bottom, and do all of them with DeOxit D-5, then follow up with DeOxit FADERLUBE F-5.

Most likely the problem is in one of the push button switches, as you get sound in Mono, but not stereo, plus fiddling with the switch causes it to cut in and out. this indicates a switch contact problem. IF you've never done a cleaning read this thread 1st!
"The Idiot's Guide to Using DeOxit (revisited)"


 
Thanks Larry! I'll give that a shot. I'll have to get some of the stuff tomorrow as I hear it's a miracle worker.
One thing that concerns me about the symptoms is that jiggling ceases to function after a while. It seems like there is some sort of rest that the amplifier has to take. I turned it off for an hour and was able to jiggle it back to life again, but only for less than minute before the Left channel tells to Do Not Resuscitate.
Thanks again!
 
Try cleaning the switches first and we'll move onto the next step.

Dont worry, plenty of sansui experts here to get her back to life again!
 
There is a level adjust pot on the back of the receiver. Try working it back and forth a few times. Clean it as well when you clean the other controls.

Rob
 
OMG it worked y'all! I was all ready to have to get soldering, but that really worked wonders. I'll have to try the Pioneer in my garage next! Thanks so much!!!!
 
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