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Sansui AU-7900 cleaning switches and pots

J

jodyscott

New Member
Hello! I had my AU-7900 integrated amp serviced 3 years ago because of the sound changing from stereo to mono and back to stereo (I’m not sure how else to describe it). I also had the volume increase and decrease sporadically. This is happening again and what I have noticed is when I turn the “speakers” knob, it will often fix the issue when that knob is lightly turned halfway between selecting speaker A and speaker B. The same is happening when I toggle the tone and filter switches, as well as the loudness, muting and mode switches.

I’m hesitant to service / clean this amp myself. I understand there are some experts here that might be able to help. I’m very much a beginner and have no experience repairing electronics.

I have attached some photos and not sure if these might help diagnose an issue beyond what I’ve posted above.

Thank you very much in advance for any tips.
I’m running this amp into Wharfedale W90D speakers
 

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Welcome to the forum, from your description it sounds like you have dirty contacts in the switches and pots, you can buy some contact cleaner which is readily available in diy electronic and auto shops (and others) and spray lightly each of the controls and switches with it and then activate the switches/pots to get the solution throughout the mechanisms. let it sit for 10 minutes to dry and then you can power it up and see if it’s corrected your problem - avoid the power switch for this exercise if you feel like this is something you can do yourself, give it a go, there’s lots of videos on youtube that explain this which may help your understanding also. Best of luck with it lovely amplifier
 
Start by reading this thread.

The Idiot's Guide to Using DeOxit (revisited)

Moderator’s note: we have an updated and condensed version of the following here: https://audiokarma.org/forums/index.php?threads/tldr-deoxit-guide.850968/ I was asked to re-post this semi-ancient post that has been long buried in the archives and I was reluctant to re-post anything already in...
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Thank you both very much for chiming in! These are great resources for a newbie like myself. I took them into consideration and everything is sounding great tonight - party time!
 
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