I replaced all the transistors and electrolytic capacitors in this amplifier including the Phono section/Equalizer F-2570 about 5 or 6 years ago. I have only just got my Onkyo CP5000a turntable working for about the last week and have only just noticed one speaker sounding weaker, I noticed it at first actually but it must have been intermittent? It was only now and then that I would think one channel was down compared to the other but then it would sound OK and I thought I was hearing things? Now I can tell one channel is down for sure! I checked with the CD player and that was good playing on both channels equally well So I tried the TT on another amp and it was OK! playing on both channels So what I need now is some advice on tracking down the problem on the F-2570 board because that's the only place I can think the problem would be?
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First thing I would do is to Deoxit and reseat all the connectors and clean the switches, (the switching is quite complex), test again, then check for any dry joints.
I assume you have the service manual :-
Sansui AU-11000 - Manual - Integrated Stereo Amplifier - HiFi Engine
Beyond that you really need some test gear, at least a DMM, ideally a 'scope, but the fact that you're asking this question probably means you don't have these.
As an alternative, and if you're up for it, with the volume turned well down, try probing each channel in turn at the same point, working from the volume control back toward the input sockets. The buzz level should be the same, but as you work toward the input you will come to a point where the difference occurs. Somewhere close there is your problem
Good Luck
I assume you have the service manual :-
Sansui AU-11000 - Manual - Integrated Stereo Amplifier - HiFi Engine
Beyond that you really need some test gear, at least a DMM, ideally a 'scope, but the fact that you're asking this question probably means you don't have these.
As an alternative, and if you're up for it, with the volume turned well down, try probing each channel in turn at the same point, working from the volume control back toward the input sockets. The buzz level should be the same, but as you work toward the input you will come to a point where the difference occurs. Somewhere close there is your problem
Good Luck
Fixed!!! I read the Trouble Shooting guide in the Service Manual that said to check the load switch and because I have some badly torn ligaments and muscles in my shoulder, I just switched it in and out about 50 times instead of spraying it with DeOxit first. I will do that later on when I'm capable of wrestling and lifting this beast again. I have a Fluke 87 V that seems to take care of things. The reason I asked for help was that I felt helpless I suppose with this shoulder playing up as it is and not being able to move the amp! Anyway, things worked out well so thanks for the input mate.
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