DUMKOPF !
 

So I am working on this Sansui AU9500 with a channel out. It had TWO problems, one was the input coupling cap on the main amp, and there was also a bad cap on the preamp board with one leg eaten off.

So I fix all this **** and I still got one channel out. I am sitting ther like WHAT THE **** !

Then I dcide to test oput the switching ****, maybe the problem is there, and I DO get output on both channels whne plugged into tape monitor. More WTF ! what is different, does this thing have some kind of - WHAT ??

Well, the thing is almost all heavily anodized aluminum and the best ground I could fing for the scope was at one of the RCA jacks on the back. the one I chose was "TAPE OUT". Sumbitch, what happned was I hit the dubbing switch and when turned to either dub from tape one or two I got both channels. When on source I got both channels.

The reason was that the ground clip lead on that output was shorting the signal ! Now mind you I am 100% sure about these caps. One reads infinity ESR, and the other even higher, I mean with the lead missing and all. I am sitting there, like, WTF, this thing has THREE problems ?

Of course that does prove a mistake by the engineers. A tape output like that should be isolated by at least a 1K resistor or something, or whatever will allow it to not affect the signal. this reminds me of a long time ago whenI used a Sanyo Beta HIFI VCR for audio. When the VCR was shut off it caused distortion in the audio because it was directly feeding a transistor with the power removed.

Another thing is if you wanted to use another integrated amp, let's say off the pre-out. Some oldr ampos actually short out the inputs they are not switched to at the time.

Of course this could not happen with this unit I think because it switches out the pre out when you set the switch to couple rather than separate. Now what if I wanted to bi-amp ?

Think of all the things they didn't think of sometimes.

Whatever.