Sansui TU9900 FM Tuner

[Rayradio7973]

Sansui TU9900 fm Tuner. No audio left channel (FM only). AM and 1000hz test signal audio both channels. Stereo light and meters work fine. Any clue?

 

[rayma]

Maybe the multiplex decoder.

 

[wiseoldtech]

Selector switch could be dirty/corrosion.

 

[RJM1]

Service Manual
https://www.google.com/url?sa=t&rct...0service.pdf&usg=AOvVaw38EsuNOZMGMc7SFVh3L3xz

 

[wiseoldtech]

Judging from that schematic, this is a highly sophisticated and complex tuner.
My earleir comment about checking the selector switch(s) and doing a cleaning of them still stands, as a first solution.
If that doesn't bring satisfaction, then a careful and intelligent amount of troubleshooting is then required.