Quote:
Originally posted by John_CA:
According to the schematics of the 3000, the headphone jack (which does have it's own Op Amp and Power Amp circuit - 0.65W 2ch) silences the speakers by triggering a Mute circuit. Each channel has a transistor switching, detected then by a "Decrease Voltage Detection Circuit"

Thanks for that information, John. It looks like my conjecture (based only on seeing the pc board layout Gary provided) was correct.
It was obvious that only one of the jack's switching contact sets was being used, and that to mute both channels additional circuitry would be needed.
Quote:
They don't use any relay. Also the Outputs (Fixed and Variable) have their own Op Amps.

Not having the schematic, that's why I said "relay or other device(s)"; FETs are often used in this application (due to their low "on" resistance), although bipolar transistors can do the trick as well. If the PSR-8000 has a similar arrangement, a failure of a transistor in the mute circuit is another possible cause of the loss of output to one channel's speakers in Chony's unit.

So, does anyone have similar info about the PSR-8000?

--Barry
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Yamaha: Motif XF6 and XS6, A3000V2, A4000, YS200 | Korg: T3EX, 05R/W | Fender Chroma Polaris | Roland U-220 | Etc.