Just as a point of interest, since Chony is going to have the 8000 professionally repaired -- the headphone circuit Gary posted shows use of only 5 of the 7 available jack connections. Three of them are for the headphones (left, right, common ground). Two more are likely used to mute the speakers (I assume the 3000 shuts them off when phones are plugged in, as is usual), but the jack apparently isn't doing the work directly (otherwise the unused two jack switch contacts would be connected). It appears therefore that any actual speaker switching is done elsewhere, perhaps by a relay or other device(s), and the jack just switches that circuit.

That's why, since I don't have a schematic, I asked for a picture of the 8000's actual headphone wiring. If the 8000's circuit is like the 3000's, the speaker problem may not at all be related to the headphone jack.
In fact, some keyboards have a separate amp to drive phones, and if that's the case the speaker amp could be out on one channel and the phones would still work on both.

Enough conjecture; Chony, when you get this fixed, would you let us know what the actual problem was? BTW, if you're in upstate NY (not NYC), I might be able to take a look, if you'd like.

--Barry

Just as a point of interest,my KN7000 lost the right main speaker. My earphones work in stereo. My repairman told me I could have inserted a wrong plug to mute the speakers,and shorted out one side of the amp. He is a factory authorized technician.
Bernie

Barry,

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" They don't use any relay. Also the Outputs (Fixed and Variable) have their own Op Amps.

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Have a nice day

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.

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

Hey Gar: You got E Mail......Pose

I checked trouble shootin in the shop manual on the psr9000, which may be about the same,as the 8k only thing I could find that's not been suggested is a plug left in the aux send (right)on the back, will block the sound on the right?? probably not it! But check out that jack (possible stereo phono plug could have damaged it or somehow so's its not grounding out.)

I'm not very knowledgeable on solid state
electronics, but years of trouble shooting on electrical and mechanical devices taught me to look first at what the history of the device is ie whats the last thing done to it, or what was going on at the time. Seems This board has been apart a couple of times recently if my memory is correct and if I've got the story straight. Seems like there was something unplugged or something, My thoughts are remove the back and take a good look at all the plugs, and move every wire to see if a ground or something may have been missed in reconnecting....Just a thought, usually something very minor. (that 8000 is built like a sherman tank) Hope you find it........Cheers....Pose

Thanks for checking; it would be nice if Chony's problem turned out to have that simple a cause. Unfortunately, according to the PSR-8000 Owner's Manual, a disconnect at the loop send jack would result in no output at headphones and aux-out, in addition to speakers. Since Chony said the phones and aux were working, I assume that can't be the problem.

--Barry