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Panasonic SA-HE200 receiver/amp -- overload

This Panasonic SA-HE200 Receiver/Stereo/Amp came in with the display indicating "overload" and "turn power off" a few seconds after the power is turned on.

Has anyone had experience with this symptom or do you have a service manual/schematic?

Some background:

According to the owner's manual, the panel indication suggests a shorted speaker terminal, too low impedance speakers, overdriving, or high heat conditions, all problems at or after the final amps. However, the symptom appears on a cold start up without any external connections. I've ensured there are no stray bits of speaker wire shorting the terminals and checked back to the main pcb for shorts.

The intregrated outputs (IC 601 and 602) are 24 pin RSN310R37 multi-channel mosfets. I did a left-right channel terminal-by-terminal check of resistance and voltage and they are the same (of course, it could be a problem common to both). Main power to the amps is plus and minus 56V, consistent with the 63V filter caps. I have not been able to find any data on the mosfet IC.

Michael (C.E.T.)

please post reply, thanks

Reply to
Michael
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I'm still thinking it's an output IC, in spite of your voltage readings, but some of these Panasonic units also used an STK voltage regulator - seen some problems with those....

Panasonic service manuals typically aren't too expensive - their US phone number is 800-833-9626.

Mark Z.

Reply to
Mark D. Zacharias

Mark Z:

It could indeed be a defective 3-channel output IC (there's two of them). But at over $US75 each, it'll be worth the effort get the diagnosis right the first time :-)

Probably best to figure out what the self-test system looks at that would give an "overload" display (and, incidentally, turn the cooling fan on). I'm working on that, but in the meantime, the service manual has been ordered. Tnx.

but

some

Reply to
Michael

With the schematic in hand the problem was positively traced to a defective overload/overheat circuit within one of the two three-channel IC's.

Mark Z, you were correct, and yes, the manuals are very reasonably priced. Thanks.

Michael

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multi-channel

data

Reply to
Michael

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