Asimov:
Only very, very, very, very few amplifier designs can play into a
short-circuit without damage. Even expensive and well designed power amps
can have catastrophic failures when loaded into a short-circuit.
As you know, fusing the speaker outputs will help protect the speakers from
the dc rails if the output stages short out, but the amp will be already
fried.
It is my frequent observation that the Pioneer design that we are discussing
is not tolerant of much at all and is prone to failure when other amps keep
on working. It is my opinion that putting expensive repair money into a
flawed design is a waste and would be better put to use in purchasing a
decent Yamaha or similar receiver.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
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"Asimov" wrote in message
...
"sofie" bravely wrote to "All" (31 May 04 19:41:45)
--- on the heady topic of " Pioneer M-790 amp adjustment"

Power amps often require a lot of patience in testing and therefor
take "a lot of time" to do right. Otherwise one ends up with a pile of
expensive burnt replacements and have to start all over again. As far
as I'm concerned if a consumer amp can't play into any kind of load,
including a short circuit, without damage then its design is flawed.
Modules are very bad for this. Fusing their output might help.

so From: "sofie"

so Mark, James, & Asimov:
so Quite frankly when I get these models in my shop with blown outputs I
so usually recommend that the unit is not economically repairable.
so Proper component level repairs are not only very time consuming and
so are prone to "blowing" again for a variety of malfunctions .... also
so replacement power output modules are becoming quite scarce and again
so can be prone to blowing because of the very poor design..
so In my opinion this is obviously not a shining example of Pioneer's
so engineering and manufacturing prowess...... gone are the days of the
so very well designed grand Pioneer "super" receivers of the 70's and
80's
so like the SX 1250 and other fine pieces.

... A fail-safe circuit will destroy others.