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David Farber

wrote:
I hope you mean a QRX, not QRS. They got it at hifiengine, it shows a
fuse for the dial lamps, F 01, 5 amps. It also feeds a rectifier for
about an 8 volt source that feeds the stereo light, also off the
fuse. While at this age those lamps may have blown one at a time by
now, you would have noticed it.

the cap in the protection, the failure mode is weird. They are
usually 10 volts and sometimes go right across B to E of a transistor
so they never charge more than like a half a volt. they get leakier
and leakier over time. They are usually fed by a high value resistor,
like 100K or more. I didn't look at that part of the circuit but
since it is fine, fukit.

Not a badly designed piece. Full comp outputs, current source instead
of a bootstrap, DC coupled. Theoretical peak RMS short tem power is
76.5 WPC. The rating is 30, so splitting the difference I would say
you got about 1.5 dB or so dynamic headroom. It is probably over 3 dB
for a couple milliseconds, but in real life not so much.

Tuner is pretty conventional, uses ceramic filters but still a
standard ratio detector. No pilot cancel, but all that doesn't mean
it doesn't sound good.

Tone controls OK, filters only 6 dB, don't use the filters. he
variomatrix looks like a good thing, like Marantz varimatrix I would
guess. You have control over the L+R attenuatoin in the rear.

I don't see amp strapping in it though, or pre out/main in.

Enough commentary, if it is QRX the manual is at hifiengine.com. It
is probably ready for the FM to be tweaked, but it might not be so
bad. Other than fixing the lights, if all the channels sound good I
don't recommend anything. You could go in with an ESR meter and
replace caps if you feel like it. Just never short the speaker wires
because it has no current limiting at all.

Just a hunch here but I remember there were many Sansui models manufactured
in that era that had faulty rotary function selector switches. The result
was that the panel lights would flicker or go out completely. No amount of
switch cleaning would restore them to good health. If you wiggle the
function selector switch, do the lights flicker or does the meter function
momentarily?

--
David Farber
Los Osos, CA