On Aug 18, 5:52*pm, "William R. Walsh"
m wrote:
Hi!

Receiver is in a cabinet with little ventilation. Obviously
likely to be a
heat related problem.

You should move it to a place where it can get better ventilation.
Some of
these run quite hot.

Is this receiver losing power totally, or do some functions (like
the
display and tuning buttons) continue to work? If it does, I'd bet
that it's
going into protection to save your speakers from a disaster. Most--
if not
all--of these units used Sanyo hybrid audio amplifier ICs (a large
many-legged black thing) and I think it's safe to say those were
the weakest
point of them. They don't like heat and it seems like Technics
skimped on
the heatsink in many of these units.

William

A properly operating SA-R210 idles at a very modest temperature.
Obviously it warms up if delivering serious power but by and large the
heat output is pretty modest - certainly not above average.

I just checked the service manual for the 210 and it does mount the
regulator transistors on the main heatsink flanking the main audio
power IC. Q705 reduces the -48 to -19.7. Q701 and 702 are in parallel
to drop the +48 to +15.6. Note that there are regulators following
these to achieve -13.9, +15.5 (capacitor multiplier) and +5.7 for the
microprocessor (using another diode to get to +5V).

On the similar SA-160 which has 2 regulator transistors on the main
heat sink, all 6 terminals were cracked loose. After re-soldering
those I unsoldered the main power IC and resoldered it too since it is
mounted the same way as the transistors. Surprisingly, none of the
foil pads were damaged.

On my R210 the solder connections under the volume raise / lower
buttons cracked making the buttons flaky. Re-soldering them left it
working perfectly again. No bad pads on this unit either.

G²