On Aug 19, 12:41*pm, Puddin' Man wrote:
On Wed, 18 Aug 2010 22:21:21 -0700 (PDT), wrote:

*...

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.

This is consistent with my experience with them. I've been running
mine 15-16 hours/day for about the last 10 years.

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).

I am finding Q705, Q701 and 702 markings and the regulator transistors
etc on the main board/heatsink, no problem.

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.

If you could render just a rough break-down of what was involved
in resoldering the regulator transistors, it might well enable
me to repair this unit.

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.

I am:

a.) A relative bonehead re detailed electronic repairs.
b.) Willing to learn. Retired, with a house-full of electronic stuff.
* * Much of it can't be replaced, something breaks most every day.

I can post pics if it would be helpful.

* Thx,
* P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

A simple voltmeter can give a lot of information particularly while
it's in 'failed' mode. While power devices (transistors and the main
audio power IC) can go 'thermal, I haven't seen a thermally sensitive
transistor in many years. The most common way back when was the TO-220
case devices - just like Q 701,702 and 705 but I would put money on
bad solder joints.

G²