William R. Walsh m wrote
in message ...
Hello all...

Just thought I'd drop in and provide a quick status update. I learned a
few
things along the way:

1. STK-2038 and 2038 II modules are not at all the same. Someone (not
here)
told me they were electrically compatible with each other, and this is not
so. The STK-2038II has more pins and seems to be less commonly available.

A few people pointed me in various directions, and one pointed me to a new
old stock STK-2048 II module, still sealed in the factory wrapping. I
opted
for that one; it's used in the next model up (the SA-410).

2. Nothing more than installing the new module was required. Everything is
playing great now.

3. I'll never push the unit *that* hard again (turned it up about halfway
and that was when it started to fold).

4. The internal protection circuit absolutely will NOT save your speakers
if
anything goes wrong with the power amplifier. I was using an outboard
speaker protection device and it did the job when the hybrid module went
the
rest of the way.

5. Computer Drive and its method of forcing the transistors in the hybrid
to
remain turned on to some degree at all times seems to make them run really
HOT. Every SA-310 and 410 I've ever seen gets very hot, especially when
idling. I'm going to install a fan. The heatsink becomes ridiculously hot
within ten minutes of operation, so hot that it can't be touched. I don't
think this can be good for the hybrid.

I learned a lot and I appreciate everyone's help and commentary from this
group. I have no intention of finding out, but I do wonder what Computer
Drive actually *does* when the 60C temperature sensor attached to it
trips...? Honestly I'm surprised it hasn't--a 50C device is at least
touchable. This really isn't. And all the service manual says is that the
"Thermal" LED on the Computer Drive Monitor goes out when this happens.

William




If the "outboard speaker protection device " is a "crowbar" how do you know
it was not a failure in that which knocked out the amp ?