If someone is familiar with a US supplier for these, I would greatly
appreciate hearing from you. I'll check back here periodically. Thanks.

Check QSC's website www.qscaudio.com IIRC. The chermatics are there.

The IXYS devices are probably not the ones originally specified and
they're
just 'commondity' N-ch mosfet or IGBTs most likely.

Graham


Already downloaded it before I bought the amps (to study the circuit
topology) so I could research the build quality of the design.
These amplifiers have an outstanding reliability track record, based on the
many sound touring company owners I've spoken with last year, when I was
deciding which amps to purchase. However, this one failed while turned on,
but idling. QSC tests their amps by shorting the outputs, driving it to
clipping, and blocking the air intakes and then retesting them to see if
they meet spec, according to their marketing materials. So I'm hoping that
this was a bad run of MOSFETs. I still often wonder why these fail when not
under stressful operating conditions. Impurity in the die at manufacture
(unclean cleanroom?) bad seal on the plastic case? Dendrites growing across
the p-n junction over time?
Another thing I noticed was the use of copper 'ribbon wire'--flat copper
strapping for the hf power supply wiring to and from the main switching
transformers--which was insulated with thin Kapton or similar tape. There
was a section on the bottom that looked like the Kapton insulation had
burned through, causing me to wonder if there was an arc between two
adjacent (but touching) conductors, due to the way it was manufactured.
The schematic actually calls for the IXYS devices by part number--that's
where I got the p/n from.
Fortunately, I killed the power before significant damage occured. Some
smoke and soot around the viscinity. I washed the board as best as possible.