Great to hear you were able to sort out the problem with a home solution.
I've had my T775 for 6 years now, under warranty the audio drop out, Check DSP Board error (AM200) and noisy fans were repaired (no components were replaced, all repaired/FW updated). I then got a relatively smooth 3.5 years, were only start-up fan noise was a problem last winter.
In the last few weeks a zone 2 channel has gone and I get the Check DSP board error for ~3 minutes on cold mornings and then it is fine for the rest of the day.
Inspired by your success I took it apart, cleaned the MDC card contacts (the repair shop said that is all they did last time around) and re-soldiered what looked to be a dry joint on on the 1952 transistor on the AM200 card, but the unit is no better or worse after my tinkering.
The blown channel I didn't even attempt to fix, far more disassembly than I had time for.
As per your thoughts over the years I'm always vacillating between sending it out for professional repair or just calling it quits on NAD reliability and finding something else.
Last edited by nijimon; 05-25-2019 at 04:02 PM.