Responding to this thread because the OP had Audio Research quote him $2,000 for repairs.
The issue is ARC no longer services this unit and "doesn’t" have replacement caps for the Philips units in the amp that tend to go bad. Last time I talked to ARC they said the D400 mkii was "unserviceable." Not sure if anything has changed with new ownership.
The issue is the caps are direct-soldered to the boards, which makes the amp a PITA to work on. The tech at Pyramid Audio did me a solid by feeling sorry for me because the amp I bought on Ebay (with leaking caps) wasn't working, and he didn’t want me to be left with a very expensive paperweight.
Without the receipt I think it cost me $650 or so for the repair. So, Pyramid Audio is a place that can possibly help, but he wasn’t exactly excited about working on one again lol
Audio Research D400 mk2
Recently when powering up/down one of the 4 big caps under that big board arcs ( light blue)for a few seconds. The amp will power up ok and it stays on and sound great. If I just touch that area I hear a spark. I pull plug to power in/out as the switch seems to make it sound louder. Audio Research does not have caps anymore and say they will need to retrofit and replace that main board to connect to all wires , etc. under it. They say not o use it even though it powers up as normal ( less the spark, arc) for a few seconds or so.
Any thoughts as they say about 2 Grand to replace all for caps and rewire with a different board . Not including shipping.
Where's Leonard these days as he'd have a FIT.
Thanks George ( It Still sounds Good)