I have a Phase Linear 400 Series II on my bench that has two LED's lit up on the right end of the meter when (and where) they shouldn't be. This is as soon as I power on the amp, no signal.
What I've done so far:
Apologies for the resolution of the schematic.
What I've done so far:
- Checked all electrolytics. One was open (C304).
- Checked all resistors and diodes.
- Exercised the trimmer, R306, applied a few drops of Faderlube, and reset it to match the other board.
- Checked all transistors in circuit, comparing boards.
- Checked everything, including the two UAA170's, with my curve tracer/octopus tester. No evidence of leakage, though the test voltage is lower than what would be seen when the amp is on.
- Replaced the RC4558 (Z301).
- Checked for cracked/cold solder joints.
Apologies for the resolution of the schematic.