Zero OA Voltage D side [resolved]

[BenjaminSmith]

Issue:  0.0 OA voltage, D side. 530V on IA. No B side LEDs lit.  Zero voltage on 46U. Kreg 0.08V A side, 0.9V B side. Amp has passed all previous tests.  Help, please!

[Paul Birkeland]

I would reflow all the joints on that PC board other than the ones where LEDs attach.

[BenjaminSmith]

Paul,

All joints checked and reflowed.  Still dead.  I neglected to mention that I had initially connected the 26U black wire to +reg instead of -reg (now corrected), possibly leading to the vaporized LEDS.

[Paul Birkeland]

I did not notice the vaporized LEDs.  You'll want to replace that entire C4S board with a fresh one.

[BenjaminSmith]

Probably because I neglected to post this pic 

[BenjaminSmith]

The new board arrived, went together and was installed.  It works perfectly.  Now the issue is with the A side board which was just fine previously. IA measures 530V per manual. OA also reads 530V, not 300V. Terminal 32U was measured as it did before the D side board went in, adjusted and stable at 175V. The LEDS on A side of A socket board do not light (the B side light as they should) whereas on the opposite D side all four light appropriately.

[Paul Birkeland]

A board that works and suddenly doesn't work will generally do so from flaky solder joints.

[BenjaminSmith]

Issue resolved.  Red wire from D4 to OA was busted directly underneath board. I've had trouble with solid core wires breaking after repeated movement - I may be scoring the wire as I strip the insulation.

Anyways, thank you Paul. I should be listening to sweet music in an hour or so!