First startup ... Pls Help!

[mlineHK]

hi Paul,

these r the results after re-solder every contact on all 3 boards.


IA A and B 274v
6.3 57v
-6.3 52v
275 275v
Biasing 1.45v


Breg A 273v
Breg B 216v
Kreg A 1.18v
Kreg B 10.66v
OA 1.76v
OB 2.02v

[Paul Birkeland]

Resoldering your connections brought one side into proper operation.  I would suggest that you also resolder the center PC board and perhaps that will fix the other side.

[mlineHK]

That's what I thot and I have done re soldering the middle board as well. I will redo again and see. 

[Paul Birkeland]

You could also replace the 431 regulator on the side with the very low Kreg voltage.

[mlineHK]

Thank you Paul will try to replace them.

[Paul Birkeland]

Thank you Paul will try to replace them.

It, you definitely don't want/need to replace the working one.

[mlineHK]

Yes will replace the a side one.

[mlineHK]

hi Paul,

after replacing the A side LM431ACZ ,  the results remain unchanged.  what do u suggest I shall do next?

[Paul Birkeland]

Have you reflowed all of the solder joints in the amp?

[mlineHK]

All joints on 3 boards only.

[Paul Birkeland]

I would go over the 12AU7 socket and associated terminal strips as well.

[mlineHK]

ok will do thanks.