CRACK OTL - Issues After First POWER ON [resolved]

[Paul Birkeland]

Based on your voltages, at least half of the 12AU7 is glowing.  It can't be that both halves don't glow.  Please recheck with the light off in the room.

Also, can you measure (carefully) the DC voltage at A7?

[mipheres]

Hi,

DC Voltage on A7 is 0 - zero.

[Paul Birkeland]

Based on your voltages, at least half of the 12AU7 is glowing.  It can't be that both halves don't glow.  Please recheck with the lights off in the room.

[mipheres]

yes, looks like both halves glow.
see attached

[Paul Birkeland]

Carefully check the voltage at A8.

[mipheres]

A8 measures 11.3V

[mipheres]

Bump

[Paul Birkeland]

You can replace the LED or wire in a jumper from A3 to A8.  (The LED has likely taken too much heat and has fractured)

[mipheres]

sorry I dont know what to do exactly. can you write a more detailed explanation?
Thanks

[Paul Birkeland]

sorry I dont know what to do exactly. can you write a more detailed explanation?
Thanks

Connect A3 and A8 with a piece of wire.

[mipheres]

Hi,

Looks much better now.
all measurements are around the documentation values:
where it says 90V in the document I measured 82V
where it says 170V in the document I measured 162V

Also at the TRS Peak test, I measured 10V and the decline was to 0V.

Do you think I can connect the HD650?

Best regards,
YM

[Paul Birkeland]

Yes, I think you're ready to go.

-PB