Setting Initial Negative Bias Voltage

The Amp should be completely assembled at this point.
This will be the second power up of the amplifier. And must be done before proceeding. (Link here to 1st Test)

Rules:
Fuses IN
No Tubes
Use On Switch Only
Keep in Standby
No Need for Speaker or Load attachment but it never hurts to be safe.

Turn the bias pot all the way to either the left or right stop. Plug the black ground lead of the Multimeter into the center black test jack at the rear of the chassis (ground).
Set Multimeter to DC Voltage. Locate Pin(s) 5 with Grid resistors on them.
Power on the amp and the multimeter. Make sure nothing is smoking before moving forward.
Touch the Red lead to the top of the resistors on Pin 5. It should be either -40 or -70 VDC and all should be the same.

Turn the bias pot and watch the voltage. It should be responsive.
Turn the bias so that it is at its most negative value (-69.2VDC)

Shut off the Amp. Unplug it. Drain all capacitors.

SLO
<< Previous - Next >>

-Return to Gallery-

-C3 Amps Home-