3rd Power Kitchen Sink 6VEL User Manual page 15

Back Panel: Power Tube Biasing
35 34 33 32
CAUTION:
NEVER touch hot tubes!!! Temperatures can exceed 500˚F and cause severe burns!
CAUTION:
Read all of the information and procedures in this section before attempting to modify the factory
bias settings of your amplifier.
Power Tube Bias Adjustment Control (32)
Controls the amount of negative DC bias voltage being fed into both output tube input grids. Insert
a mini flathead screw driver into control port and rotate counter-clockwise to lower the idle current
setting (operate cooler). Rotate clockwise to increase the idle current setting (operate hotter).
V9+ Voltage Reading Terminal (33)
This terminal is internally connected to a one-ohm resistor on the output tube cathode of V9 (the
power tube on the right). When monitoring the current here, you will be reading millivolts on your
portable multimeter. You will need to connect your positive (+) test lead (typically red) to this
terminal.
GND- Terminal (34)
This terminal is internally connected to chassis ground. When monitoring the current of either
output tube, you will need to connect the negative (typically black) test lead here.
V8+ Voltage Reading Terminal (35)
This terminal is internally connected to a one-ohm resistor on the output tube cathode of V9 (the
power tube on the right). When monitoring the current here, you will be reading millivolts on your
portable multimeter. You will need to connect your positive (+) test lead (typically red) to this
terminal.
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