Ceriatone Overtone Special User Manual page 11

In these pictures, we have color coded the important features for simplicity
1) Blue arrow = bias adjustment potentiometer shaft
2) Yellow arrow = power tube pin connected to 1 Ohm bias measurement resistor
3) Red arrow = ground pin connected to 1 Ohm bias measurement resistor
NOTE – each power tube socket has a 1 Ohm bias measurement resistor connected to a ground pin near the rear of the
chassis.
To measure your power tube bias, carefully follow these steps with the amplifier in OPERATE, MASTER at minimum, and
connected to a speaker load (not doing so may damage your amplifier!):
1) Turn on a digital multimeter (DMM), and set it to read millivolts (mV) in the 100mV range (this will vary from DMM to
DMM)
2) Plug a black probe into the color-coded jack on your DMM, and do the same for a red probe
3) Touch the black probe tip to the ground pin connected to the 1 Ohm bias measurement resistor (red arrow). This is
GROUND in the OTS amplifier.
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