on the back it has the bias adjustment and bias test jacks. i have read that the factory bias setting is -55v for these amps ('74 T). so, i place one of the probes inside the bias test jack and the other on the chassis and adjust the bias adjustment with a flathead screwdriver. i just need to know, which probe (pos. or neg.) goes on the chassis and which one in the bias test. thanks.
Normally probes are black and red colored. What makes them positive or negative depends on which meter port they are plugged into.
I plug the black lead into my ground (or common) port on the meter. I plug the red lead into the "other" meter port (this will vary by meter). I insert the black lead into the bias test jack on the amp, and connect the red lead to the chassis.
I use an analog meter. This allows me to read negative volts.
If you have a user guide for your meter, look up how to read volts - and with some digitals, the polarity of the voltage doesn't matter like it does with analog meters.
