1569A Pot Adjustment

[bearwandaloid]

When adjusting the P2 pot for bias (37 volts), where do I place the DMM leads? They just arrived yesterday and I would love to get them up and running. Thanks for the help.

[jmarkwart]

bear,

Asking where to put the DMM leads implies you are not experienced measuring tube circuits. Be very careful! Tube amplifiers, like the 1569A, carry lethal voltage and current potentials when operating, and should only be serviced by electronic techs, or knowledgable and experienced amp builders.

Jeff

[Fitts]

I noted that you said looked at the schematic and saw the voltage setting to use of 37 volts. To get you started, I would recommend that you measure your grid voltage at the tube socket. Find the pins for the grid and cathode and attach your DMM there, negative to the grid and positive to the cathode. Since the cathodes are probably grounded directly to the chassis, you can probably just attach your positive lead to any convenient point on the chassis.

Be careful, you are working with voltages that can be dangerous and with circuts that have capacitors that hold charges long after the amp is shut off.

Regards,