FPALB
Well-known member
I have this 480A that just came in that the owner says is red plating after playing for a half hour or so.
I put in some 1ohm resistors to check the cathode currents and put in a bias pot replacing the 47K resistor in the bias circuit.
The funny thing im seeing is that the plate voltage is changing when I adjust the bias - haven't seen this before.
Any ideas here?
100k grid to bias resistors are spot on
Changed the coupling caps
I put in some 1ohm resistors to check the cathode currents and put in a bias pot replacing the 47K resistor in the bias circuit.
The funny thing im seeing is that the plate voltage is changing when I adjust the bias - haven't seen this before.
Any ideas here?
100k grid to bias resistors are spot on
Changed the coupling caps
