apsent posted:
My Collins 75A3 ceased playing. I measure -115 VDC on the grid of the
audio stages (6AQ5)and it is supposed to be -10 VDC. Plate and screen
grid voltages are fine. Would appreciate suggestions of what the most
likely problem might be.


I don't have a schematic for the receiver, but my initial thought is the grid
bias is created by a cathode resistor to chassis ground. Did you measure the
-115V from the 6AQ5 cathode to the Control Grid (G1)? If yes, the cathode
resistor is open, or has fried to a very high resistance value.

Don