07-17-2017, 05:20 PM
Here is the schematic for the R-12-R-T, which is the closest I can find to my R-12-R-M, converted to jpeg for easy viewing:
Note this shows 7 tubes??? What gives here?
Starting at the power tubes, and referencing voltages from an RCA tube manual, I'm finding the following plate voltage:
Pin 4 - 378 VDC
Pin 3 - 375 VDC
This is the same for both power tubes.
Moving to phase inverter (12AX7), with amp idling (no input signal), I'm only reading .3 VDC at pin 1, either with tube plugged in or removed. According to manual, this should be several hundred volts. Does this sound normal? Comments please?
Note this shows 7 tubes??? What gives here?
Starting at the power tubes, and referencing voltages from an RCA tube manual, I'm finding the following plate voltage:
Pin 4 - 378 VDC
Pin 3 - 375 VDC
This is the same for both power tubes.
Moving to phase inverter (12AX7), with amp idling (no input signal), I'm only reading .3 VDC at pin 1, either with tube plugged in or removed. According to manual, this should be several hundred volts. Does this sound normal? Comments please?