07-01-2020, 07:32 AM
Have you tried changing the 50A5? It is possible it is dragging everything down or has an internal short once warmed up. Also, did you measure the resistance of the Primary side of the Audio Output transformer?
Some designs include a shunt resister across the bulb for situations where the radio is drawing more than 60ma through the 35Z5. You may want to do this, at least temporarily, until you figure out the real cause. See tube spec sheet for details.
To figure out which tube is pulling the voltage down, you may have to insert a meter and measure the current through each tube. Once you figure out the tube, focus on the voltages on the various grids.
Some designs include a shunt resister across the bulb for situations where the radio is drawing more than 60ma through the 35Z5. You may want to do this, at least temporarily, until you figure out the real cause. See tube spec sheet for details.
To figure out which tube is pulling the voltage down, you may have to insert a meter and measure the current through each tube. Once you figure out the tube, focus on the voltages on the various grids.
