01-26-2022, 11:51 AM
Seems like the 42 output tube is not conducting current which is why your power supply and plate voltages are high and the voltage across resistor #47 is low. You tried another 42 tube so its not the problem.
Check and see if the cathode pin of the 42 is actually grounded to chassis. As terry mentioned, sometimes the ground connection is made through a tube socket rivet. If the rivet is loose or corroded you may lose the ground connection and the cathode will be left floating and unconnected. If that's the problem, solder a short wire from the cathode terminal to the nearest good ground terminal.
Check and see if the cathode pin of the 42 is actually grounded to chassis. As terry mentioned, sometimes the ground connection is made through a tube socket rivet. If the rivet is loose or corroded you may lose the ground connection and the cathode will be left floating and unconnected. If that's the problem, solder a short wire from the cathode terminal to the nearest good ground terminal.
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