No hum on pin 3 of 47.
I think the power transformer is bad. Can't get a steady reading on any of it and I don't get any readings on the other tubes.
Ok remove the 80 tube. Set meter to >500ac. Measure voltage from the ungrounded side of R-12 (should be a big resistor, wire comes from the power transformer) to pin 2 of the 80 socket and then pin 3 of the 80 socket. Should see about 300-350vac on pin 2 and then pin 3 should be the same. If that is OK check R-12 it may be open.
Terry
I don't get any voltage readings on pin 2 or 3. Actually, one one of the pins (not sure if it's pin 2 or 3) the meter starts at over 1000v and drops to 0v. The other starts at about 20v and drops to 0v. R12 checks good. It's a 400ohm 5w resistor and it checks at 408ohms. With the set turned off, pins 2 and 3 show 358ohms and 386ohms. Not sure that matters, though.
Try measuring the AC voltage across pins 2 and 3 of the 80 socket with the power on. Should see about 600vac. Be careful. Hope the transformer is good cause the replacement is going to be hard to find.
Terry
Hope springs eternal but this time the fates got to it. Measuring between pins 2 and 3 with the power on shows infinity.
(07-05-2015, 10:07 PM)dseverson Wrote: [ -> ]Hope springs eternal but this time the fates got to it. Measuring between pins 2 and 3 with the power on shows infinity.
Autorangning meter? Can it read 600 or 700vac? Some digital meter won't read that high of an AC voltage.
Terry
No, it's not autoranging. I set it to read from 500v to 2000ma.
dseverson, your post on meter reading setting does not make a lot of sense to me. Is it set to max A/C reading and if so is that 500V A/C? The statement of 2000ma is confusing unless your measuring current. If you are at 500V A/C it is understandable as Terry indicated that your meter will not read the voltage present as it is too high.
Go back to Terry's post #17 so you can measure each leg (plate) to the chassis. It should cut the voltage in half and be within the range of your meter.
Best, Jerry
Finally got back to working on this radio. I went back and removed the 80 tube and took voltage readings on pins 2 and 3 fromthe ungrounded side of R12. I get about 380 volts on both. Also checked R12, a 400 ohm power resistor - not sure of the watts. It measures 408 ohms.
OK so plug in the 80 tube and with the set on measure the DC +voltage from pin 1 or 4 to the chassis. Should see a couple of hundred volts. Next measure the DC voltage on pins 2 and 4 of the 47 tube separately to the chassis. Again should see a few hundred volts at both.
If you like I can send you a pm with my fone# Might be easier and quicker that all this typing!
Terry