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11-25-2016, 11:33 AM
If the local oscillator isn't working, the next thing to do is take voltage measurements on all the pins of the XXL tube and compare them to the service information. Another thing to do is, clean the tube pins and the tube sockets.
Steve M R Radios C M Tubes 
12-01-2016, 09:09 PM
I have all new tubes and still nothing. all voltages for the XXL tubes are nowhere near what the spec says. The plate voltage is 1.5V, whereas it should be 150V. In fact the only voltage that is high in the whole radio as far as I can tell is at the 84 tube and the voltage there is 480V. Way too high. Maybe there is a problem with the transformer.
12-02-2016, 01:28 AM
So what do you got on pin 3 of the 41 to the chassis (dcvolts). If you are not finding much there bet your field coil is open.
When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
12-02-2016, 07:26 AM
I get 1.7V from pin 3 of the 41 to the chassis. Yeah I thought abut the field coil. I couldn't really accurately measure across the field coil, The input wire is well coated right up to where it goes in. I didn't want to remove it. I tried to put a 1700 Ohm resistor across it last night from pin 2 on the 41 across it, but that didn't seem to help.
12-02-2016, 08:11 AM
(12-02-2016, 07:26 AM)ccbaker13 Wrote: I get 1.7V from pin 3 of the 41 to the chassis. Yeah I thought abut the field coil. I couldn't really accurately measure across the field coil, The input wire is well coated right up to where it goes in. I didn't want to remove it. I tried to put a 1700 Ohm resistor across it last night from pin 2 on the 41 across it, but that didn't seem to help. Measure the resistance from the cathode of the 84 tube to pin 3 of the 41. By connecting a resistor from pin 2 to 3 on the 41 won't tell us what we need to know. When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
12-02-2016, 08:43 AM
I'm getting a varying resistance in the several megohm range from pin 4 (cathode I hope) of tube 84 to pin 3 of tube 41.
12-02-2016, 09:21 AM
(12-02-2016, 08:43 AM)ccbaker13 Wrote: I'm getting a varying resistance in the several megohm range from pin 4 (cathode I hope) of tube 84 to pin 3 of tube 41. FC is toast. So do you have any tube type transformers laying around? Power, output, or a choke. When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
12-02-2016, 09:33 AM
Yes I have a couple of chassis's with at least speaker's that I won't use. Can I use something from that? I'll check again to see if these radios have a separate choke this evening when I get home from work.
12-02-2016, 03:33 PM
Here the deal old spkr is junk unless you can rewind the fc. Fortunately the fc is in the positive leg of the p/s so the resistance isn't super critical. Generally speaking the low the resistance the less inductance more hum. If you have a suitable eletrodynamic spkr then by all means drop it in. Since your set is a console the larger spkr a replacement pm spkr would have some room to mount a choke to replace the fc. For testing purposes a p/p audio output transformer's primary or the HV secondary of a power transformer or choke where just looking for some inductance.
You can replace it with a resistor but it's pretty inefficient as a filter inductance is much better. When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
12-02-2016, 08:52 PM
Well I'm very embarrassed but I have to confess that my measurements this morning were done without the speaker being plugged back in (this is my first floor model). I forgot to plug it in. With the speaker plugged in the resistance across the feld coil is exactly 1700 ohms (pin 4 of tube 84 to pin 3 of tube 41). The field coil is good. The voltages on the XXL are low as I said earlier, but about 50V instead of 150V, and not the millivolt range. So I guess I'm back to the problem being in the XXL.
12-02-2016, 09:28 PM
Ok . Check #38, 25, (resistance too high) 37(installed backwards needs to be w/ -toward the chassis) and disconnect one end of 17 and see if voltage increases at the XXL tube.
OBTW I do dumb all the time!!!!! When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
12-03-2016, 06:39 PM
I have now replaced every resistor in the radio. So #38, 25, 37 is correct, and I disconnected one end of 17. The voltage from the plate of the XXL tube is 44 Volts when measured to the chassis, and 64 V when measured to the negative end of #60. The voltage did not increase when I disconnected one end of #17. Still only static for this radio.
12-03-2016, 07:08 PM
I think at this point you'll need to dig up a signal generator so we can troubleshoot further. We don't really know it the IF stage is working and you'll need it for the alignment.
When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
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