Posts: 7,323
Threads: 270
Joined: Dec 2009
City: Roslyn Pa
After working on a bunch of other stuff the 21 is back on the bench. Last I checked it had an open primary on the audio driver transformer and two of the rf coils had open primaries. Tnx to a few here and elsewhere I was able to get enough spares to get it back together. Started by checking the audio transformer and it was bad and I replaced it. Then rechecked the rf coils and they checked out OK. Rebuild the speaker a few weeks ago so I was going to put power to it and see what happens but I'm out of line cord.
Mohawk school is next week so I'm going to try to get it working before then. Have a customer job to get done too a RCA Orthophonic AM/FM job from 1958. It's one BA set! It's kinda strange working on a model T and new Crown Vic. Both are fun!
Terry
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 it!
Terry
Posts: 7,323
Threads: 270
Joined: Dec 2009
City: Roslyn Pa
Picked up some cord and fitted it to the plug and the set. Fired in up with no tubes and the dial lite didn't lite. Quick check and found the bulb was bad. Replaced and it lights just dandy. The BC resistor looks to be burned up as it as loose turns on it. Checked it and the resistance is good. Filter has been replaced look ago. Suspect that a leaky cap over heated the BC resistor. Now it has insulation wound over it. Looks to be something a heavy gauge thread? That's what was loose and unwinding on the BC resistor. Put in two new filters in the p/s but have to run to pickup my daughter. So far the dial light works swell!
Terry
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 it!
Terry
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Keep up the good work!
Yes, the old "B-C" resistors are covered with what looks like heavy thread; this covers up the resistance wire underneath.
--
Ron Ramirez
Ferdinand IN
Posts: 7,323
Threads: 270
Joined: Dec 2009
City: Roslyn Pa
Was able to spend a little more time on it and check over a couple more things. Dropped in the tubes and hung a volt meter across the HV line. Plugged it and gave the off/on switch a twist. Was measuring the HV at the high end of the BC resistor. Seems like the p/s was only making about 150v. Was thinking it must have some leaky bypass caps that are loading the HV line down till I measured the HV at the plate of the output tube (45). I had about 275v there. It seem that the field coil is of sufficient resistance with the load of all the other tube and bad caps that there is 120v drop across it.
Anyway the set is working but need to replace the paper caps and check the resistors so I can get it's maximum performance.
Back to the bench
and to the Orphononic RCA
Terry
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 it!
Terry
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