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48-200 code121 Filament Wiring incorrect
#14

Hi Rich,
I noticed that no one posted the service info to your set  [Image: http://philcoradio.com/phorum/images/smi...lleyes.gif] so here it is:  http://www.nostalgiaair.org/pagesbymodel...013627.pdf  For a lot of us old timers we sort of have these circuits memorized so we don't refer to them often.  It was a fairly common practice for manufacturers after the war as parts were difficult to source to interchange electrically equivalent tubes w/different sockets. The 35Y4, 35Z5, and 35W4 or the 50A5, 50B5, 50C5, and 50L6 are two of the common sets of tubes (rectifier and audio output) that can be used. Sometimes the schematic will display the one you have in your set. On Philco sets a code # like 121 or 122 along w/the model. The code may indicate a slight difference from the same model.

So here's a plan. Double check your ac and heater wiring for correctness with special care around pin 4 of the 35Y4 . Use your ohm meter to check the heater in the 35Y4 by seeing that pins 1,8,and 4 have a low resistance against each other. The capacitance value of the filters isn't very critical 33ufd is fine.

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


Messages In This Thread
RE: 48-200 code121 Filament Wiring incorrect - by Radioroslyn - 11-21-2017, 10:48 AM



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