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Philco 42-350 Transformer
5/16/2012 9:27:44 AMDave F
I just recapped the electrolytics, and tested all the tubes on this radio, however, there is a short as the transformer heats up and I get no sound. Is it possible that that block condensor near the transformer could be shorted? Any suggestions are appreciated.
5/16/2012 9:47:44 AMNorm Leal
Dave

Pull 7Y4 tube and see if the transformer still heats. If not transformer is good. Pulling 7Y4 takes the load off high voltage windings.

With the tube removed you could also verify voltage on each plate of the 7Y4. Both plates must have the same voltage for a transformer to be good.

http://www.nostalgiaair.org/PagesByModel/523/M0013523.pdf

If your transformer is bad should be able to find a replacement here:

http://www.oldradioparts.com/2a23efl.txt

Norm

:I just recapped the electrolytics, and tested all the tubes on this radio, however, there is a short as the transformer heats up and I get no sound. Is it possible that that block condensor near the transformer could be shorted? Any suggestions are appreciated.
:

5/16/2012 9:50:15 AMWarren
The block capacitor is across the primary of the transformer. This would not cause the transformer to overheat. Pull the rectifier tube out then power up the set. If the transformer still gets hot it probably has shorted turns. If it stays cool then there is a short in the B+ line. Make sure the filter capacitors polarity is correct. Positive ends on each side of the field coil.
5/16/2012 10:34:57 AMLewis L.
:The block capacitor is across the primary of the transformer. This would not cause the transformer to overheat. Pull the rectifier tube out then power up the set. If the transformer still gets hot it probably has shorted turns. If it stays cool then there is a short in the B+ line. Make sure the filter capacitors polarity is correct. Positive ends on each side of the field coil.


Unlikely, but there could be a short in the filament string to chassis ground.
Lewis
:

5/16/2012 11:05:48 AMClifton
And I believe the capacitor off the cathode of the rectifier goes to the centertap and not to chassis/ground.

Clifton


::The block capacitor is across the primary of the transformer. This would not cause the transformer to overheat. Pull the rectifier tube out then power up the set. If the transformer still gets hot it probably has shorted turns. If it stays cool then there is a short in the B+ line. Make sure the filter capacitors polarity is correct. Positive ends on each side of the field coil.
:
:
:Unlikely, but there could be a short in the filament string to chassis ground.
:Lewis
::
:
:

5/17/2012 8:13:12 AMDave F
:And I believe the capacitor off the cathode of the rectifier goes to the centertap and not to chassis/ground.
:
:Clifton
:
:
:::The block capacitor is across the primary of the transformer. This would not cause the transformer to overheat. Pull the rectifier tube out then power up the set. If the transformer still gets hot it probably has shorted turns. If it stays cool then there is a short in the B+ line. Make sure the filter capacitors polarity is correct. Positive ends on each side of the field coil.
::
::
::Unlikely, but there could be a short in the filament string to chassis ground.
::Lewis
:::
::
::
:
:
Thank you for all the welcome advice, I will pull the rectifier and see whats up.


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