Bad Output Transformer - Printable Version
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Bad Output Transformer - Eric T - 07-26-2012
Well I hit a snag on my 42-1008 project:
the output transformer (#73 part no. 32-8133) primary is reading 4.7Kohms on one leg to the center tap and 180 ohms from the other leg to center tap. The secondary is .6 ohms.
Does anyone have any suggestions on what to do about a replacement or substitute?
RE: Bad Output Transformer - John R - 07-26-2012
John Kendall at http://www.vintage-electronics.com/rjy.htm
has a 42-1008 chassis for parts. You would need to email him to see if he has the output transformer available. If not you could go the universal Hammond transformer route. Radio Daze sells these.
RE: Bad Output Transformer - Arran - 07-27-2012
Failed output transformers seem to be a common problem with early 40s Philcos, but the usual failure is an open primary not shorted turns. Have you disconnected anything tha may be connected in parallel to the primary? If it does turn out to be defective I would try to find a push pull output transformer from a parts set that is NOT an early 40s Philco or a new one, or an aftermarket NOS replacement. Harvesting one from another Philco chassis of the early 40s may be a wasted effort, you may end up with another dud that way.
Regards
Arran
RE: Bad Output Transformer - Eric T - 07-27-2012
The schematic shows the primary should be 220 ohms from center tap to one leg and 200 ohms from center tap to the other leg. It also says the secondary should be .2 ohms.
RE: Bad Output Transformer - Eric T - 07-27-2012
Does anyone know what I'm looking for in a replacement transformer? I have no idea what power rating, impedance, etc. that is needed for this application.
RE: Bad Output Transformer - Ron Ramirez - 07-27-2012
32-8133 specs:
Primary impedance 17,000 ohms center-tapped; secondary 5 ohms; 6 watts; turns ratio 58:1.
A Hammond 125C would be a good replacement. It looks like you would want to connect your speaker voice coil across either output terminals 1 and 3, or terminals 2 and 4 (whichever one gives greatest volume).
RE: Bad Output Transformer - Eric T - 07-27-2012
Thanks for the info, Ron. I really appreciate it.
