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47-1227 Output transformer
#1

I'm working on my first radio a Philco 47-1227 that was my bosses radio that he used when he was in high school. Unfortunately, I have no idea what killed the radio but my boss tells me there was dripping wax everywhere. The output transformer 32-8274 looks like it got very hot. I know nothing about transformer terminology but on one side there are three plastic coated wires a blue one, and orange one in the center, and a white one. Between the blue and orange leads I get a reading of 126Ohms and the schematic says I should get 275ohms, between the orange and white leads I get a reading of 142 ohms while the schematic says I should get 300. On the other side of the transformer are just two wires, one going to ground with no insulation and the other wire is lacquer coated and in a loose insulation sleeve. I get a reading of 0.47 ohms between these and the schematic says I should get 0.1. Are these readings way out of spec? I'm not sure how much variation is acceptable. If this transformer is fried can new ones be obtained? I'm in the process of completely recapping this radio. Once I get it close I know someone who can do the final calibrations for me. The input transformer had been replaced and some earlier time but the same person that will do the final calibration gave me a used original replacment. Again some of the windings are off from the specs and I don't know what's allowable.
Thanks,
Keith
#2

I did not look the set up and see if that is the correct part number for the original. If it is a replacement those resistance reading could be OK. Does the unit smell burned? Also measure between primary and core and see if shorted to core. The set probably has leaky caps and may have drawn too much current and overheated the output transformer. May have damaged the power transformer also.
#3

Sounds to me like the original has shorted turns and needs to be replaced.

According to Philco's 1957 parts catalog, you need one with a 9000 ohm primary impedance to match a 3.5 ohm voice coil (secondary). The same catalog says 15 watts which I believe is a mistake; push-pull 6K6 tubes have to be pushed really hard to get 10 watts output.

And as Jim pointed out, make sure that power transformer is still good! A lot of those 1946-47 Philco radio-phonograph consoles have burned out power transformers; this was apparently a weak spot in those models (46-1209, 46-1226, 47-1227, 47-1230).

--
Ron Ramirez
Ferdinand IN
#4

Thanks for the advice, I'll check the power transformer next. If I find that I need new transformers are there new replacements or do I need to find used ones?
Keith




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