Philco 20 hum after restoration - Printable Version

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+--- Thread: Philco 20 hum after restoration (/showthread.php?tid=1716)

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Philco 20 hum after restoration - retiredinprescott - 02-23-2009

I have completely recapped a Philco 20 and also replaced all out of spec resistors. Radio played fine with no hum. Then I replaced the 4 speaker wires going from speaker to speaker plug. Two go across field coil and two go to primary of output transformer. The original wires were badly frayed and twisted together along their length. I did twist the new wires around each other but in no particular order. Now the radio has a constant hum (not very loud but noticeable) which does not vary with volume control setting. Can anyone shed any light on this for me? Radio still plays fine but the hum does annoy me.
Thanks

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Re: Philco 20 hum after restoration - rickd - 02-23-2009

One of the two leads to the speaker field also goes to the ct of the op transformer primary. Any chance these two got reversed?

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Re: Philco 20 hum after restoration - retiredinprescott - 02-23-2009

I had all the leads numbered on both ends before I removed them but I will check that out.
Thanks,

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Re: Philco 20 hum after restoration - retiredinprescott - 02-23-2009

rickd Wrote:One of the two leads to the speaker field also goes to the ct of the op transformer primary. Any chance these two got reversed?

You were right on! Somehow, despite all my labeling, I must have switched those two leads. The set plays fine now with only the slightest hum when not on a station. Thanks for the good advice

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