Philco model 20 BC resistor - Printable Version
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Philco model 20 BC resistor - Radioroslyn - 03-02-2011
Was wondering does it run pretty hot near the B+ end? Mine does. Seems like it been doing it for along time. It's melted some of the tar from the filter bank on to it and the chassis and on to the resistor. Voltages look good and it plays ok too. After it's been on for a few minutes if I look closely I can see the tar that has leaked on to it bubble.
Terry
Re: Philco model 20 BC resistor - Chuck Schwark - 03-02-2011
Just remember, you're running the radio with today's 120-125 VAC and the set was designed for 110-115 VAC back in the day.
The power transformer will be pumping out a higher secondary voltage.
Not real good for the longevity of the power transformer in the long run.
Use a buck/boost transformer to lower your AC voltage or a variac and see what the effects are. The BC resistor should get relativelt hot, since it's a wirewound type, but not 'boiling' hot. Your higher AC mains voltage may be a contributor.
Chuck
Re: Philco model 20 BC resistor - Radioroslyn - 03-02-2011
Have got a autotransformer hook up to it now. Running it at 90v gets warm but not bubbling.
Tnx
Terry
Re: Philco model 20 BC resistor - Radioroslyn - 03-02-2011
What I may do is remove the input capacitor so the p/s is choke input. That will drop the output voltage down.
Terry
Re: Philco model 20 BC resistor - Ron Ramirez - 03-03-2011
Terry, you posted in another thread that replacing the 0.25 uF bypass caps helped lower your B-C resistor's fever; is it doing OK now?
I have a plain 20 and a deluxe 20, neither one are restored so I can't comment on how warm the B-C resistor gets. But I would not expect them to get hot to the point of roasting under normal operation.