I'm restoring a 41-250 with nearly identical symptoms as those posted Feb. 5 by another user. Only a limited span of BC band is available, frequencies are off and can't be aligned, Police band has only a strong local BC station on it, no shortwave. Pushbuttons don't change stations. I've rewired chassis and band switch, all tubes check strong, etc, etc, no significant change in symtoms from before to after. All oscillator coil windings check good, all wiring checks correct per schematic. I'm wondering whether oscillator issues is common in this model for some reason. If I have the corrosion issue in the oscillator coil it doesn't show in impedance checks. Any help appreciated - I'm at wits end, having spent weeks on this one!
Posts: 13
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Joined: Dec 2007
I am the guy with the other Philco. I will take it out of the radio today or tomorrow and check it for shorted windings. Continuity readings will not find a shorted turn so I will test it on my Sencore Z meter using its ringing test. I will let you know if its bad.
BTW, my coil has a green streak of corrosion that can be seen through the wax.
I have a thread going over on the antique radio forums about coil winding if you are interested.
http://www.antiqueradios.com/forums/view...hp?t=83495
Thanks. Mine had extensive work prior to me, and it's now obvious he twisted every screw in sight. By doing likewise last night, I'm now able to receive all bands although sensitivity is sub-par. I'll do a full alignment and that should take care of that. Pushbuttons still don't change stations, though - I don't even hear background noise on the pushbutton setting. I replaced those two 370pf caps that supposedly affect pushbutton tuning (c20, c20A I think) but to no avail.
Posts: 13
Threads: 5
Joined: Dec 2007
I replaced that cap on mine. Half was open and half was ok. Didn't help.
I will let you know how it turns out.
BTW, I am in Denison, 40 miles north of you.
Posts: 13,776
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City: Ferdinand
State, Province, Country: Indiana
Sometimes baking a coil in the oven will help, in that baking eliminates moisture that the coil has absorbed over the decades.
Bake it at 175 to 200 degrees for a half-hour or so, with the coil sitting on edge; DO NOT lay it down on its side.
After baking, seal the coil with a few coats of lacquer. DO NOT use wax to reseal the coil, even though Philco used wax originally! When these sets were new, it was thought that wax would keep moisture out. It doesn't. In fact, wax will not only allow moisture in, but it will serve to KEEP moisture in!
I have a 40-201 on the bench now, with tracking issues. 1280 kc comes in at 1420. I suspect the oscillator trimmer assembly, as the high end AM trimmer is tight, and the mounting is loose. It's been forced before. Wonderful...
Tom, on your pushbutton assembly, have you cleaned it? You may have to remove, spray the contacts with tuner cleaner and brush them with an old toothbrush while the cleaner is still wet. Those contacts are notorious for going intermittent/bad, but usually they respond well to a good cleaning. And always replace both 370 pF caps with new mica units (I see you have already done this).
--
Ron Ramirez
Ferdinand IN
Ron, thanks for the tips and reassurance; this is a great site. I cleaned the pushbutton switch assembly as you said but it was very dirty indeed, so I'll go back and be certain I was thorough. Tracking was an issue on my 41-250 as well - tracking high as you describe for the one you have on the bench. But then the IF alignment was so far off it's difficult to assign causes for each performance issue I see. I now note on my 41-250 the shortwave antenna trimmer on the back apron has precisely zero affect on the shortwave band - yet another mystery I need to solve. This old unit had many simultaneous problems but I'm slowly working through it. I love basket cases and this one has provided many, many hours of entertainment. That's what it's all about anyway, isn't it?
Electroubleshooter, thanks for the input on solving your 41-250 issues. Every little bit helps - also, it's good to know there is someone to commiserate with in the neighborhood - 30 miles isn't much when it comes to radio is it? Please post your discoveries and I'll do likewise so maybe others working this model will have a leg up on some of the common problems. This isn't one of the easiest radios I've worked on but it has been educational. Like verifying correct oscillator coil hookup when you can see all contacts have been re-soldered. How about that coil diagram on the schematic?
