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Philco model 70 rebuild - by Tim P.
#3

After some initial checks (not powered), here are some findings: The RF coil(#6) seems to have an open primary winding, like Morzh's. So far, all the other (IF) coils check ok. The large wire wound resistor checks out ok, as do the power trans HV & primary. I havent pulled the tubes yet to check the fil. windings. The choke also checks out. So far, aside from tubes being replaced, the only repairs I have seen have been a cap replaced on one block, and looks like the volume control has been serviced or replaced.

Mike, my resistor has the 2nd tap going to ground like yours, so we have the same (early, I believe) version. I have never wound a coil before. It sounds simple, but any tips would help greatly. Do you know what gauge wire to use (and where to purchase), and the number of turns - in case I mis-count? I havent removed the coil yet, but it looks like the lower and smaller winding.

I think I read somewhere that the lower value (Pf) mica caps are ok and wont need replaced. Also, those large metal rectangular cans under the chassis, a .5 and .25 (also seem labeled wrong on the websites sch.) are just common caps? Anything I should know about restuffing these? Before I order the caps, are there any reccomendations? I read not to go too big on the power supply elect's, they are both 6mf, so about the closest I have found is an 8mf, double, or a 10mf single. The paper caps I am planning to order those little yellow tubulars from AES. I certainly understand replacing those .015 line caps before I power up - seen those on other radios pop! Just curious, what purpose will the 100k or 1meg resistor on the filter serve?

If I could find the place called "Somewhere", I could find "Anything" Icon_confused

Tim

Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44


Messages In This Thread
Philco model 70 rebuild - by Tim P. - by TV MAN - 01-29-2014, 10:46 AM
RE: Philco model 70 rebuild - by Tim P. - by TV MAN - 01-30-2014, 10:59 AM



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