[Ronin61]

Philco model 645 cap can part number 30-2114-m (2-1-2) bottom color code. Red-yellow-silver. Which one is the 1 MFd capacitor?

[ipwizard]

Hopefully someone will chime in.

You might have to trace them down with the schematic to find out for sure which cap goes to what lug on the e-cap.

[Ron Ramirez]

No way to tell from what you have given. I looked in one of the prewar Philco parts catalogs and it only gives the capacity and working voltage, not the color code.

As IPwiz said, trace it out on your schematic.

[ipwizard]

Maybe it's me but looking at the schematic I don't see a e-cap with that part number. The only multisection e-cap is #51 (p/n: 30-2080). It is a dual 1uf, and single 2uf.

You sure you have the right model number?

Schematic:
http://www.nostalgiaair.org/PagesByModel...013822.pdf

[Ronin61]

Your right about the schematic but it seems to have been changed to the part number I gave in my post. I went by the schematic and put the proper 2-1-1 caps. Thanks for looking out for me I'm really new at this but learning everyday. Turns out I have a bad 6a7 tube with one on the way. I believe the 6a7 tube has a important function.

[ipwizard]

You are correct about the 6A7 being important. It is your Oscillator, and the Detector for the radio. If that is bad the radio isn't going to play.

[Arran]

You don't have to do this of course but I would recommend replacing the three sections 1, 1 and 2 mf or 2-1-2mf, in that can with non polarized poly film caps rather then electrolytics. They cost somewhat more then the electrolytic equivalents but they make for a more permanent repair.
Regards
Arran

[klondike98]

recommend replacing the three sections 1, 1 and 2 mf or 2-1-2mf, in that can with non polarized poly film caps rather then electrolytics.

Arran, I seem to be asking you "why" today. Why would the poly film caps be better, I thought you had to use electrolytics to replace electrolytics? Thanks.

[morzh]

There is nothing that great about electrolytics. They simply were (and still are) the bighest energy per volume capacitive storage. Today there are better choices when the capacitance is not too large.

[klondike98]

OK, thanks morzh.

[Ronin61]

I went with the polorized caps before I read this but thank you for all the great input. Still waiting on the 6a7 tube that should bring this radio to life. Once the chassis is complete I will need help on the cabinet which has minor issues. I will post pictures of the cabinet in a few days.

[Art Hoch]

@Klondike,
Me too.

[Arran]

Electrically most circuits don't care if you use a non polarized capacitor in place of an electrolytic capacitor, the only things that matter are the voltage ratings and the capacity in microfarads. Since polyester film capacitors are relatively compact and inexpensive there is an advantage in using them in some places over an electrolytic capacitor when you can. At the time these sets were made non polarized caps meant paper and foil, which meant bulk, an electrolytic capacitor was substantially cheaper and more compact for the same capacity and voltage. Good quality electrolytic capacitors have maybe a 30-40 year lifespan, China crap brand caps last maybe 5 if you are lucky, polyester caps could last indefinitely barring manufacturing flaws, overvolting, or excessive heat.
Regards
Arran