The PHILCO Phorum
Model 50A rebuild - Printable Version

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Model 50A rebuild - Mtmattking - 04-08-2024

I have been out of this hobby for many years.

1st question:  when I replace the Bakelite enclosed Bypass Condensers do I just install a simple capacitor (with the correct Mfd, of course) by swapping out the Bakelite device?

Thank you

RE: Model 50A rebuild - GarySP - 04-08-2024

Welcome to the Phorum, Mtmattking! The bakelite enclosures are fairly easy to gut and refill with new caps. You don't have to repot with glue since they wont be seen being mounted against the chassis. Several others have documented their rebuilds. I'm sure they will chime in. Take care and BE HEALTHY! Gary

RE: Model 50A rebuild - morzh - 04-08-2024

>>with the correct Mfd, of course

And correct Working Voltage.

RE: Model 50A rebuild - Mtmattking - 04-08-2024

They are hallow? I will pull one off and check it out. Thank you.

Follow up question: the schematic wants me to pair a capacitor (#25) and a resistor (#22). Do I just wire them in parallel?

Also, on three separate schematics I have 3 different capacitor ratings in the Filter Condenser Block (line 1 starts with .15Mf, or ,.15Mfd or .1Mfd. Any idea which block is correct? I have a Canadian Model 50A but I want to change to 50 cycles.

Thank you

RE: Model 50A rebuild - Mtmattking - 04-08-2024

OH, and what would the correct working voltage for all these caps?

RE: Model 50A rebuild - klondike98 - 04-08-2024

If you use 630v polyester film caps you will be fine. I often get mine from Antique Electronic Supply but there are many other sources.
Mike (morzh) did a nice tutorial on those bakelite block caps.

See: https://philcoradio.com/library/index.php/shop-talk/techniques/bakelite-capacitor-rebuild-without-desoldering/
in our library.

RE: Model 50A rebuild - Mtmattking - 04-08-2024

Thank you !

RE: Model 50 Capacitor values - Mtmattking - 04-08-2024

/I have found 3 different list of specs. For the 50–60cycle block. The one above starts at 0.1Mfd. Another starts at .15 and another starts at .5. Which is best?

RE: Model 50A rebuild - klondike98 - 04-09-2024

I moved your question back to your 50 restoration thread to keep all your discussions together. It makes it easier for people to follow and help you.

I’m not sure which lists you are referring to but this annotated schematic should answer your question
https://philcoradio.com/library/images/schem/50.jpg

RE: Model 50A rebuild - Mtmattking - 04-09-2024

Thank you. I did not know one could merge. This keeps things smoother.

RE: Model 50A rebuild - morzh - 04-11-2024

As Bob has noted, 630V is the one, and it is the most popular WV for axial polyesthers (also 500V sold in the AES, but to have them universal for just about every possible place, 630V is better).

RE: Model 50A rebuild - Mtmattking - 06-29-2024

I need to rebuild the heat shield in my Model 50 that curves over the three tubes on the right side (viewed from the back of the set).

Does anyone have a template for the shield?

Thank you.  Matt

RE: Model 50A rebuild - morzh - 06-30-2024

When you said "heat shield" - did you mean the sectioned sheet metal thingy around the 24A tubes on the left side of the chassis, when looked from behind?

RE: Model 50A rebuild - Mtmattking - 06-30-2024

Yes, it is curved over the top of the tubes

RE: Model 50A rebuild - morzh - 06-30-2024

It is not a heatshield. It is a multi-tube EM shield. It simply shields the tubes, usually the 24A ones, in radios like 20, 50, 70 or 90, from affecting each other.
If not shielded, the tubes will interact and the radio possibly squeal.

This said, there are repros available by more that one vendor. I know Chuck Paci made those.
Mark Oppat (Oldradioparts) is another guy. And in one of his old posts he mentioned a 20 shiled might work for 50. Can't say if this is true, but you could ask. He said that because he did not manufacture the one for 50, but did make 20/70/90 ones.