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That coil was open in both chassis. Same old issue. primary wound over a celluloid insulator that had hardened and warped.
Luckily, the break was easy to find and repair. I did not need to rewind 
[Image: https://live.staticflickr.com/65535/5163...6f90_c.jpg]
Yep, that fixed it. It must have been barely hanging on and would open up when it got warm.
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Hello Bob,
That is great news now the radio should work fairly well !
Sincerely Richard
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I performed a minor surgery on the Philco 20 PP speaker I have so that the field coil is connected to one end of the OT primary rather than the center tap.
[Image: https://live.staticflickr.com/65535/5164...3df9_c.jpg]
Viola - it works. Sounds a little hollow and dull, but it works fine. I'll use it for now until I can get the 90 speaker field coil repaired.
[Image: https://live.staticflickr.com/65535/5163...032d_c.jpg]
(This post was last modified: 10-29-2021, 05:03 PM by Bob Andersen.)
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Unless I missed it - does the field coil work now?
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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I have two speakers. A single ended one for a Philco 90 with an open field coil and missing output transformer.
The one shown above is for a Philco 20 with push-pull 71A driving it. I disconnected the center tap and tied one end of the output transformer to one side of the field coil to make it compatible with my 90.
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Hello Bob,
good thinking far as the speaker goes !
sincerely Richard
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I found a cheaper source of magnet wire, can't vouch for the seller of course: https://www.ebay.com/itm/363090262105
Regards
Arran
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Thanks for the tip. I just placed an order.
I'll try the techniques described in this thread to get the pole piece out and back in.
https://philcoradio.com/phorum/showthread.php?tid=15792
(This post was last modified: 11-03-2021, 01:12 AM by Bob Andersen.)
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Hey, finally found a currently made audio taper 500K pot with a 2" round shaft. 2W rating.
Not exactly cheap at $17.76, but at least there's an option from a decent brand. Shaft can be cut or filed down as needed.
https://www.mouser.com/ProductDetail/CTS...364R504A21
Also available from Digi-Key for a bit more.
https://www.digikey.com/en/products/deta...1/11617375
(This post was last modified: 11-03-2021, 10:35 PM by Bob Andersen.)
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Hello bob,
man I wish you were not in a hurry because when i visit my family in dec. i could check my NOS stock of controls .
sincerely Richard
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Oh, I'm not in any particular hurry. I might very well have one in my stash too. I've seen many radios with a replacement volume control of the wrong value or taper type. It's nice to have options.
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Magnet wire arrived today. Looks like the real deal. We'll soon find out how well it works.
[Image: https://live.staticflickr.com/65535/5165...512d_c.jpg]
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Hello Bob,
that is great news I do have some but I don't think that gauge thou.
I have a new project to rebuild a huge RCA like 10 tube count chassis with the magic brain .
Sincerely Rich
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I wish I had a magic brain. Mine is always thinking the wrong thing.
!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!
/\/\/\/\/\/\/\/\/\
[Image: http://philcoradio.com/phorum/images/smi...on_eek.gif] Chris
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The new volume control has arrived and works very well. Perfect fit too.
It's just temporarily wired in here as I still need to cut the shaft down.
[Image: https://live.staticflickr.com/65535/5166...9f2f_c.jpg]
I also installed the new arch support. Before gluing I painted with this very flat camo paint. It's a great match for the old dark interior wood.
[Image: https://live.staticflickr.com/65535/5166...c0c1_c.jpg]
The arch is far stronger now and that's a big load off my mind.
Sorry about the blurry photo. Bad lighting in the basement.
[Image: https://live.staticflickr.com/65535/5166...ef6f_c.jpg]
(This post was last modified: 11-10-2021, 02:22 AM by Bob Andersen.)
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