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Candohm Resister Help - Printable Version

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+--- Thread: Candohm Resister Help (/showthread.php?tid=21846)


Candohm Resister Help - Fredmann99 - 11-23-2020

Greetings All,

This is my first post to this site and I am hoping someone can help me finish my Philco 20 restoration project.  I have repacked all the Bakelite blocks, replaced all the resisters, repacked the filter can, fabricated a dial lamp bracket, refinished the cabinet and replaced wiring as needed. The only thing left is this one resister.

My problem is the resister (see photo - grey ) that attaches to terminal 1 of part 25 and terminal 1 of the filter can. Terminal 1 of 25 attaches to terminal 5 of part 24 (transformer).

The resistor has the number 33-3280-1 stamped on it. I have found 33-3280 info which calls for 128 ohms but no wattage. Since these early numbers can be random in nature I am not sure of the resistance or wattage. Since this was probably added later (or different model) it does not appear on any of my schematics. To be honest, my ability to decipher this info using Ohm's Law, is unreliable.

I would appreciate knowing the ohm and wattage for this resister.

Thank you,
Fred    

RE: Candohm Resister Help - morzh - 11-23-2020

This Candohm is not native to the radio.
The part (probably the dead section of the wirewound part) is 1,400 Ohm.
At 18mA per tube (total 36mA) the dissipated power is 1.8W.
You might want to use 5W and up resistor.

RE: Candohm Resister Help - radio1 - 11-23-2020

Measure the ohms from the base of where that gray resistor (that someone added) attaches and to the candohm post that goes to ground - scrape deep into the metal at that post and also the base where the gray resistor attaches. What does it say?

RE: Candohm Resister Help - morzh - 11-23-2020

I am not sure I understood. Are you suggesting I do the scraping and measuring?

RE: Candohm Resister Help - Fredmann99 - 11-23-2020

Guys, that was really helpful. I was wondering why I couldn't get a reading (obviously to all but me) that the posts were too corroded. The push-pull transformer had been replaced. It's an "official replacement part" so possibly, there was a problem with the set that affected the last section of the long resister, part 25 (as you suggested). I will check the ohms tomorrow and go with a suitable replacement resistor at 5 watts. Unless you guys have any additional suggestions, I'll leave it at a greatful thanks for your help. Fred

RE: Candohm Resister Help - morzh - 11-23-2020

Let us know how it turns out.

This very resistor burning out in 20 is a popular thing to happen - my first 20 lowboy had exactly the same (and the only one) section open.
And the output transformer primary open. I guess it goes hand in hand.

RE: Candohm Resister Help - Fredmann99 - 12-01-2020

All,
I have not forgotten to post my final radio pics BUT I seem to have a new problem. It's a garble problem. I replaced the resistor noted above and (I don't think it's related - tried returning old part - then new part grounded to chassis - finally new part as noted above - no difference) now have a poorer reception with a slight garble. While I believe I have sufficient antenna attached I still get some variation when touching the volume control and get static when the chassis is grounded. I have checked all my solders and "poked" around with a chopstick for change but see nothing out of place. I would appreciate suggestions.

Fred

RE: Candohm Resister Help - morzh - 12-01-2020

Have you tried to align the set?

RE: Candohm Resister Help - Fredmann99 - 12-01-2020

No. I understand that special equipment is needed. Could it be a ground or a better antenna is needed?

RE: Candohm Resister Help - Arran - 12-03-2020

Not really, a Philco 20 used what was known as TRF circuit, basically the only thing you can do is adjust trimmer/padder condensers for gain, I don't think it even needs a neutralization adjustment since it uses screen grid tubes for RF amplifiers #24s or #35s. I'm not sure how you can get the dial to track on one of these, the factory instructions would probably say.
Regards
Arran