The PHILCO Phorum

Need to know how to rebuild or replace BC Resistor in model 89 code 123. I am using a Rider schematic. Part #32 32 ohms and part #33 235 ohms. I have retired and trying to learn vintage radio repair. Thanks for your help.

Why do you think it needs to be replaced?
Terry

Hi,

If the BC resistor is open, it can be replaced with separate resistors. If only one section is open, only that section need be replaced. I would unwrap the bad section, just to make sure it doesn't "heal" at a later time, then connect the new resistor to the lugs of the old one. Ten watt resistors should do it. Someone else may chime in on that.

Steve

7estatdef Wrote:Why do you think it needs to be replaced?
Terry

Thanks for your reply. The B+ voltage was 475. The resistor was very rusted and the resistance would not read stable. When I tried to clean the resistor the wire fell apart.

Agreed, if a section is open you can sub a 10 watt sand resistor dressed against the chassis and use the existing lugs as mounting terminals. But if there is a short to the chassis, or evidence ore arcing, drill the candohm out and replace all the sections. You can use one or both of the rivet holes to mount a terminal strip. Again, dress the replacements up against the chassis to help disperse heat.

Of course if there was a problem with this rather hardy component I would certainly suspect the filter capacitors, which you should replace before powering up again. Actually all the paper capacitors as well, and any other resistors much above spec.

Thanks, I will try the 10 watt resistor.
Brown

I am still working on Model 89. I have it working up to IF tube. Using signal generator I can hear signal at signal grid of IF tube but cannot hear signal at begining of 1st IF transformer#18. Could the compensating condenser #19 be the problem and how do I test it. I am using schematic dated July 15, 1934. Cannot hear signal at plate of 36 tube either.
Thanks for your help.