The PHILCO Phorum
37-670 - bakelite block discrepancy - Printable Version

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37-670 - bakelite block discrepancy - Tom Hamilton - 04-02-2014

Hi,

I am slowly doing a restoration on my 37-670 console and find that there's a discrepancy between what my radio has and what the schematic says. From what I understand, this is something Philco did a lot.

My schematic gives part #71, a .015 mfd dual bakelite block, a part number of 3903-LU. According to the Philco Service Bulletin No 289 the capacitors in that 3903-LU block are .01 and .006.

However, my actual radio has for part #71, a 3793-DU bakelite block that appears to have been installed by the factory. The No 289 service bulletin for that block calls for two .015 mfd capacitors.

I could be mistaken, but I think the capacitors in this bakelite block are somehow related to the tone control.

I've got my schematic and service information from Chuck Schwark and there's no mention of any change.

I guess my question is, should I go with what the schematic says and install some .01 and .006 capacitors or install what the part number on my actual bakelite block calls for, two .015 capacitors?

Thanks a lot for your help.

Tom

RE: 37-670 - bakelite block discrepancy - raydog - 04-02-2014

If you have a way to check caps, you could always take a reading of the bakelite caps and see what they are so you can verify what you have.... assuming they are still good. Was the radio functioning when you started?

RE: 37-670 - bakelite block discrepancy - Carl Travis - 04-02-2014

Looks like the P/N was a misprint on the parts list.
Schematic also shows it as a dual .015.

RE: 37-670 - bakelite block discrepancy - Tom Hamilton - 04-02-2014

Raydog and Carl, Thanks a lot for the quick answers.

Raydog, I don't really have a way to check the capacitors in the block and no, this radio wasn't working when I got it. I still haven't plugged it in to try it. I probably could now as I've already replaced all the electrolytic and almost all of the paper and bakelite block capacitors.

Carl, I did notice the schematic shows two .015 capacitors for # 71 so I'm inclined to consider the bakelite block (part 3793-DU) that I've actually got in my radio as being correct. That bakelite block uses two .015 capacitors.

Thanks again,
Tom

RE: 37-670 - bakelite block discrepancy - codefox1 - 04-02-2014

Couldn't be a show stopper either way if you can't find better information.

RE: 37-670 - bakelite block discrepancy - Jamie - 04-03-2014

I'd go with the two .015 caps. The chances of them messing up the printed parts list are a lot higher than them actually putting the wrong caps inside the bakelite block, or installing the wrong block at the factory.

RE: 37-670 - bakelite block discrepancy - codefox1 - 04-03-2014

Agree, Follow schematic. In any case as suggested before certainly not harmful.

RE: 37-670 - bakelite block discrepancy - Tom Hamilton - 04-03-2014

PuhPow and Codefox1,

Thanks a lot for the advice. I plan on following your advice by installing two .015 caps in this block.

Tom

RE: 37-670 - bakelite block discrepancy - Tom Hamilton - 04-15-2014

Hi,

I am doing a followup on my radio to let you all know where I'm at.

I did replace the two capacitors in the bakelite block (part #71). The interesting thing is that the two capacitors I removed from this bakelite block have different numbers on them leading me to believe that this block had two different capacitors installed. However, I did go with the schematic information and installed two .015 capacitors in this block.

The good news is that I finally gathered up my courage, plugged in and powered up this radio. It works! I listened to the Dodger game for awhile. The tone control, which, I understand, uses the above mentioned bakelite block, seems to work very well.

I still have to replace the four capacitors in the RF deck and do one more bakelite block, but my radio is now working again for the first time in many years. I'm thrilled, to say the least.

Tom