Philco 37-670B power transformer question - Printable Version

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+--- Thread: Philco 37-670B power transformer question (/showthread.php?tid=13577)

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Philco 37-670B power transformer question - tiloco - 11-29-2015

Hi all. I am just finishing a restoration on a 37-670B. I have noticed that the power transformer seems to have been replaced. Looks like someone took the top cover off the original and put it on another core. (bottom of core reads LP 0290 C). I only read 58 ohms across the B+ secondary and about half of that from CT to each secondary lead (should be 128 ohms across the primary). The voltage chart on the schematic says I should read 380v across cap #88; I only get 334v. Consequently the grid voltages at the RF, Det/Osc, and IF amp tubes is only about half of what it should be (43 instead of 90v).  Original power transformer # is 32-7640. I am wondering if anyone has the voltage specs for this transformer as I cannot seem to find them anywhere. Also if anyone could recommend a suitable replacement, that would help. Thanks,
   Tim

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RE: Philco 37-670B power transformer question - Radioroslyn - 11-29-2015

The simple solution is the replace the rectifier toob with silicon diodes. This will raise your B voltage about 50v or better.

Terry

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RE: Philco 37-670B power transformer question - tiloco - 11-29-2015

(11-29-2015, 04:00 PM)Radioroslyn Wrote:  The simple solution is the replace the rectifier toob with silicon diodes. This will raise your B voltage about 50v or better.

Terry

Thanks Terry, The problem I have is that the voltages on the plates of the DET,RF, and IF AMP is already high (measured with a DVM). Voltages on the plates of the driver and output tubes is about 40v low. Screen voltages on the DET, RF, and IF AMP tubes is about half of what it should be. Will a SS rectifier help any, and if so, I am not sure how to wire one up?
Thanks for your input,
  Tim

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RE: Philco 37-670B power transformer question - Radioroslyn - 11-30-2015

Grab 2 1N4007's anodes go to the plate pins of the tube and both cathode goes to one of the filament pins.

Terry

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