Model 90 w/ one 47 tube cap question - Printable Version
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Model 90 w/ one 47 tube cap question - WyTex - 02-12-2023
Hi guys. Working on model 90 with the single 47 tube.
https://philcoradio.com/library/download/service%20info/wiring%20diagrams/vol1/split/Part54-Philco%20Wiring%20Diagrams%20Vol.%201.pdf
All bakelite blocks are rebuilt and have opened up part #30, Condenser block with 254k and 105k caps. In the attached pic it looks like 3 caps? 3 wires plus the ground to the tin can. I'm unsure how these are replaced. Did Philco use two caps for the 1 mfd which would be the 2 on the bottom and the 254k on top?
RE: Model 90 w/ one 47 tube cap question - Ron Ramirez - 02-12-2023
Paul
Unfortunately, you've been caught by the error in the Model 90 schematic with a single 47 output tube. This error is described at the following link:
https://philcoradio.com/library/index.php/shop-talk/model-notes/error-in-model-90-service-info-1-47/
Capacitor bank (30) actually has three capacitors inside - 0.1 uF (104K), 0.25 uF (224K or 254K), and 1 uF (105K).
If your original part (30) still has its original wire colors, you will see that one end of the 0.1 uF goes to the green wire; one end of the 0.25 uF to the white wire; and one end of the 1.0 uF to the black wire. The other ends of the three caps are tied together and connected to the can via the skinny ground wire.
When you get to can (24), you will likewise find it has but three caps inside (instead of four), All three are 0.25 uF.
A corrected schematic showing the proper part numbers may be found here:
https://philcoradio.com/library/images/schem/90b.jpg
RE: Model 90 w/ one 47 tube cap question - WyTex - 02-12-2023
My gosh. Thank you very much Ron!
Paul