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Philco 38-15CS
#9

Congrats Andy! If you found an"open" between the OPT (Output transformer) andthe plate of the 41 at the socket, that may explain the high plate voltage. One time I found an open output transformer by watching the inside of the tube glow a lot brighter. It was the screen grid getting too hot, hot enough to glow. However, with the cathode connection open, strange to find that the plate was high and the screen was normal, as with the cathode connection open, there should have been little current. Wonder if some of the readings caused mechanical disturbance that affected them. The Screen is fed by the same level of B+ that the OPT, therefore the readings should be the same or the plate slightly lower.

Glad you got it working. Infortunately, the speaker wiring colors don't match the schematic. Based on your pic, the white should go to the 41 plate. The Green appears to be the output of the filter, so should go to the main B+. The black wire should go to the 84 rectifier tube cathode. If the green and black are reversed, audio level will be lower, B+ and hum levels are likely to be higher.

When observing the OPT, not theat there are 3 connections. The OPT connections are on one side, the lone Field connection from the Rectifier Cathode is on the other side by itself. The connection that is only to the primary winding goes to the Output tube plate. The connection that is both the OPT Primary and has a field connection is the Radio B+ (Output tube screen, B+ to rest or radio). The connection on the other side of the transformer, for the field coil only, is from the cathode of the Rectifier.. Phasing of these connections is also important. If there is too much hum, it is possible that some of these connections were reversed. If the phase of the hum bucking coil or field coil are reversed, hum will be greater.

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55


Messages In This Thread
Philco 38-15CS - by AVSorrell - 08-30-2022, 05:47 PM
RE: Philco 38-15CS - by Radioroslyn - 08-30-2022, 07:41 PM
RE: Philco 38-15CS - by MrFixr55 - 08-31-2022, 05:35 PM
RE: Philco 38-15CS - by AVSorrell - 08-31-2022, 07:09 PM
RE: Philco 38-15CS - by Radioroslyn - 08-31-2022, 09:29 PM
RE: Philco 38-15CS - by AVSorrell - 09-01-2022, 08:46 AM
RE: Philco 38-15CS - by Radioroslyn - 09-01-2022, 10:39 PM
RE: Philco 38-15CS - by AVSorrell - 09-02-2022, 05:33 PM
RE: Philco 38-15CS - by MrFixr55 - 09-03-2022, 01:19 PM
RE: Philco 38-15CS - by AVSorrell - 09-05-2022, 09:49 AM



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