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Model 90 Output Transformer
Arran
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#6

03-03-2016, 05:20 AM
(03-02-2016, 03:52 AM)rrova Wrote:  I'm working on restoring a Philco Model 90 (2 45's for output, Min-max switch, March 1931). It was recapped but not working when I received it. I was not impressed with the quality of the previous work...

Lack of plate voltage to the first 45 (the second 45 is getting 243V at the plate) led me to look at the speaker output transformer wiring. I'm convinced that the wiring is not correct and also that the output transformer is bad. The transformer is a Jefferson Electric 2766J but I have no info on its wiring layout. Checking continuity between leads shows pretty much everything open. There are 2 end connection lugs on each side with center wires also on each side. One side has a black center wire, the other is red (or orange?). Does anyone have any info on which is primary/secondary and start/finish/center tap?

I'm looking at the Hammond 125C as a replacement for this transformer. Other threads lead me to believe it will work in this context.

I'd appreciate any advice!

 The existing transformer could also be miswired, the B+ should always go to the center tap of the primary, so it's worth disconnecting and rechecking. As for replacements pretty much any push pull output transformer should work, except if it's for 41/6K6 tubes, the primary impedances are pretty close between 45s, 47s, 42s/6F6s, 6V6s, 6L6s, and 6BQ5s, it isn't that critical.
Regards
Arran
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Messages In This Thread
Model 90 Output Transformer - by rrova - 03-02-2016, 03:52 AM
RE: Model 90 Output Transformer - by klondike98 - 03-02-2016, 08:07 AM
RE: Model 90 Output Transformer - by morzh - 03-02-2016, 09:29 AM
RE: Model 90 Output Transformer - by Radioroslyn - 03-03-2016, 02:19 AM
RE: Model 90 Output Transformer - by rrova - 03-03-2016, 04:53 AM
RE: Model 90 Output Transformer - by Arran - 03-03-2016, 05:20 AM
RE: Model 90 Output Transformer - by rrova - 03-04-2016, 06:05 AM
RE: Model 90 Output Transformer - by morzh - 03-04-2016, 10:34 AM
RE: Model 90 Output Transformer - by rrova - 03-04-2016, 05:43 PM
RE: Model 90 Output Transformer - by morzh - 03-04-2016, 07:32 PM
RE: Model 90 Output Transformer - by rrova - 03-04-2016, 08:37 PM
RE: Model 90 Output Transformer - by morzh - 03-04-2016, 09:24 PM
RE: Model 90 Output Transformer - by rrova - 03-04-2016, 09:53 PM
RE: Model 90 Output Transformer - by morzh - 03-04-2016, 09:58 PM
RE: Model 90 Output Transformer - by rrova - 03-04-2016, 10:07 PM
RE: Model 90 Output Transformer - by Tubesforme - 03-08-2016, 03:41 PM
RE: Model 90 Output Transformer - by rrova - 03-05-2016, 04:01 AM
RE: Model 90 Output Transformer - by Radioroslyn - 03-05-2016, 08:06 PM
RE: Model 90 Output Transformer - by rrova - 03-05-2016, 08:53 PM
RE: Model 90 Output Transformer - by morzh - 03-05-2016, 08:53 PM
RE: Model 90 Output Transformer - by Radioroslyn - 03-05-2016, 10:35 PM
RE: Model 90 Output Transformer - by morzh - 03-05-2016, 11:15 PM
RE: Model 90 Output Transformer - by rrova - 03-07-2016, 02:47 AM
RE: Model 90 Output Transformer - by morzh - 03-08-2016, 03:51 PM
RE: Model 90 Output Transformer - by rrova - 03-08-2016, 06:17 PM
RE: Model 90 Output Transformer - by Tubesforme - 03-09-2016, 10:59 PM
RE: Model 90 Output Transformer - by rrova - 03-09-2016, 11:04 PM
RE: Model 90 Output Transformer - by Tubesforme - 03-12-2016, 05:47 PM
RE: Model 90 Output Transformer - by Tubesforme - 03-10-2016, 08:35 PM
RE: Model 90 Output Transformer - by morzh - 03-08-2016, 06:50 PM
RE: Model 90 Output Transformer - by rrova - 03-09-2016, 05:33 PM
RE: Model 90 Output Transformer - by morzh - 03-09-2016, 05:39 PM
RE: Model 90 Output Transformer - by morzh - 03-10-2016, 11:33 AM
RE: Model 90 Output Transformer - by morzh - 03-10-2016, 09:19 PM
RE: Model 90 Output Transformer - by rrova - 03-11-2016, 01:06 AM
RE: Model 90 Output Transformer - by morzh - 03-11-2016, 10:36 AM
RE: Model 90 Output Transformer - by Arran - 03-13-2016, 05:31 AM



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