40-180 Output Transformer - Printable Version

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+--- Thread: 40-180 Output Transformer (/showthread.php?tid=20703)

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40-180 Output Transformer - Tucker - 12-07-2019

The audio output transformer on my 40-180 looks like it's been getting rather warm so I decided to replace it as long as I'm recapping the set.  I went with a Hammond 125C universal push pull transformer but I'm not sure that I understand the wiring diagram correctly. It appears that I would connect the secondary to pins 4&6 to get 12,800 impedance with an 8 ohm speaker.
The existing transformer appears to only have one primary wire coming from the power transformer. The Hammond has 3 wires on the primary side, a red, a blue, and a brown wire.  Not sure how that works ?
 
Here's a link to the transformer;  http://www.hammondmfg.com/125.htm 
 
And the schematic info;  http://www.nostalgiaair.org/PagesByModel/332/M0013332.pdf

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RE: 40-180 Output Transformer - Forrest - 12-07-2019

Hello Tucker,
Blue and brown go to each of the 41 output tubes red goes to the po wer supply 2 and 4 go to 8 ohm speaker.

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RE: 40-180 Output Transformer - Tucker - 12-08-2019

Well, I just looked at the 4 wires under the existing output transformer and they are ;

Black - goes to pin 2 of a 41 tube

Tan - goes to pin 2 of the other 41 tube

Black/Tan striped - goes to a terminal strip lug that splits off to pin 2 of the 7C6 tube and pin 3 of one of the 41 tubes and it also connects to one of the filter caps.

Bare wire - goes directly to the speaker.

I'm wondering if I wouldn't use the red wire for this radio ?

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RE: 40-180 Output Transformer - Radioroslyn - 12-08-2019

Got to use the red wire it goes to pin 3 of the 41. With out it you won't have any hv on the plates of either 41 tube

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RE: 40-180 Output Transformer - Tucker - 12-08-2019

I think I’m missing something, the existing transformer has 4 wires and the replacement has 5 wires. Does the red wire replace the striped wire ? And does one of the wires to the speaker get connected to the same place the red wire gets connected to ?

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RE: 40-180 Output Transformer - Forrest - 12-09-2019

Hi Tucker,
Red wire takes the place of the Black and Tan wire, you should have 2 wires that go to the speaker.
Forrest

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