Posts: 46
Threads: 15
Joined: Jun 2017
City: Madison, WI
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...013332.pdf
Posts: 45
Threads: 11
Joined: Dec 2019
City: Oconomowoc
State, Province, Country: Wi
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.
Posts: 46
Threads: 15
Joined: Jun 2017
City: Madison, WI
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 ?
(This post was last modified: 12-08-2019, 08:58 PM by
Tucker.)
Posts: 7,248
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
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
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 46
Threads: 15
Joined: Jun 2017
City: Madison, WI
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 ?
Posts: 45
Threads: 11
Joined: Dec 2019
City: Oconomowoc
State, Province, Country: Wi
Hi Tucker,
Red wire takes the place of the Black and Tan wire, you should have 2 wires that go to the speaker.
Forrest