Replacing Filament Transformer with NOS Thordarson

[fixmeplease]

1953 or 1954 Philco with wrong chassis, but the correct Sams for the chassis is 227-10.

Split chassis. i think the filament transformer was replaced as the part number is wrong. I can find nothing about that part number online. Anyway it has always gotten hot. I think a couple years ago I trouble shot it and narrowed it down to a problem with that transformer. Im betting it was for a lower amp model and thats why it gets hot.

Forward to the present, I found a NOS Thordarson 21F12 filament transformer, a 10 amp model, the correct sub. No paperwork was included.

The one I removed had 4 wires. I can see that 2 were primary and 2 were filament. My new one has 5 wires. On my new one Im assuming (please tell me if Im wrong) that the 2 black wires are primary. On the other side of the tranny are 3 wires. 2 outer are solid green and the center one is green striped. So which ones do I use? Thanks!

[Tim]

You can verify with a resistance check but the striped one will be the secondary center tap so use the 2 solid green and insulate the striped one so it does not touch anything.

[fixmeplease]

Thanks Tim!

[Yamamaya42]

Correct, the black wires are clearly primary, and before you set yourself up for any nasty surprises, you can always power it up out of circuit and measure the output

[Yamamaya42]

the more i think about it, the more i believe that you must be VERY SURE and careful before hooking it up, for I think not 100% sure, that that is REALLY a split phase 12 volt transformer, IE CT to chassis ground and 2 6.3 heater suply at 5a ( x and y ),, it would be REALLY bad if this were true

[Yamamaya42]

like seen here https://i.imgur.com/QwNcmU0.png

[dieseljeep]

Originally Posted by fixmeplease

1953 or 1954 Philco with wrong chassis, but the correct Sams for the chassis is 227-10.

Split chassis. i think the filament transformer was replaced as the part number is wrong. I can find nothing about that part number online. Anyway it has always gotten hot. I think a couple years ago I trouble shot it and narrowed it down to a problem with that transformer. Im betting it was for a lower amp model and thats why it gets hot.

Forward to the present, I found a NOS Thordarson 21F12 filament transformer, a 10 amp model, the correct sub. No paperwork was included.

The one I removed had 4 wires. I can see that 2 were primary and 2 were filament. My new one has 5 wires. On my new one Im assuming (please tell me if Im wrong) that the 2 black wires are primary. On the other side of the tranny are 3 wires. 2 outer are solid green and the center one is green striped. So which ones do I use? Thanks!

The label shows a 6 volt secondary with a CT, which means to use the green leads and insulate the striped one, as stated before.

[fixmeplease]

Got it hooked up and its working great. Thanks everyone! To confirm in case someone finds this doing a search the center wire was not used.