Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

Hello, just thought i would add that the transformer is numbered "21" in the schematic.

:Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

Hi Sean

You got it right. Item #21 is an audio interstage transformer with center tapped secondary. Sometimes it's called a driver transformer. You can use a transformer similar to A-53C or AES #P-T156. Be sure your replacement has the center tapped secondary.

Norm

:Hello, just thought i would add that the transformer is numbered "21" in the schematic.
:
::Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

so then the 71a blew the filament out normally as in it just failed or is there a problem elsewhere that could have caused it to go bad

:Hi Sean
:
: You got it right. Item #21 is an audio interstage transformer with center tapped secondary. Sometimes it's called a driver transformer. You can use a transformer similar to A-53C or AES #P-T156. Be sure your replacement has the center tapped secondary.
:
:Norm
:
::Hello, just thought i would add that the transformer is numbered "21" in the schematic.
::
:::Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

Yes I did use the pt 156, thats why I thought that might be the problem....that I had the wrong type of transformer installed which blew out the filament of one of the 71a tubes. it does have a center tap on it.

:so then the 71a blew the filament out normally as in it just failed or is there a problem elsewhere that could have caused it to go bad
:
::Hi Sean
::
:: You got it right. Item #21 is an audio interstage transformer with center tapped secondary. Sometimes it's called a driver transformer. You can use a transformer similar to A-53C or AES #P-T156. Be sure your replacement has the center tapped secondary.
::
::Norm
::
:::Hello, just thought i would add that the transformer is numbered "21" in the schematic.
:::
::::Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

He Sean

Changing the transformer shouldn't cause a 71A filament to blow. Does the tube pins make good contact? Try resoldering the two large tube pins.

Any chance secondary of your transformer was connected to B+ rather than negative? This would make the grid positive, causing your 71A to draw high current. Doing this could blow the filament.

Norm

:Yes I did use the pt 156, thats why I thought that might be the problem....that I had the wrong type of transformer installed which blew out the filament of one of the 71a tubes. it does have a center tap on it.
:
:
::so then the 71a blew the filament out normally as in it just failed or is there a problem elsewhere that could have caused it to go bad
::
:::Hi Sean
:::
::: You got it right. Item #21 is an audio interstage transformer with center tapped secondary. Sometimes it's called a driver transformer. You can use a transformer similar to A-53C or AES #P-T156. Be sure your replacement has the center tapped secondary.
:::
:::Norm
:::
::::Hello, just thought i would add that the transformer is numbered "21" in the schematic.
::::
:::::Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?

Actually, the tube didnt blow out right away, it played for about 5 minutes. I did connect the new transformer wires to the old ones. I left a little of the old wire still soldered to the original location and just spliced in the new transformer so I would make sure it got connected correctly.

:He Sean
:
: Changing the transformer shouldn't cause a 71A filament to blow. Does the tube pins make good contact? Try resoldering the two large tube pins.
:
: Any chance secondary of your transformer was connected to B+ rather than negative? This would make the grid positive, causing your 71A to draw high current. Doing this could blow the filament.
:
:Norm
:
::Yes I did use the pt 156, thats why I thought that might be the problem....that I had the wrong type of transformer installed which blew out the filament of one of the 71a tubes. it does have a center tap on it.
::
::
:::so then the 71a blew the filament out normally as in it just failed or is there a problem elsewhere that could have caused it to go bad
:::
::::Hi Sean
::::
:::: You got it right. Item #21 is an audio interstage transformer with center tapped secondary. Sometimes it's called a driver transformer. You can use a transformer similar to A-53C or AES #P-T156. Be sure your replacement has the center tapped secondary.
::::
::::Norm
::::
:::::Hello, just thought i would add that the transformer is numbered "21" in the schematic.
:::::
::::::Hello, I am wondering if I screwed up putting a audio interstage transformer as a replacement for a pushpull transformer. I just noticed that the schematic calls the transformer right behind the two 71a tubes, a "push pull transformer" If I do need a push pull transformer then what ratings do I go by to select one?