Testing single ended output transformer

[leydenjar]

I know how to test a push-pull OT. When I test a push pull OT I run a small ac voltage into the secondary and test each 1/2 of the primary. They should be the same.


But how do you test a single ended OT with no center tap? When they go bad does the primary open or...? Do they go bad?

[52 Bill]

I know how to test a push-pull OT. When I test a push pull OT I run a small ac voltage into the secondary and test each 1/2 of the primary. They should be the same.

But how do you test a single ended OT with no center tap? When they go bad does the primary open or...? Do they go bad?

Any transformer can go bad. They can all go bad in lots of ways, it doesn't matter whether it's a single ended transformer or a push pull or a multi tap power transformer. They can go open, they can short primary to secondary, they can short winding to frame, they can have shorted turns, etc.

In your example of testing a push pull output transformer, you apply a small voltage to the secondary and read the voltage on the two halves of the primary. What do you look for? Do both sides have to match in voltage? Are you looking for a specific voltage ratio secondary to primary?

[leydenjar]

In your example of testing a push pull output transformer, you apply a small voltage to the secondary and read the voltage on the two halves of the primary. What do you look for? Do both sides have to match in voltage? Are you looking for a specific voltage ratio secondary to primary?

I make sure the voltage on the OT primary on each half is the same.

[52 Bill]

I make sure the voltage on the OT primary on each half is the same.

OK, then do you calculate the impedance ratio from the voltages that you get?

If you do, then do the same thing with the single ended transformer. As long as it comes up to the correct ratio for the tube and speaker combination that you are using, then it's probably ok.

I would add a resistance test to be sure that there is no continuity from either winding to the core.

[leydenjar]

Thanks 52 Bill!