So Before I Replace This Expensive Output Transformer...

[schmidlin]

I thought I would run it past some fresh eyes. The darn thing tests perfectly: the turns ratio is spot on, no continuity between primary and secondary. BUT I am getting 1 ohm to ground (on the iron itself) from the CT primary. Opened it up and nothing looks amiss. Lost cause? TIA.

 

[Jeff Gehring]

About the only last chance I'd give it, is to pull the bell covers, which it sounds like you have done. Other than that, it's probably trash...

 

[trobbins]

So you see each primary half-winding DCR when measuring from each anode end of winding to core?

Can you see the CT wires going in to the winding stack? That would normally be about mid-way between inner and outer layers, unless you have some interleaving. Normally the winding is insulated from the core with solid cardboard sleeves on the winding edges that are in proximity to the core.

 

[skeeterbuck]

Check this out:

http://www.geofex.com/ampdbug/outtrans.htm

 

[schmidlin]

Thanks, gang. I'm calling it dead. Sure pops a fuse fast.

 

[J M Fahey]

Have you tested the transformer with all wires disconnected, unmounted and away from the chassis, and sitting on some insulator as, say, a piece of wood or a rubber mat?
In such case, what do you measure from each HV tap (plate 1/plate2/CT) to laminations and/or covers?

What amp/transformer is it?

 

[mark norwine]

If there's *any* continuity between *any* lead & the metal of the laminations, then it has an internal breakdown & it's dead.

 

[trobbins]

If there's *any* continuity between *any* lead & the metal of the laminations, then it has an internal breakdown & it's dead.

True - but then for some of us the interest turns to physically where the fault occurred, and then to why the fault occurred.