Vertical Output failure on Zenith Roundie

[ctc17]

They can take one apart and rewind it? That would be a good thing as transformers for these old sets are becoming impossible to find.

I dissembled a zenith vert out transformer with a primary to secondary short and the insulation between the two winding was very poor. It was like one turn of clear tape and it had a little hole burned through it. Looked to me like they were relying to much on the wires varnish, theres a fairly high potential between those windings and there should have been more tape.

[Zenith26kc20]

They have reverse engineered a number of transformers for me. One of the strangest was the start transformer for one of my Infinity SWAMPS. They have been in business for a long time and apparently have made almost every transformer imaginable over the years.
It seems to me that Zenith put the plate connection on the inside part of the winding. This has 1200 volts signal (vertical) and 390 volts DC. When mine failed, it appears that the puncture in insultion would cause the arcing that I noticed, but no sign of distress with the 6HE5 pulled. It also makes sense with JK unhooked. I noticed a set on EBAY that the owner says gives a picture with the convergence panel unplugged. Unplugging the panel disconnects JK so that set may need a transformer too.
It the winding had the plate end outside, the only thing between windings would be 390 volts.
The engineer at TMI said the insulation may only be 3 mils thick (the nearly transparent tape). No wonder it may get into trouble....

[wa2ise]

Originally Posted by Zenith26kc20

It seems to me that Zenith put the plate connection on the inside part of the winding. This has 1200 volts signal (vertical) and 390 volts DC. When mine failed, it appears that the puncture in insulation would cause the arcing that I noticed, but no sign of distress with the 6HE5 pulled. It also makes sense with JK unhooked....
The engineer at TMI said the insulation may only be 3 mils thick (the nearly transparent tape). No wonder it may get into trouble....

Maybe one should mount the transformer with its frame and core insulated from the chassis ground. Thus making life on the insulation a little easier. Though the transformer frame would become a shock hazard, but once the TV is back together that shouldn't be a big issue.

[compucat]

This is really interesting. I have a 25MC33 Zenith Roundie and I have had this happen twice with the vertical output transformer. I would definitely like to find a permanent fix. If better replacements could be made, I would be interested in buying one. This does seem to be the only real weakness in the Zenith roundie design. Lets us know what happens with the transformer.