[Pete Deksnis]

The last of my three vertical convergence transformers failed. One is used in a CTC2, the CT-100 chassis. Sunday morning June 18, 2006, the fuse protecting the H-V cage blew on turn-on. Unlike my two other failed transformers, however, which still display correct dc resistance, this failure wiped out the secondary. The tap is completely open. There are about 12 Meg between the top and bottom of the secondary where about 12 k-ohms should be. This part has an extremely high failure rate. Probably second only to the 'white' peaking coils that rot open.

For the repair, I tacked in one of John Folsom’s newly manufactured replacements I've had for about a year now. It was static-tested at about 4 kV across primary-to-secondary for a few hours when it arrived last June, and so I expected a no-issue installation.

On the bench, the H-V ran a steady 21 kV with the new transformer in place and the H-V control set wide open with a 115-Vac line. The focus voltage, which passes through the secondary and is the reason for all the stress on the transformer, is steady at 3.5 to 4 kV, depending on the focus control position.

Picture is of the new transformer on the rear of the H-V cage.

In the future, I’ll remove the failed core from the transformer housing and use the original case around the new transformer.

Returned the chassis to the cabinet today, cranked the H-V control back to the specified 19.5 kV and while I haven’t reconverged it yet, it's perfectly watchable.