Capehart 661-P

[ohohyodafarted]

Originally Posted by Phil Nelson

I know I have read about someone (Eric H?) who at least thought of filing or grinding out enough glass to expose a broken lead. Whether he actually tried it, much less succeeded, I don't recall offhand.

Wish I was better friends with my dentist. Bet she could do it in no time, and she's got the gear: water-cooled instruments, super magnifying goggles, etc.

Phil Nelson

Phill, I have done the glass grinding successfully. I did it on 3 leads of a 21axp22 that I was trying to salvage. The opperation was a success but the patient died (the crt was very weak) I eventyally took the crt to Scotty for rebuild and it incured catastrophic failure of the face plate in his oven along with another tube, but that is a whole nother story.

What you need for the grinding on the crt button is diamond impregnated burrs to put in your Dremel. The diamond burrs will grind glass very easily. I purchased an entire kit assortment on ebay and they were not at all expensive. Standard carbide burrs will NOT do the job. Don't even attempt with anything less than diamond.

After you expose some of the wire it will be difficult to get solder to stick. I took a small patch, of Chemtronics solder wick and placed it over the wire stub and saturated the patch with solder. Then I tack soldered a fine wire lead to the solder patch that was stuck to the wire stub.

You only need to expose the tip of the wire, perhaps .010" I would not risk going much farther. You will not be able to attach a wire directly to the stub because the glass will sink the heat from the wire and you cant risk heating the glass much because you could crack the glass if it gets too hot.

John Folsom has also accomplished wire attachment using a silver epoxy compound. Because you are attaching to a grid wire, there is very little current flow and the silver epoxy is conductive enough to work in this situation. Being as your issue is a grid wire, this epoxy method may be your best bet.

Good Luck!