Quote:
Originally Posted by MotorBikeLes
I have never come across this myself, but I believe it is a well known problem with similar TEK HV transformers. Sometimes they are charred I believe. You could try drilling a series of stepped holes around the connection pin / pins thereby increasing the insulated path, and reducing likelihood of further leakage. Alternatively, unsolder the wires, cut off much of the paxolin, and add another layer above it fixed to the rest of the original with some epoxy resin.
Les.
|
Sorry for the late answer. I didn't notice your reply until now, because the email notification did not work.
I found that the pins can be removed by carefully using a pair of pliers after completely removing all solder with solder wick. The 1.5mm diameter pins are made of bent metal sheet with a bump on the reverse side of the board. This way, they get fixed to the paxolin board as soon as the transformer wires are soldered to the other side. At the moment, I see two repair options. Option one would be to replace the board with a new paxolin (often called Pertinax here in Germany) or FR4 board. The board thickness is 3.5mm and I could get some pre-cut 4mm Pertinax or FR4 for less than 20€. This would have the disadvantage, that I would have to remove all solder posts, even the ones with the flimsy wires at the low voltage side.
The other option would make use of some sleeves, consisting most likely of silicone carbide, that I found on some power MOSFET legs in my magic part box (see attached image). They have an inner diameter of 1.5mm, an outer diameter of 3.5mm and the perfect height for the job. I could widen the original holes on the HV-side of the transformer to 3.5mm, insert and glue in the carbide sleeves and insert the transformer solder posts into the sleeves.
However, both solutions would require tools for precision drilling perpendicular holes into the boards and I do not own a drill stand, just a Dremel-like handheld multi-tool. In addition to that, both solutions would require a HV-insulating and heat resistant lacquer, to cover the posts. I think, part of the observed arcing at the solder post was due to a damaged lacquer coating. The two-component epoxy glue I have would most likely melt during soldering the wires back on. So I tried to determine what the original lacquer on the board is. At first, I suspected it to be shellac, but putting a flake of it in methylated spirits did not dissolve it, even after a week. So it is probably made of something else.
Does anyone have a hint what HV-insulating epoxy could be used here?