At 20.33 11/11/2007, you wrote:
The strip that carries the high voltage to the CRT in my HP 141T has
delaminated, and is arcing to the adjacent CRT shield. On a web page,
WB8ZDF mentions using super glue to repair the strip, but it seems
like I would have only one shot at the repair, and I don't trust a
random glue formulation to hold up to high voltage. Does anyone have
a better suggestion? The CRT seems to be in good shape otherwise.
Looking at a bad CRT, I see the strip is soldered to the CRT near the
face plate. I suppose I could try transferring the strip from the bad
CRT, but that looks like it would be tricky to do without damaging
something.
Thanks,
Jack Rouse
Jack,
I did it several times in the past. Only one wire (the one most separated from the others) carries about 6kV and must be replaced; remaining wires have voltages in the hundreds of V.
I remove all the insulation on the CRT and clean the area with isopropilic alcohol, to remove glue residuals. The HV wire on the strip is removed, then I solder a single wire to the HV pin on the CRT, and route that wire to the thick red wire that comes to the strip connector. I use a thin wire with PTFE insulation, ex avionic surplus. It runs practically in air, so no danger of discharge. Then I replace the original brown insulation, and cover with black PVC tape.
I always try to be fast while soldering, and to apply a minimum heath to the pin, not to break the metal-glass junction. The ideal would be to use low-temp solder, but I don't have it.
I repaired half a dozen of CRTs in that way, and all worked well (and still work after years).
The new wire must be quite thin, since there is no much space between the CRT face plate and the front panel. If the repaired CRT becomes too large it will not re-enter in the box.
73 - Marco IK1ODO / AI4YF
