I am scratching my head over an old Tek 2445.
It might work for hours without problems, then it might do a few HV discharges in the A9 high-voltage assembly and then it continue to work. Or it doesn't and just continues with a rapid series of these discharges. With every discharge the CRT goes dark for a moment. This of course I understand.
It is A9 making the trouble, because I removed the cabinet and I can hear static building up and then I can see a flash somewhere on the HV side under the A9 board shield when the discharge happens. And I hear the discharge. I can't see exactly where the flash happens, because of the board shield. However, when removing the board shield I can still hear static building up, but no discharge happens any more. So I have no clue where the problem is.
After removing the A9 board I did a thorough (at least I think so) visual inspection for burn marks, broken insulation of the anode cable, burned traces on both PCB sides, cracks in the HV multiplier's case or any of the other compontens on the HV side of the multiplier. Noting. Everything looks fine.
I checked the board shield and the chassis for marks, too. Nothing. I checked the resistors on the HV side of the PCB. All have their nominal values. I checked the capacitors for shorts. Non. I have no clue what is going on.
Before I start to gamble and hunt for a replacement multiplier or a complete A9 board, is there anything else I could check? Any other ideas?
Hunter