Dead Spellman PTV50N200 - where to start?
Posted: Wed Aug 02, 2017 4:30 am
I have a Spellman PTV50N200 (see this thread for reference: viewtopic.php?f=11&t=11477) which I hadn't used much except for scaring the living daylights out of myself w/ corona effects. I made some small modifications, specifically adding a switch to the line power and re-routing the high-impedance current and voltage monitor outputs through a pair of op-amps so I could drive a meter.
I had not yet attached it to my vacuum system due to lack of an adequate feedthrough and because to ensure safety (and to fit it on my bench) I needed some careful grounding, etc arrangement -- and added a resistive ballast of around 50 Kohm. Arcs that can obliterate any normal insulation and jump six inches need special precautions.
Anyway, I got it set up, I got it making a glow discharge at a very low pressure (fractional microns I think) that my small OBIT would not do anything at, and got some X-rays I could detect w/ my geiger counter...
And then I had some unpleasant flickery instability -- rapid flashing of glow and movement of voltage/current needle --
A bit later I smelled magic smoke, and the thing reads out full current and only a small voltage. And certainly does not make a discharge anymore.
I'm not really sure where to begin -- I can't see any visibly burned stuff, and I am leery of powering the thing on when testing it due to all the voltages (of varying levels of "high") inside the case. I'm concerned my amplifiers had some kind of short -- should I start by removing them and/or changing the socketed op-amps that are electrically near them?
I had not yet attached it to my vacuum system due to lack of an adequate feedthrough and because to ensure safety (and to fit it on my bench) I needed some careful grounding, etc arrangement -- and added a resistive ballast of around 50 Kohm. Arcs that can obliterate any normal insulation and jump six inches need special precautions.
Anyway, I got it set up, I got it making a glow discharge at a very low pressure (fractional microns I think) that my small OBIT would not do anything at, and got some X-rays I could detect w/ my geiger counter...
And then I had some unpleasant flickery instability -- rapid flashing of glow and movement of voltage/current needle --
A bit later I smelled magic smoke, and the thing reads out full current and only a small voltage. And certainly does not make a discharge anymore.
I'm not really sure where to begin -- I can't see any visibly burned stuff, and I am leery of powering the thing on when testing it due to all the voltages (of varying levels of "high") inside the case. I'm concerned my amplifiers had some kind of short -- should I start by removing them and/or changing the socketed op-amps that are electrically near them?