So just as I need it for a teardown vid, my Faxitron has started playing up...
From power-on it will sometimes take one or two decent exposures, then the x-ray power falls off rapidly.
The beam current, measured from the test sockets, falls off substantially, from its nominal 300mv, down to about 20 or 30mV over a few mins - not very consistent but seems to be getting worse.
Other voltages seem OK - EHT measured from test sockets is rock solid, as are filament & focus voltages.
One thing that does change significantly between standby and run modes is the grid voltage - this sits at its nominal -140v in standby , then rises to 4-600v when the beam is on. The manual doesn't say much about the conditions under which the voltages are measured though and there isn't any more info, though the way the HV modules are wired suggests this is normal.
Disconnecting this & measuring the PCB side makes little difference, so it isn't something coming back from the tube.
Does anyone have a working MX20 they could measure some voltages on for me ?
I'd be really grateful if somone could measure supply inputs to the HV modules, as these determine the HV outputs of the modules. Points shown in orange on attached pic. Can be measured relative to chassis, in both standby and run mode at a known kv setting.
Fortunately these are accessible from the top without removing the PCB.