I have a dead Electrohome monitor on a cnc machine.The model is a
38-K421MD-04. If I hook a voltmeter on to check the grid voltage and power up the monitor works fine.If I power up with the meter disconnected it doesn`t work. Does anyone have any ideas?Does anyone have a schematic? regards,Mark.Sounds like the internal resistance of your VOM is providing a path to ground enough to activate the secondary HV section of the Flyback xfmr. My diagnosis is a defective flyback xfmr, or a bad solder on the ground for the FBT secondary.
You need to check the grid circuit then. Obviously it's not right, and it may be shutting down or something. Depending on the repair, how quick do they need it, how bad do they need it quick, you might get by with a 1 meg resistor from that grid to ground. Acually I'd be looking for an open high value resistor from the grid to ground, since this is what you are supplying with your meter.
JURB
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