CRT monitor power issue
 

I saved 4 monitors from the bins a while back, this one (proview ije558) worked for a couple of months before failing, started with what I can only describe as a boot loop, before dying completely.
I've spent some time working on it and have managed to get power back on after replacing a faulty cap and MOSFET.
When no image is displayed, it powers on as expected, static in the tube, degauss etc, but when an image is displayed, it goes back to the "boot loop" where it clicks on and off rapidly.
I'm assuming this is still a power delivery issue, but I'm not sure where to check from here.
If anyone has advise I would be grateful.

Various possibilities exists; some cross on my mind:
- failing pulse capacitor (the caps connected to collector of HOT to ground or to the modulation diode***), increasing HV and triggering HV protection;
- failing flyback draining too much current;
- buck supply for the flyback, for models employing this: losing regulation, bad cap or shorted MOSFET;
- PSU with failed regulation, throwing too much secondary voltages at power on;
***the one stacked below to damper diode, for H size/wide/scan line geometry control).

Awesome, thanks for the advice.

Alex covered it. You can check the main voltage B+ voltage,
should be +- 130 V to CHASSIS ground. Almost always a marked
test point. That can cut down on possibilities.
If the FET was shorted check that area carefully too.

good luck
Zeno:smoke:
LFOD !