This old 15" monitor detected VGA signal and powered on accordingly, but there was no backlight and no image was formed on LCD. I thought that it was a typical inverter problem, but the absence of image on LCD misleaded me at first.
No bulging caps and ESR OK. I get schematics. There's 16V for inverter, 3.3V too, but not the 5V for panel. Then I discover that PF751 is actually a fuse! It really looks like a ferrite / coil! But after unsoldering I can read "bel MS 2A" underneath. It's a 2A / 125V fuse and it's open.
DC-DC IC781 MC34063ACN seems fine. I just detect broken solder joints on 2 inverter transistors (Q759, Q760, 2SC5706), due to repeated heating-cooling cycles over years. Ressolder all 4 transistors on inverter, replace fuse with a 2A / 230V one and it works again.
No bulging caps and ESR OK. I get schematics. There's 16V for inverter, 3.3V too, but not the 5V for panel. Then I discover that PF751 is actually a fuse! It really looks like a ferrite / coil! But after unsoldering I can read "bel MS 2A" underneath. It's a 2A / 125V fuse and it's open.
DC-DC IC781 MC34063ACN seems fine. I just detect broken solder joints on 2 inverter transistors (Q759, Q760, 2SC5706), due to repeated heating-cooling cycles over years. Ressolder all 4 transistors on inverter, replace fuse with a 2A / 230V one and it works again.