2021-11-11 Chimei LCD monitor Delta power supply fixed
tl;dr: It was the CapXon electrolytic capacitors! All the CapXon capacitors!
I dabble as a hobbyist in electronics, but I still feel proud when I manage to repair some piece of gear with a soldering iron in my hands. This time the backlight on my aging Chimei CMV 221D LCD monitor from March 2007 refused to come on. It had been playing up for a while, only coming on about 25% of the time I turned the monitor on, so I'd gotten into the habit of leaving it on all the time, and disabling the sleep mode. Unfortunately, I had to turn it off for a night, and after that, it refused to come on. So, I pulled it apart and uncovered the power supply, and immediately located a problem. Six problems, in fact. Three are pretty obvious in the photo, with visible leaks, especially the large main input 120µF 400v filter cap, and the two towards the centre-right (220µF 25v and 1000µF 25v). Two more show noticeable bulges (both 220µF 25v), and the remaining one, the 1000µF 25v one lying down towards the top-right also has a bulge not visible in the photo.
All the black CapXon caps, and only the CapXon caps, were either bulging or leaking. 20 minutes later after a quick walk to Jaycar, I had replacement caps. De-soldered the CapXon caps, soldered in the replacements, and bingo, one working monitor, which I'm using right now to create this page!
