From my research, it seemed as if the most likely problem would involve
My 39" UltraHD TV, the one that I used as my main computer monitor for almost four years, stopped working. The symptom was that it just would not turn on. The status light below the screen stayed red, meaning something like "standby". Normally it turns blue when I'm using it. Googling and watching YouTube videos convinced me that there was a chance that I could repair it. LCDs seem to have certain standard PC boards. - T-Con (timing control) - power supply - processor - LED light & video driver Replacement boards are reasonably inexpensive, apparently from chop shops (i.e. they buy broken TVs and sell the working parts). This shows someone fixing my model of TV. <https://www.youtube.com/watch?v=XD7rIEgYULI> the power supply module. I could get one for US$~20 + ~$20 for shipping. I opened up the monitor and examined the entrails. There was a burnt spot on the power supply board. I posted my problem to the BadCaps.com forum and got encouragement that a little bit of solder would fix the board. I tried this, and it worked. At least for now. I'm using the monitor to compose this mail. <https://www.badcaps.net/forum/showthread.php?p=898646> I spent several hours researching and perhaps an hour disassembling, soldering, and reassembling. It might not have been worth that time given the value of the monitor ($350 original price, but used for 4 years and obsolete). I find it satisfying to fix a hardware problem, even though I'm a software guy. Summary: not all hardware problems are hard.