Black Screen with Audio
I’m working on troubleshooting a 65” Sony tv model xbr-65x850f that was manufactured in 2018. The tv turns on/off but does not display any images (flashlight test) and I cannot see any backlight. There is audio. What is interesting is that when I perform a complete factory reset, I can see traces of picture with a flashlight, but when I turn off the TV and turn it back on, it’s gone. So far, I’ve checked the power supply unit output to the main board and t-con and the voltage readings are correct. I tried measuring the +out and -out voltages that I assume feed to the LED lights but I’m not too sure if what I’ve measured is correct. For all the +out pins, I was reading around 71V with the power on. I was getting 0v for the -out pins. The power supply board has text that says LED==117.4V. Could that be the issue? The power supply board model is AP-P288AM.
I’m also trying to measure voltages on the t-con board but cannot find any test pads. Can I get some insight on how to measure the voltage for VCC, VDD, VGL, VGH, etc? The t-con board model is 6870c-0749a.