Good day,
I have this Hisense 39N2171 that came in for a no power repair. I tried recapping it, but the 12V rail would always give out whenever the TV tries to boot. My best guess is that there is a failing component that somehow knocked the feedback loop right over the edge, but since I don't want to spend any more time on this part, I decided to replace the power supply section with a 12V PSU + backlight driver module. I also replaced all the backlight LEDs as when I tried to test the backlight driver, the backlight was not coming on at all. Now the TV boots and pretty much works except for the backlight dimming, which I know how to fix and this:
https://youtu.be/LKCqJMBaM8M
This dark bar starts at around 1cm from the top and grows bigger downward as the TV is on for longer. At some point it will cover the top half of the screen and the bottom half will flicker. This bar is less obvious when the image is plain white. I speculate that the fault is on the tcon board along the bottom of the screen. It's likely temperature dependent, as the "progress" it has made still persists after immediately restarting the screen. It would start over only after letting the TV off for a while.
I could not find anything online that's specifically related to this behavior. What I could do next is to measure the bias rails to see if anything is weird, or to reflow the solder on the tcon, but honestly I don't think these would help. As of now, I'm pretty stumped on this repair... So I would like to ask for some help on how to proceed with this. I've attached images of the main board, and what the dark pixels look like. I can upload more photos if it's needed. Thank you
I have this Hisense 39N2171 that came in for a no power repair. I tried recapping it, but the 12V rail would always give out whenever the TV tries to boot. My best guess is that there is a failing component that somehow knocked the feedback loop right over the edge, but since I don't want to spend any more time on this part, I decided to replace the power supply section with a 12V PSU + backlight driver module. I also replaced all the backlight LEDs as when I tried to test the backlight driver, the backlight was not coming on at all. Now the TV boots and pretty much works except for the backlight dimming, which I know how to fix and this:
https://youtu.be/LKCqJMBaM8M
This dark bar starts at around 1cm from the top and grows bigger downward as the TV is on for longer. At some point it will cover the top half of the screen and the bottom half will flicker. This bar is less obvious when the image is plain white. I speculate that the fault is on the tcon board along the bottom of the screen. It's likely temperature dependent, as the "progress" it has made still persists after immediately restarting the screen. It would start over only after letting the TV off for a while.
I could not find anything online that's specifically related to this behavior. What I could do next is to measure the bias rails to see if anything is weird, or to reflow the solder on the tcon, but honestly I don't think these would help. As of now, I'm pretty stumped on this repair... So I would like to ask for some help on how to proceed with this. I've attached images of the main board, and what the dark pixels look like. I can upload more photos if it's needed. Thank you
Attached Files
