Hisense 40H4F no backlight but turns off after splash screen

[frannyjunk]

So I have this Hisense tv where the backlight does not come on. But when it is turned on, when I shine a flashlight on the screen, I can clearly see the splash screen then it turns off. I looked at the mainboard and was expecting to see bulged capacitors, but they all look fine. I unplugged the backlight from the mainboard, and get the same symptoms (i.e. no backlight, dark splash screen then just a black screen). Is this just a backlight issues? Do Hisense tvs turn off by itself if the backlights are unplugged or are bad? Or is this a mainboard issue?

TIA.

[frannyjunk]

[Diah]

no risk its just 40 size.... take the screen apart you will see the led defect

[lotas]

Basically, when the backlight doesn't work, Hisense triggers a protection switch and the power supply cuts off the secondary voltage.

[Diah]

Basically, when the backlight doesn't work, Hisense triggers a protection switch and the power supply cuts off the secondary voltage.

this is early version from Hisense.. 1080 pixels not 4K or later no protection , and the LED they used as direct LED or Edge one was with zener protection , which they are now with old of production dead already.

[frannyjunk]

After some research, I located the reset button so I reset the tv. Now the backlight is still off, but the tv boot loops. Part of the protection circuitry? I have ordered the backlights from Aliexpress but they won't arrive for another 2 weeks. In the meantime, I am wondering if I should also buy a main board. Seems like a lot to spend on a 40" tv. Any guesses if the main board is ok?

[lotas]

I'm not familiar with this chassis and can't comment on this reboot, but it could be due to a faulty backlight. Try disabling the Wi-Fi module, then disconnecting the LVDS cable. If that doesn't help, try connecting to the UART and checking the boot log to see where it's failing. There might be an eMMC issue.

[frannyjunk]

I'm not familiar with this chassis and can't comment on this reboot, but it could be due to a faulty backlight. Try disabling the Wi-Fi module, then disconnecting the LVDS cable. If that doesn't help, try connecting to the UART and checking the boot log to see where it's failing. There might be an eMMC issue.

Thanks! At this point, I will wait for the backlights to arrive then will replace them on the tv. Should the tv still bootloop, my next couse of action is to update the firmware using a USB drive. If that fails, then replace the main board. I hope the eMMC is on the main board and not on the lcd panel board.

[lotas]

I hope the eMMC is on the main board and not on the lcd panel board.

Yes, the eMMC is located on the motherboard, most likely under the heatsink on the processor.