Re: Wbox 55UD-H8076-0490(K550wdc2) - Backlight Driver

The leds blink on for too short of time for the meter to register any voltage. there are only 2 strings of leds as well

Re: Wbox 55UD-H8076-0490(K550wdc2) - Backlight Driver

Isnt actually anything soldered to those pads. I looked at all the solder joints under a microscope so i dont "think" its a bad joint. Wish it was tho!

On one of the boards i shorted the opto coupler when i was probing and the leds do turn on. There is high voltage on the high side of the transformer but seems like the feedback circuit is shutting it down.

Re: Wbox 55UD-H8076-0490(K550wdc2) - Backlight Driver

BL adj - 2.7
BL ON - 1.4
12v - 12.2
5v - 5
5vsb - 5
PWR on off- 3.6

When jumpered to pwr the board powers on. then jumper to BL On/Off they do not even blink. when powering on with the power button they blink on.

That is just part of the transformer and glue on it.

Hi all, looking for some help diagnosing the powersupply / LED driver on some tvs. I have 5 of them all with the same issue that are out of warranty and would like to fix for my customers.

Then powering on the TV the backlight will blink on then turn off untill the next power cycle. The LED driver output will go to proper voltage(200Vdc) for less than 1sec then drop to under than 10v. Will do the same thing is leds are disconnected.

BL_ON has 1.5ish volts

LED Strips all turn on with a tester. one of the tvs does have a dead strip.

Seems...

Re: New Members - please post your introductions here

yet another newbie;

I own my own company installing Security systems and cameras. I also do IT work for various small and medium business. Have the odd person asking me to repair their tv. I haven't needed to ask for help yet but figured i should be ready for when i do!

Thanks