Toshiba 50L1350uc no back light

[nickmatine1]

this unit has for one second a short flash and after that no picture and has sound

the voltage is this WITH or WIHOUT connector plugged

start as 130 v for both l1 and l2 for one second and after is

L2+ 77DC

L1+ 77VDC
measured on chassis ground


and i repeat with coonector plugged or unplugged (for led)
any ideas
thanks

[nickmatine1]

Re: Toshiba 50L1350uc no back light

some pictures

[dick_barton]

Re: Toshiba 50L1350uc no back light

Is BL_ON/OFF => 2.5V. If it is then it looks initially like an led string problem.
What's the LCD panel number

[nickmatine1]

Re: Toshiba 50L1350uc no back light

yes bl-on/off is 3.3 v

and when the tv open for second
L2 is 90v and drop to 76
L1 is 138v and drop to 76


lcd panel is LC500DUE
SF R1
LG display

thanks

[dskall]

Re: Toshiba 50L1350uc no back light

Led problem

[nickmatine1]

Re: Toshiba 50L1350uc no back light

ok. i'll try to open it and let you guys know
thanks for your help

[nickmatine1]

Re: Toshiba 50L1350uc no back light

before start to remove LED
i put another LED panel from a cracked LG 49LF5900 (this one work good just cracked screen LED panel is china HC490EUN-SLES2-2132) and has the same connector. but still have backlight for one second. tested also with flashlight and has image but still not backlight

[dskall]

Re: Toshiba 50L1350uc no back light

Different panel different current draw. Each board is set to work with a certain panel

[dick_barton]

Re: Toshiba 50L1350uc no back light

led problem

The panel is set up with 3 strips of leds each having 10 leds per strip. Running typical voltage of 111V
There are 2 of these as show in the attachment.

Can you double check L1 & L2 again with the led connector disconnected and see if they initially peak at the same voltage.
If they do then I would suspect a led fault along L2 strips.

Edit
Just re-read the thread. Are L1 & L2 both at 130V at switch on as you say in post #1 or now at the different voltages you say in post #4???