LG 42LD560 No Picture No Backlight No Sound Pulsing LED

[theduke-returns]

Hi All

I was watching my TV when I heard a crackling and slight hiss and the picture pixelated and the everything turned off except the LED. Hoping to get some help to diagnose what could be the matter. Below are more details and also info about what I have checked so far.

Plugged in turned on via button on side the led just pulses on and off I guess you could call it a slow flash


Model
LG 42LD560 - TA .AAUWLJD

PSU PCB
EAX61124201/15 Rev 1.2
Barcode sticker number
TA9AE608694023536 (1.2)

Main PCB
EAX61768307(0)
BCM High
LB03B/LJ03B/LL03B/LT03B

What I have checked.

Electro Capacitors on PSU seem to be fine no puffiness. Also seem to charge up when meter is used only to 3v though. No real visual clues to what let its magic smoke out.

Main PCB connector voltages
measured 12v yes
measured 3.5v yes (3.4v ish measured)
measured 20v no (nothing present will double check later)

didn't measure (will update)
error
P-DIM
A-DIM
INV ON/OFF
POWER ON

Any help would be greatly appreciated.

Cheers

Christian

[budm]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Post good clear pictures of the back side of the TV so we can see all the boards and how they are connected together, then the pictures of each board, that will be a start.

[theduke-returns]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Hi budm

Thanks for the quick reply.Sorry for the delay. Here are the pictures requested hopefully they are clear enough. I only have a phone camera. Also have an update on measured voltages on the cable between the two boards (main and psu)

label (measured)

NC Error (0.68v)
12v (12.2v) P dim (2.6v)
12v (12.2v) A dim (0.055v) I assume zero
12v (12.2v) Inv on/off (0.031v) I assume zero
gnd gnd
gnd gnd
3.5v (3.38v) 3.5v (3.38v)
gnd gnd
gnd gnd
20v (20.6v) 20v (20.6v)
p on (3.2v) 20v (20.6v)

I also removed and tested the fets that switch the back light tubes but they are fine, hope that's helpful

Back of TV
http://s1.postimg.org/jlltnbmzj/Back1.jpg
http://s1.postimg.org/ns6o2nmlb/Back2.jpg

PSU
http://s1.postimg.org/qasd3c8bj/PSU_Top.jpg
http://s1.postimg.org/5k9u1rjfj/PSU_Bottom.jpg

Main
http://s1.postimg.org/w42f3wjz3/Main_Top.jpg
http://s1.postimg.org/r7ysc7jtr/Main_Bottom.jpg


Cheers

Christian

[budm]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

"Inv on/off (0.031v) I assume zero" The main board is not sending the INV ON/OFF (same as BL_ON: Backlights ON), on = >2VDC, OFF = <1VDC.

[aarty]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Hi peoples.

Was the tv repaired as I have the same issue.

[budm]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

@aarty, the OP never come back so you should start by providing good clear pictures.
https://www.badcaps.net/forum/showthread.php?t=1868
https://www.badcaps.net/forum/showthread.php?t=39740

[saddle_au]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Have posted thoughts on this model on the following thread.

https://www.badcaps.net/forum/showth...hlight=42LD560

[edilsss]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Hey guys,can you please help me identify IC201 part number/type,mine was pulled down from the board...it is located on the bottom of the smps board.

[vlolham]

Re: LG 42LD560 No Picture No Backlight No Sound Pulsing LED

Hi,

Did you managed to diagnose the fault yet?
I have the same problem and I have gone as far as, see below:

I examine the voltage output 12V, 20V on standby when the red LED flashes the voltage is at max, but when turn on, both voltages drop to zero.
Those voltages are coming out of T501.
There are two Opto couples IC502 and IC503 managing the voltage protection feedback, in case of any abnormality they will shutdown the oscillator and transformer will stop working.
I'll check that weather is any short or leak on 12V or 20V coming from the interface board, because I have two power boards and both show the same problem, so I assume looking for the fault on the interface board.
will get back with more.

VL.