LG 32LN578V - Picture; No Backlight

[speedypro]

While searching this forum, I have not seen anything close to what I have; picture but no backlight.

PCB: EAX64905001 (2.7) Rev 3.0





Before concluding that it's a faulty panel, as I get no voltage going to the backlight, how to test the pcb for faults as in...where to test?

[dick_barton]

Re: LG 32LN578V - Picture; No Backlight

What voltages do you have on P201. What voltage across the two legs of C109.
There are several 0 ohm resistors around the led driver IC . Do they check out OK. What is the led driver chip part number. Has Q801 checked out OK.

[dskall]

Re: LG 32LN578V - Picture; No Backlight

472 posts. You should know the drill by now
Need voltages from connector that goes from power supply board to main board. Will need pin#-pin label-Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Label - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.

[ReeceyBurger123]

Re: LG 32LN578V - Picture; No Backlight

472 posts. You should know the drill by now
need voltages from connector that goes from power supply board to main board. Will need pin#-pin label-pin voltage in standby-pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - pin label - pin voltage standby - pin voltage power on
1 - xxxxxxx - xxv - xxxv
2 - xxxxxxx - xxxv - xxxv
3 - xxxxxxx - xxxv - xxxv
4 - etc.

i cant bloody agree more does my head in !!!

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

Sorry for late reply. Previously I've replaced the led driver: MAP3202 but same issue. Since I had all the time in the world, I replace the faulty smd led and now all is well: backlight strips work.

Powering on the tv I got the lg logo (backlight works). After that, nothing; just pitch black....the backlight is still on (i can see the light from the back side of the panel). I feel this tv had more than one issues. Press the other buttons on the control pad shows nothing on screen. Power off and on, I get the lg logo as if the tv is in good health.

[dick_barton]

Re: LG 32LN578V - Picture; No Backlight

Do you have sound. You can input via the SCART.

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

Do you have sound. You can input via the SCART.

No sound with Scart. Not sure if the tv was last used on hdmi. I also noticed that a hdmi socket was removed from the main board, although it looks professionally done.

[dick_barton]

Re: LG 32LN578V - Picture; No Backlight

Switch the item connected to the scart off and on several times and if the mainboard is working it normally switches to it.

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

Switch the item connected to the scart off and on several times and if the mainboard is working it normally switches to it.

Even though I do not see the volume up/down image on tv when buttons are pressed?

[dick_barton]

Re: LG 32LN578V - Picture; No Backlight

If you connect a DVD player with disc which I do, you can normally hear it or use the remote / side button controls to raise the volume. Normally I can hear the sound that it is playing.

The set I repaired yesterday, once I got the power supply up and running I still had no backlight so played a dvd through it to check that I did not have a problem with the mainboard. That worked so continued fault finding on the backlights which was the only problem with the set.

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

If you connect a DVD player with disc which I do, you can normally hear it or use the remote / side button controls to raise the volume. Normally I can hear the sound that it is playing.

I feel it's the board. Im using a laptop. When I connect the tv, the laptop sound mutes as if it transferred to the tv but no sound nor display. Unplug the hdmi cable, sound returns to the laptop. Also, only one hdmi port enables this behaviour

[vinceroger69]

Re: LG 32LN578V - Picture; No Backlight

what mainboard is used in this set

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

what mainboard is used in this set

eax64797004 1.1

[dskall]

Re: LG 32LN578V - Picture; No Backlight

No sound with Scart. Not sure if the tv was last used on hdmi. I also noticed that a hdmi socket was removed from the main board, although it looks professionally done.

Sounds like someone threw in defective old mainboard they used for parts

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

Could I replace this with a 42" model board? I cant find any 32" board.

[dick_barton]

Re: LG 32LN578V - Picture; No Backlight

Available from

https://spares2repair.co.uk/lg-32ln5...ax64797004-1.1

I've used them and they are fine.

[speedypro]

Re: LG 32LN578V - Picture; No Backlight

Sounds like someone threw in defective old mainboard they used for parts

Correct. New board, all is well.

[amirabueno]

Re: LG 32LN578V - Picture; No Backlight

anybody can help where can we buy SSC1S311 for this board

[vinceroger69]

Re: LG 32LN578V - Picture; No Backlight

anybody can help where can we buy SSC1S311 for this board

https://www.aliexpress.com/item/Free...7e3f6eb3ebb7-1

[ronhayes]

Re: LG 32LN578V - Picture; No Backlight

Hi all
Sorry to butt in on this one
But does anyone have a service manual for this set ?
I have just had one of these in with the same issue no backlights.
I pulled p801 and applied 60v using a variable p/s going from 0v to 60v very slowly directly to backlights still no backlights.
I then disassembled the screen to gain access to the led backlights there are three strips of 7 backlights I then applied 20v to each strip using variable p/s and found one led on two of the strips had blown I replaced them then applied 60v slowly to all three strips again and all worked fine. I then reassembled the screen and powered up the TV with all connected but still no backlights! I then pulled p801 and applied 60v to backlights while TV was powered up I have a perfect picture and sound.
So I could now do with a service manual covering the p/s or does anyone know what causes this issue on this model. ?
Much appreciate any help.