LG 37lv375s no 24V

[chrle]

hello guys

I buy today LG 37lv375s Smart tv

Problem is when I plug cord and turn on tv ,something clicks ,flash 2 times red light and off.

backlight not turning on

I measure voltage on power board

I got 3.5 volt,12volt but 24volt is 0.voltmeter shows 8 volt for second and then 0 ,jumping voltage.

[budm]

Re: LG 37lv375s no 24V

Can we get straight shot pictures of the whole top side and bottom side of this power supply board?

[R_J]

Re: LG 37lv375s no 24V

If you have +12 volts, you should also have +24 volts, they both come from the same T101 transformer, so check for poor connections on the transformer pins and diodes 251, D252, D255

[chrle]

Re: LG 37lv375s no 24V

uploading pic

[chrle]

Re: LG 37lv375s no 24V

ok guys I have all voltages OK on power board

3,5 12v and 24v

now I must to see why is not powering backlight..

[chrle]

Re: LG 37lv375s no 24V

.

[nomoresonys]

Re: LG 37lv375s no 24V

Try tv unplugged from outlet, unplug cable from powerboard to mainboard, plug tv back in outlet, see if backlight comes on and stays on.

[nomoresonys]

Re: LG 37lv375s no 24V

After above test, with cable hooked back up, test connector from mainboard to powerboard on powerboard side, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description and condition on and off.

[chrle]

Re: LG 37lv375s no 24V

Try tv unplugged from outlet, unplug cable from powerboard to mainboard, plug tv back in outlet, see if backlight comes on and stays on.

ok cable unpluged from main board

power tv ,no backlight

[chrle]

Re: LG 37lv375s no 24V

After above test, with cable hooked back up, test connector from mainboard to powerboard on powerboard side, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description and condition on and off.

ok tv in stand by mode

N.C
0v
0v
0v
GND
GND
3.5V
3.5V
GND
GND
0v
power-on 0V

after turn on :

N.C
12.1V
12.1V
12.1V
GND
GND
3.5V
3.5V
GND
GND
24.9V
POWER -On 3.3V

[nomoresonys]

Re: LG 37lv375s no 24V

If you have an ok button on the tv panel try holding that for 15 seconds see if tv starts up or try holding ok button on panel and remote for 15 seconds or so.

[nomoresonys]

Re: LG 37lv375s no 24V

Guessing a backlight issue, which it usually is like 98 percent of the cases with led lit tvs.

[chrle]

Re: LG 37lv375s no 24V

Guessing a backlight issue, which it usually is like 98 percent of the cases with led lit tvs.

ok but I cant see menu when I put light on display

and i look on power led turn to blue when I turn on tv..hmm

[chrle]

Re: LG 37lv375s no 24V

I think that Led driver board is faulty,24 volt is coming to board but 0V out from board, with or without cable disconnected from led strips

[R_J]

Re: LG 37lv375s no 24V

Check the fuse on the driver board, it is labeled F101 [M] (4amp), if the fuse is ok, check the voltage across c219 or c220, this voltage needs to be monitored when you first turn on the tv, If there is a fault with the backlights, the board will error and shut down.

[chrle]

Re: LG 37lv375s no 24V

Check the fuse on the driver board, it is labeled F101 [M] (4amp), if the fuse is ok, check the voltage across c219 or c220, this voltage needs to be monitored when you first turn on the tv, If there is a fault with the backlights, the board will error and shut down.

fuse is ok ,no voltage on c219 and c220

C101 24v

[R_J]

Re: LG 37lv375s no 24V

It could be that there is no backlight on or INV_ON signal going to that driver board, My guess is that Q502 switches the +24 volts on for the driver board, It looks like the BLON is pin 12 of J1, check the voltage on pins 11~14

[chrle]

Re: LG 37lv375s no 24V

It could be that there is no backlight on or INV_ON signal going to that driver board, My guess is that Q502 switches the +24 volts on for the driver board, It looks like the BLON is pin 12 of J1, check the voltage on pins 11~14

pin 14 3.35V
pin 13 2.44v
inv ON 0.03

[R_J]

Re: LG 37lv375s no 24V

There you go, you are missing inverter ON, monitor that pin when you first turn on the tv to see if it comes up to 3 volts then drops. What about pin 11 DET?

[chrle]

Re: LG 37lv375s no 24V

There you go, you are missing inverter ON, monitor that pin when you first turn on the tv to see if it comes up to 3 volts then drops. What about pin 11 DET?

from zero to 0.03V not 3V

pin 11 0V