LG LED 42LW5500-ZE powers on, but no picture or sound

[Trofazni]

I got this tv few days ago and i'm stuck. Client told me that the picture at first appeared as whitenoise, and then nothing.
When I plug it in, it has 3v3stb, and reacts to remote controller, and pwr on gets 3v3 high, standby light turns from yellow to white, and relay clicks and now we have all voltages, but no backlight, no sound, no picture...
Any references? Thanks

[Andrew F. Ali]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Take a look at the T-CON Bd. Look for a fuse where the cables from the Main Bd connects to the T-CON Bd. See if there is continuity across the fuse.

[budm]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

I got this tv few days ago and i'm stuck. Client told me that the picture at first appeared as whitenoise, and then nothing.
When I plug it in, it has 3v3stb, and reacts to remote controller, and pwr on gets 3v3 high, standby light turns from yellow to white, and relay clicks and now we have all voltages, but no backlight, no sound, no picture...
Any references? Thanks

We are still missing more information such as the BL-ON and Dim control signals

[nomoresonys]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

What you getting for drv_on pin, with tv plugged in and when you hit power button?

[Trofazni]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Take a look at the T-CON Bd. Look for a fuse where the cables from the Main Bd connects to the T-CON Bd. See if there is continuity across the fuse.

Fuse is ok, but no voltage is present across the filter cap...

[vinceroger69]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

can you do the test as requested in post 3 thanks

[Trofazni]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

We are still missing more information such as the BL-ON and Dim control signals

I've measured it.. errror 0V, PWM 3V1, DRV on 0v, VSYNC 0V...

[vinceroger69]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

drive on i would guess should go high in voltage so maybe a main board issue i will see if we can find a service manual for this set what is the power supply and main board numbers
i wonder if the main baord has been replaced before as never seen a original one with green pen marker writing on it

[Trofazni]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

drive on i would guess should go high in voltage so maybe a main board issue i will see if we can find a service manual for this set what is the power supply and main board numbers
i wonder if the main baord has been replaced before as never seen a original one with green pen marker writing on it

MB eax64294002
PSU eax62865401

Thank You!
I also suspect on MB, but can not find another in my country, if we can fix it, lets do it

[nomoresonys]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Test connector going from powersupply to mainboard for continuity, careful not to spread out the connector ends.

[vinceroger69]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

link too the service manual
https://www.manualslib.com/manual/12...-32lw5500.html

[Trofazni]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Test connector going from powersupply to mainboard for continuity, careful not to spread out the connector ends.

No, not the problem there...

Any other ideas?

[nomoresonys]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Looks like the mainboard isn't sending drv_on signal to turn on backlights.

[vinceroger69]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

A lot of lgs were seeing in threads i notice are failing due to bga soldering and a reflow seems to get them working but not sure what ic the drv on signal comes from? is it the eeprom/spi flash or one of the large bga ics?

[nomoresonys]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

In the manual from manualslib. all the pages from 30 on up don't show any info. not sure why.

[WildPuppy]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Here:

[Trofazni]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

A lot of lgs were seeing in threads i notice are failing due to bga soldering and a reflow seems to get them working but not sure what ic the drv on signal comes from? is it the eeprom/spi flash or one of the large bga ics?

Pwr on comes from eeprom, but I really do not know for the drv on signal.. If it comes from bga, I will try to reflow it, but I dont wanna reflow if it does not come from cpu.. Manual is ok, i have downloaded it and its fine..

[Andrew F. Ali]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

A lot of lgs were seeing in threads i notice are failing due to bga soldering and a reflow seems to get them working but not sure what ic the drv on signal comes from? is it the eeprom/spi flash or one of the large bga ics?

+10...Yes it is true. A lot of LGs have a BGA issue and reflowing with a hot air station at 350C for ten (10) minutes worked for me on many LGs recently, especially those LW series. Keep the hot air steady on the BGA chip. Of course remove the heatsink and tape from off the IC. Before reinstalling verify none of the components under the chip has been moved or shifted.

[vinceroger69]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Here:

Thanks all the pages open fine in this pdf ive added it to my collection

[WildPuppy]

Re: LG LED 42LW5500-ZE powers on, but no picture or sound

Happy to be of service.