Re: LG 42LM615S No picture, sound and backlight working

[B]Alright people, thank you all, I solved the problem.[/B]

As I suspected, the problem was a shorted SMD capacitor on power rail of the right driver board of the LCD panel. But since there was at least 5 or 6 of those (judging by its size those are 100n decoupling caps), I had to desolder one after another and measure which one is actually shorted. Fortunately I found the little bastard on 3rd soldering so I didn't have to go through all of them. I probed the pads for any other possible shorts and it was alright...

Re: LG 42LM615S No picture, sound and backlight working

Okay so I haven't tested the LVDS voltages but I probed the driver board of the LCD panel (which i mistakenly called a buffer board before). And I found something interesting. Some of the SMD caps seem to be shorted, the multimeter reads 0 ohms when testing them. But that's only on the right board. The left board is basically a mirrored version of the right board, so I tried to measure the same caps on the left board and it reads 1.3kOhm there. Not sure which one I should trust but both seem a bit suspicious to me because they're...

Re: LG 42LM615S No picture, sound and backlight working



Well, It seems that I will have to wait till I get an oscilloscope, I checked the SM schematics if there's any possible obstacle in the way of the LVDS lines but I found it goes straight from the SoC to the connector, with no resistors or anything. So either the integrated output stage of the LVDS section is shorted in that one pair which reads 0 or it's unused... No idea. But why would they trace it to the connector if it was unused?

I'll try to stick some needles on the multimeter probes and...

Re: LG 42LM615S No picture, sound and backlight working



Thanks for advice, I wouldn't have thought the multimeter will read anything at all at god knows what waveform at high frequencies. I just measured 5 out of 12 pairs of LVDS RX pins, specifically

RXA3+(14) RXACK+(16) RXA2+(19) RXA1+(22) RXA0+(24)
RXA3-(15) RXACK-(17) RXA2-(20) RXA1-(23) RXA0-(25)

All of them measured 1140 to 1270mV, except for RXA0+ and RXA0- which sit both at 2mV. I don't have a good access to the rest of the pins because the solder...

Hi all,

I'm new to this forum so sorry if I missed any important info. Have read the rules and all. So---

Recently I found this 42" LG TV in a trash yard, it looked nice and most importantly the screen was not cracked so I took it home. Upon connecting the TV to mains, it turned on, the Standby LED blinked 2 times (I read this is normal as the TV boots up) and I managed to tune in local TV stations over DVB-T. The sound works, but the LCD panel doesn't. It's continuously black from the start-up. The backlight glows and occassionally changes its brightness depending...

Re: New Members - please post your introductions here

Hello everyone,

so to start off, my name is [B]Marek[/B] and I'm from the [B]Czech republic[/B]. I'm 20 years old and I've been engaging myself in electroncis since I was about 3 years old. My beginnings were more of silly playing around with electronics, batteries and light bulbs but as I was getting older, my knowledge about electronics started to develop in a more meaningful and useful way. I've always wanted to work as an electrician or a serviceman of electronics. At around 2010 my interest extended to the...