LG 27GL63T-B completely dead

[Dannyx]

Re: LG 27GL63T-B completely dead

I made measurements on hdmi. All values are normal, resistance high.

I took measurements in all possible places. The L408 has a fairly low resistance of 28 Ohms. I don't know if it's supposed to be that low.

L408 reads ~700kOhms to GND on mine with IC401 removed, so it looks like there's still hope...for mine

I made another discovery after I read about it happening to another chap: I never would've even considered checking that area myself, but SMD cap C508 next to the audio jack is dead-short...I'm not sure if it's supposed to be like that, so if someone else can confirm, that would be great Cheers.

[Draco82]

Re: LG 27GL63T-B completely dead

L408 reads ~700kOhms to GND on mine with IC401 removed, so it looks like there's still hope...for mine

I made another discovery after I read about it happening to another chap: I never would've even considered checking that area myself, but SMD cap C508 next to the audio jack is dead-short...I'm not sure if it's supposed to be like that, so if someone else can confirm, that would be great Cheers.

There is a short on my C508 after removing the c508 there is still a short.

[Dannyx]

Re: LG 27GL63T-B completely dead

There is a short on my C508 after removing the c508 there is still a short.

Could be the connector itself then - I read some people removed it entirely, though I'm not sure it's related to this particular cap - it could be a switch inside the jack. We should measure with a jack inserted, see if it changes anything. I think it's one of those combined optical/analog jacks, so maybe a DC short there is normal....won't know until someone else can confirm, or I do it myself at some point...

EDIT: just in case it helps anyone, this is the closest service manual that I was able to find. The part numbers don't all match unfortunately, so we have to go by similarities, rather than exact components...

[Draco82]

Re: LG 27GL63T-B completely dead

Could be the connector itself then - I read some people removed it entirely, though I'm not sure it's related to this particular cap - it could be a switch inside the jack. We should measure with a jack inserted, see if it changes anything. I think it's one of those combined optical/analog jacks, so maybe a DC short there is normal....won't know until someone else can confirm, or I do it myself at some point...

EDIT: just in case it helps anyone, this is the closest service manual that I was able to find. The part numbers don't all match unfortunately, so we have to go by similarities, rather than exact components...

I also removed the audio jack. It wouldn't boot without a socket either.

[Dannyx]

Re: LG 27GL63T-B completely dead

You also read low ohms on L408, unlike mine, so at this point I'm pretty stuck as to what else you could try...

[Draco82]

Re: LG 27GL63T-B completely dead

You also read low ohms on L408, unlike mine, so at this point I'm pretty stuck as to what else you could try...

Without a schematic or a second working motherboard, I can't check anything else. I did most of the things I could do to get this motherboard to work

[Dannyx]

Re: LG 27GL63T-B completely dead

Without a schematic or a second working motherboard, I can't check anything else. I did most of the things I could do to get this motherboard to work

See if the schematic I posted at #17 helps in the slightest.

[Draco82]

Re: LG 27GL63T-B completely dead

See if the schematic I posted at #17 helps in the slightest.

I looked at this diagram and there are quite a few differences. Voltage measurements are fine, it looks like either the processor or the memory chip is dead.

I think I'll give it a rest with this monitor because the time I lose on repair is not commensurate with the value of this monitor.

[Draco82]

Re: LG 27GL63T-B completely dead

I managed to buy a damaged board with a working processor. After replacing the processor, the monitor turned on. The resistance on the L408 coil must be in Kilo Ohms.

[Draco82]

Re: LG 27GL63T-B completely dead

I managed to buy a damaged board with a working processor. After replacing the processor, the monitor turned on. The resistance on the L408 coil must be in Kilo Ohms.

[Dannyx]

Re: LG 27GL63T-B completely dead

I managed to buy a damaged board with a working processor. After replacing the processor, the monitor turned on. The resistance on the L408 coil must be in Kilo Ohms.

Mine does, so there's still hope

[Dannyx]

Re: LG 27GL63T-B completely dead

No dice. Mine's also dead. I replaced IC401 and restored the missing power rails, but no other reaction, not even the power LED comes on, so either the main IC died like I suspected, or there's a firmware issue

[sofianehack]

Re: LG 27GL63T-B completely dead

Dump

[C:\]

Re: LG 27GL63T-B completely dead

Thank you very much to all for this information, I was able to repair a 27GN750 using the information and service manuals posted here - it shares very similar components and it's IC401 was also dead, output pins 3 and 6 both shorted to ground. Replaced with the recommend 2A replacement here and it powered right on. Now repairing my 27GL63T with a shorted IC401 and no output on IC 402 although receiving 19v. My C508 near the audio Jack is also shorted, haven't tested further or put a jack in yet but will replace my IC401 and 402 and see what I get next. Does anyone have a good model IC for 402? I'm otherwise looking for a similar IACGK online and will help for the best.

[markismus]

Re: LG 27GL63T-B completely dead

You got power going to the board, but nothing happens? Check the crystal. If the crystal isn't working nothing else is either. Check the SPI flash and pull the data sheet. Check if you can update the firmware. Maybe this thing has a TTL port hook up to it and see what happens there. Look at the board and check the little buck converter(s) maybe one is shorted to GND.

I've added 2 Hi-res photo's. (How do you take a photograph from a PCB without the glare?)



The |AKX buck regulator generates 2.0V falling down to 0.89V and continuing on the L409 coil. It's too hot to touch.
The |AGC step down converter generates 0V on the L410 coil.
The |AQT step down converter generates 3.33V on the L405 coil.

I've added the datasheet of these three. It seems that only the |AQT is working as expected. I've ordered the other two from AliExpress. Nor the L410 coil nor any but connection 4 (GRD) of |AGCK showed a short to GRD.


The crystal X200 is tagged SC12.000 A1930. My multimeter only goes to 10MHz, so I only see the 50Hz of the power net. I assume it's 12MHz. Can't find a way to check it yet. Is there sense in just swapping it out with another and see what happens?

P200 could be the TTL port. Not quite sure how to hook it up yet, though.

Any idea what part could be the SPI flash? IC600 has MPS1928 on it, which seems to be a voltage regulator. IC101 is quite unreadable. IC201 and IC202, too.

[markismus]

Re: LG 27GL63T-B completely dead

I've used my magnifier and the IC codes are:

IC101:
SD642AO or SD642A0
TI 69A680I G4 of TI 69A68OI G4

IC201:
FT24C32A
9eHBAC

IC202:
BE1941
25Q80CSIG or 25080CSIG

IC500:
TPA6138
98TG4
CISZ

IC600:
MPS1928
MP3378R
K4871538X

[JoeDocked]

Re: LG 27GL63T-B completely dead

My LG 27gl650f also died suddenly. I don't have a thermal imaging camera, but by touching the various components with my finger, I noticed that the IC600 gets hot after a few seconds. Have any of you had problems with the IC600 and managed to solve it? In the meantime I will order mp3378r and try to replace it

[C:\]

Re: LG 27GL63T-B completely dead

My LG 27gl650f also died suddenly. I don't have a thermal imaging camera, but by touching the various components with my finger, I noticed that the IC600 gets hot after a few seconds. Have any of you had problems with the IC600 and managed to solve it? In the meantime I will order mp3378r and try to replace it

LG uses different IC numbers across different models on the pcb even if the circuits or in this case buck converters are laid out the same using the same parts. What is the IC number on top of the chip and what is it a part of/goes to it? If it's another buck converter it likely has the same failure issue as our AGC and AKX IC's, common issue in this design across all LG models containing it it seems. Should be able to look up the ic and find its outputs then troubleshoot similarly. Probably another short if its hot. Can also check if the LC coils are shorted coming off of it if buck.

[voveo]

Hi all! Can someone measure the resistance of the L407 and L408 power phases on the working board? thanks in advance, I have the following power supply on the phase resistance board: L407 340 ohm L408 39 ohm

[hukkaja]

Hi! I have two of these monitors, last night i turned my pc off. Today, when turning on the pc, one of the monitors is dead aswell. Lifetime of the monitor: 2 years, 7 months. Utterly disappointed. I have minimal electric experience. I ordered the new IC401 chip to try out if that solves the issue. How would one approach desoldering, soldering the new chip? It is 2mm long, has 4 pins on each side. Seems really precise work. The chip has IAKXM written on it that i hope is the culprit. Will add some images soon. All i can say that i truly like these monitors, brilliant. 144hz, 27" and 1080p. Perfect for my eyes and usage case. I am an all-rounder pc user.