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LG 27GL63T-B completely dead

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  • voveo
    replied
    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
    Last edited by voveo; 12-05-2023, 12:46 PM.

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  • C:\
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by JoeDocked View Post
    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.

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  • JoeDocked
    replied
    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

    Leave a comment:


  • markismus
    replied
    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

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  • markismus
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by CapLeaker View Post
    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.
    Attached Files

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  • C:\
    replied
    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.

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  • sofianehack
    replied
    Re: LG 27GL63T-B completely dead

    Dump
    Attached Files

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  • Dannyx
    replied
    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

    Leave a comment:


  • Dannyx
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Draco82 View Post
    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

    Leave a comment:


  • Draco82
    replied
    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.

    Leave a comment:


  • Draco82
    replied
    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.
    Attached Files

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  • Draco82
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Dannyx View Post
    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.

    Leave a comment:


  • Dannyx
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Draco82 View Post
    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.

    Leave a comment:


  • Draco82
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Dannyx View Post
    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

    Leave a comment:


  • Dannyx
    replied
    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...

    Leave a comment:


  • Draco82
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Dannyx View Post
    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.

    Leave a comment:


  • Dannyx
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Draco82 View Post
    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...
    Attached Files
    Last edited by Dannyx; 03-20-2023, 02:40 PM.

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  • Draco82
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Dannyx View Post
    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.

    Leave a comment:


  • Dannyx
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by Draco82 View Post
    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.

    Leave a comment:


  • Draco82
    replied
    Re: LG 27GL63T-B completely dead

    Originally posted by lotas View Post
    Yes, maybe the firmware has crashed here, maybe the processor, check the hdmi inputs, ... for a short or low resistance.
    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.
    Last edited by Draco82; 03-20-2023, 07:44 AM.

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