LG 27GL63T-B completely dead

[sofianehack]

Re: LG 27GL63T-B completely dead

Dump

[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

[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

[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.

[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.

[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

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

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

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

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

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

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

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.

[lotas]

Re: LG 27GL63T-B completely dead

Yes, maybe the firmware has crashed here, maybe the processor, check the hdmi inputs, ... for a short or low resistance.

[Draco82]

Re: LG 27GL63T-B completely dead

Hello and welcome. I got the same model for repair. Initial Diagnosis no voltage on IC401, replaced with a new voltage returned to L408 - 1.8V L407 -1.2V. However, the monitor does not turn on. The rest of the voltages L405 - 3.3V, L601 - 5V, L602 - 19V, L410 - 0V (IC402 also replaced) Is it possible that the processor has failed? Current consumption 0.055A. No response to the switch, the status LED is off.

[Dannyx]

Re: LG 27GL63T-B completely dead

Hi guys. Having the exact same issue: IC401 felt slightly hot, so I removed it and indeed its ground pins were BOTH shorted to the 2 outputs. Trouble is, at some point, as I was messing with the board, trying to figure out what's shorted, I measured 5v on one of the outputs of IC401 (that's normally supposed to be 1.2/1.8v), so I'm afraid it may have took out the main IC too, although the resistances on both coils of IC401 (with the chip removed) are reasonably high and the main IC itself never got hot, so hopefully it survived. I'm waiting for my replacement IC401 to arrive...

If anyone has a working board and could take some measurements of the "correct" voltages in both the on and standby states, that would be great.

[rodeo65]

Re: LG 27GL63T-B completely dead

Hi all,

have a LG 27GL63T as well with IC401 broken. There was no 1.2V and 1.8V, but the IC did not get hot.
Ordered some new MP9148GJ-Z MP9148GJ IAKX SOT23-8 from Aliexpress since local suppliers had no stock.

Data sheet:
https://www.monolithicpower.com/en/d...ument_id/1013/

With a bit of effort and lots of flux the chip was replaced. Monitor worked fine again straight after that. I did not verify the voltages afterwards to be honest.
Seems that this board design is quite bad looking at all the problems people have with it.

On some repair websites there was also a reference to replacing the 12MHz xtal should it still fail when 1.2V and 1.8V are back after IC401 replacement.
I think next time should this IC401 fail, I'll replace the chip with two separate buck converters of 1.2V and 1.8V that can better cope with the currents needed.

hope this helps anyone.

12Mhz xtal is what please? Do you have link to aliexpress for example?

Thanks

Edit: no need to send link - my stupidity

[rodeo65]

Re: LG 27GL63T-B completely dead

Guys who replaced ic401 and succeeded had you remove audio jack too? I removed it before but cannot find replacement on market. May it be cause why it is still dead?

Btw still waiting for new ic402 being shipped.

[inv4der]

Re: LG 27GL63T-B completely dead

Hello, what should be the voltage on the coils L407, L408 and L410 ??