MSI GS75 No Power

[Astray]

Hello, working on a laptop (MSI GS75 9SG-242US, Core i7-9750H, 2080 Max Q) and after replacing the screen and forgetting to disconnect the battery prior, I have no visible indications of power anywhere. It was working perfectly fine prior to the screen removal and replacement. Checked the motherboard PCB visually near the LCD connectors and didn't really see any indications of damaged surface mounted components but haven't looked under a microscope yet.

Battery charging light isn't turning on when plugged in and pressing the button does nothing regardless of being on battery power or AC adapter power. Voltage from power adapter is around 20V as expected, battery doesn't seem to have any voltage after taking my voltmeter to it, so possibly the battery could have just coincidentally died but I'm unsure at the moment without a replacement laying around. Also likely I can't read the battery voltage properly given the control circuitry usually involved with these things.

I've tried disconnecting everything (including CMOS) and removing the motherboard PCB before reassembling after at least 1 hour to give the system time to reset but that hasn't accomplished anything.

Anything I should specifically looking for that I might have missed at this point? I'm finding it hard to believe MSI really manufactures their screens in such a way that they will damage other components if you leave the battery connected while replacing it. I was pretty careful with the removal of the connector and installing into the new screen. Like it shouldn't even have power provided to any of the pins until the machine is turned on anyways right?


It also appears that there's an EC chip that's gotten fried. It had kapton tape on the chip and there's a noticeable bubble inside the kapton tape that I don't remember being there and it has a pretty distinct smell of something that got burned. Has the letters "ene" on it and "KB9028Q C" the rest is difficult to read, not sure if they're relevant.

I'm unsure what my next diagnostic steps would be, I'm not sure what points I should be testing with a voltmeter and the values I should be looking for. It's likely the KB9028Q C chip but even if I'm able to get a replacement I'm unsure how to program it and what other chips could've been damaged and to check them properly.

I definitely want to perform the repair on my own but I might need a bit of handholding/guidance through this process so I can do this correctly. Thanks!

[mon2]

Post a pic of the ENE part. If with a bubble or crack, it is dead and needs to be replaced. This is a stand alone 8051 microcontroller with firmware needed to monitor the on off button; keyboard; etc.

[Astray]

Here's a photo of it. The mark is so small but before I took off the kapton tape there was a bubble in the tape right where that one mark is in near the center of the chip.

[mon2]

Hot air can cause moisture to turn to steam and popcorn the ic. This kills the ic.

[Astray]

Well it was working prior to the LCD screen replacement so I'm guessing me doing that replacement without disconnecting the battery caused some kind of short somewhere and blew it up, unless I was just really unlucky with the timing here and it's a huge unfortunate coincidence.

Either way that is likely the culprit I'm guessing, but I'm worried something else may have been damaged once the IC died, or whatever caused the IC to die needs to be fixed before replacing the IC.

Not sure what connections I should be testing nor what locations and values I would need to be looking for to test them for that either.

I was going to plug in power and the battery again and take a look with my thermal camera to see what information that might provide.

I saw some youtube videos by Northridge Fix of him fixing a one generation newer model that had the same issue and the fix was just replacing the super IO IC use the thermal camera and feeding voltage at a certain location to test.

[reformatt]

+19V is usually present on the LCD connector in most designs regardless of power state, not just MSI. So always a good idea to remove the battery for any laptop when plugging in any connector. Switching this voltage isn't required as the LCD connector is not considered hot plug, and LCD control is from other signals.

I'd first be checking your +19V power rail isn't shorted to ground. Check it at the current sense resistor PR251 (or on pin 40 of CN11). If that's ok, then check for presence of +3VALW for the EC at PU26 pin 3 or PC225. You should at least have +3V on one side of your power button as a quick check.

[Astray]

+19V is usually present on the LCD connector in most designs regardless of power state, not just MSI. So always a good idea to remove the battery for any laptop when plugging in any connector. Switching this voltage isn't required as the LCD connector is not considered hot plug, and LCD control is from other signals.

I'd first be checking your +19V power rail isn't shorted to ground. Check it at the current sense resistor PR251 (or on pin 40 of CN11). If that's ok, then check for presence of +3VALW for the EC at PU26 pin 3 or PC225. You should at least have +3V on one side of your power button as a quick check.

Hi, thanks for sharing that information! I'm sorry but I'm pretty new to this and unsure what the current sense resistor PR251 is or where to find it on the board (or what CN11 is). Also don't know what +3VALW is (I'm assuming some kind of 3V power rail), what PU26 is or PC225 so if you could clarify or point in the direction of somewhere I could learn I would appreciate it.

Also some additional information I obtained after using my thermal imaging camera, there's a very small chip that is getting incredibly hot (the EC is also becoming fairly warm but not nearly as hot as the smaller chip) when I plug in the power adapter to the board. The thermal imaging isn't aligned properly so I highlighted the chip in a normal photo, please see below.

[mcplslg123]

reformatt has alraedy guided you. If u dont understand how to act on it,best advise is to take it to an expert. The smaller chip is very likely to be your 3V/5V controller. When a screen is plugged/unpulugged with battery connected, usually damage is not limited to one component. You may be having a shorted +19V rail as well as +3V rail. The EC and 3V/5V controller is bad for sure. Whether anything more is damaged can be measured by checking resistance to GND on respective rails only after removing those two components. So once again i repeat,if you dont have the expertise,take it to an expert. Moreover, The EC needs to be programmed after replacement for which you need a special programmer like SVOD etc.

[Astray]

reformatt has alraedy guided you. If u dont understand how to act on it,best advise is to take it to an expert. The smaller chip is very likely to be your 3V/5V controller. When a screen is plugged/unpulugged with battery connected, usually damage is not limited to one component. You may be having a shorted +19V rail as well as +3V rail. The EC and 3V/5V controller is bad for sure. Whether anything more is damaged can be measured by checking resistance to GND on respective rails only after removing those two components. So once again i repeat,if you dont have the expertise,take it to an expert. Moreover, The EC needs to be programmed after replacement for which you need a special programmer like SVOD etc.

I understand that he has assisted me but isn't this supposed to be a place to learn? How do I identify which rails are which when I don't have a schematic? Can you direct me to a post or something that teaches me how to identify the rails and components I need to be testing?

Everyone has to start somewhere. I still need to get a hot air station or be very careful with my heat gun so I can remove the chips as well. Again, I am completely new to this level of repair and I want to learn so please bear with me.

I found a large resistor with R005 on top of it near the power connections for the battery and AC adapter with PR251 on the silkscreen very close to it, and there's a resistor with PC225 near the chip labeled
1225C
T1 8B8
A5N6

I'm guessing these are the components I need to be concerned about?

[reformatt]

Fair enough. The references are component designators in the schematic/boardview, and on the silkscreen of the board. Manufacturers don't release this information willingly. If it's in the public domain, it's only because it's been obtained unofficially (stolen or leaked).

Now for this model, I believe it's a MS-17G11 motherboard (update if this isn't correct). Boardview is available for that on this forum - it's in CAD format so you'll need to use OpenBoardview for example to view it. There isn't a schematic, however the design is pretty similar to other MSI models that are available (like the MS16-J9 motherboard which is available). Component designators might differ, but the basic design is the same for broad troubleshooting.

From your thermal images, it seems that PU26 is getting hot which is the 3V/5V buck controller (so I'm assuming the 19V rail isn't shorted as this is getting power at least). Check pin 3 here for a short (or the capacitor PC225). Also check and report resistance to ground for PL19.

You can use PU4 as a reference in the MS16-J9 schematic. Pin 3 is VREG3, which is an LDO output that feeds things like the EC.

[Dcortest]

it's a TPS1225C and provide 3V/5V always, I have a similar issue with a GS75 and had replaced that buck converter and also ENE chip

[Astray]

Fair enough. The references are component designators in the schematic/boardview, and on the silkscreen of the board. Manufacturers don't release this information willingly. If it's in the public domain, it's only because it's been obtained unofficially (stolen or leaked).

Now for this model, I believe it's a MS-17G11 motherboard (update if this isn't correct). Boardview is available for that on this forum - it's in CAD format so you'll need to use OpenBoardview for example to view it. There isn't a schematic, however the design is pretty similar to other MSI models that are available (like the MS16-J9 motherboard which is available). Component designators might differ, but the basic design is the same for broad troubleshooting.

From your thermal images, it seems that PU26 is getting hot which is the 3V/5V buck controller (so I'm assuming the 19V rail isn't shorted as this is getting power at least). Check pin 3 here for a short (or the capacitor PC225). Also check and report resistance to ground for PL19.

You can use PU4 as a reference in the MS16-J9 schematic. Pin 3 is VREG3, which is an LDO output that feeds things like the EC.

Hello again!

Sorry I kind of let this thread die, I've been busy IRL and also needed to acquire equipment and parts to do this repair.

I checked PR251 and confirmed there's no short there.

I checked +3VALW on PC225 and found no voltage there as expected. There wasn't a short on Pin 3 of PU26/PC225 either.

Resistance of PL19 Pin 1 (SW_3V3) and Pin 2 (+3VSUS) was 2.18k ohms to the ground pin of PC225. If I tried using the grounded plated screw holes I did get different resistance values around 350 ohms on both pins some how depending on which screw hole I checked. Not sure if that matters.

Not entirely sure what you meant by using PU4 as a reference. This board is definitely the MS-17G11 or some variant of it so the board view CAD I found seems very accurate.

I believe my next steps are to remove the buck converter and ENE chip and soldering new ones in their place at this point right or is there anything else I should test so I don't go ruining the replacements I picked up. I had someone preprogram the ENE for me ahead of time.

[Astray]

So I removed a 3V/5V LDO (TPS1225C) from my board but accidentally bumped many of the smaller resistors near when removing and now I have no idea which one is which and they all have different values. I'm fairly certain 2 are in the correct location because they didn't move too much (not 100% though), but the other two I have no idea. One is 101kOhm and the other is 24.3kOhm. I have the board view of this motherboard but it doesn't have the resistance values. Need the resistances on PR258, PR261, PR265, and PR271. Anyone know where that info might be available? There's no schematics for this particular board based on my google and forum searching.

[mcplslg123]

Compare with any schematic which has TPS51225C to get the values of resistor. Just note the pin number of IC where the connection goes and compare it with any other schematic.
Dell cedar 13269-1 has this IC and both schematic and boardview are available on this forum. Hope this helps.

[Astray]

Compare with any schematic which has TPS51225C to get the values of resistor. Just note the pin number of IC where the connection goes and compare it with any other schematic.
Dell cedar 13269-1 has this IC and both schematic and boardview are available on this forum. Hope this helps.

I actually checked a schematic of another MSI laptop board (MS-17F2) with this component beforehand and the resistance values in the schematic were different from what I'm measuring on these resistors unfortunately so that doesn't seem like a viable alternative.

There's a 100kOhm on the SUS_ON net (pin 6 and pin 20) which matches the 101kOhm I have, but the resistor for pin 1 is 130kOhms on that schematic and I have a 24.3kOhm resistor. The other resistors seem in line but are different mine as well at 10kOhm for Pin 2 to Gnd (31.6kOhm for PR271 is what I measured) and 15.4kOhm from pin 2 to +5VSUS (20kOhm for PR265 measured). This assumes those didn't move accidentally without me noticing.

[Astray]

Anyone else possibly have information on these resistance values? I'm getting desperate lol

[Dcortest]

maybe I can help you, I got a MSI 17G3 with the same 3v/5V regulator. I'll measure all resistance when I arrive at home

[Astray]

maybe I can help you, I got a MSI 17G3 with the same 3v/5V regulator. I'll measure all resistance when I arrive at home

That would be extremely helpful, thank you so much!

[ResoluteHawk]

Your 3V/5V regulator very likely is not bad and is not the cause of your problem. It's not a bad idea to replace it along with the Super IO chip, but the TI1225 is heating up because the output is shorted, thus you're seeing a symptom of what the actual problem is.

Take the ENE Super IO chip off the board and replace it. You'll have to get one that is either already preprogrammed or program it yourself using the firmware on MSI's website and an ENE programmer.

When you're doing board repair/diagnostics, you must know that just because a component is heating up does NOT always mean that it is bad.

Also, remember that values of resistors will not measure correctly if they are measured in circuit. The best way to measure components like resistors and capacitors is to either use an LCR meter or you take them off the board and carefully probe them with a multimeter in the respective mode.

[Astray]

Your 3V/5V regulator very likely is not bad and is not the cause of your problem. It's not a bad idea to replace it along with the Super IO chip, but the TI1225 is heating up because the output is shorted, thus you're seeing a symptom of what the actual problem is.

Take the ENE Super IO chip off the board and replace it. You'll have to get one that is either already preprogrammed or program it yourself using the firmware on MSI's website and an ENE programmer.

When you're doing board repair/diagnostics, you must know that just because a component is heating up does NOT always mean that it is bad.

Also, remember that values of resistors will not measure correctly if they are measured in circuit. The best way to measure components like resistors and capacitors is to either use an LCR meter or you take them off the board and carefully probe them with a multimeter in the respective mode.

The TI1225 was cheap enough that I just bought it to replace regardless just to be safe for the repair.

I got two of each of each chip, and had the ENE preprogrammed and ready to go, though MSI built in an EC reset function so it might even have a chip somewhere that will auto program the ENE if it's functioning properly?

And good thought about the resistors, but wouldn't that only matter if they're in parallel with other resistors? If they're not then the values should be okay I would think right? The resistors have already been removed from the board regardless because of my carelessness removing the TI1225 haha.