Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

[Moosiv]

Morning guys, I've got this gaming laptop which attempts to boot. Plugged into DPS it draws 200ma for about 10 seconds and switches off.
On boot I get5v and 3v always. First noticed no CPU power rails although 19v is sat at the caps ready to go. Then noticed no RAM voltage which I figure needs to be active before the cpu power rail. I can't find any shorts on the board which is clean and undamaged. High and low side mosfets are ok, like I say, I can't actually find anything out of the ordinary. The RAM power IC has 5v coming in but nothing to S3&S5 which should enable the chip. See attached. I have a board view which I'll also attach but no schematic. At this point I'm stumped, if anyone is able to point me the right direction I'd appreciate it. TIA

[reformatt]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

Seems to me you need PU21 to enable 1.2V, which in turn is dependent on 2.5V from PU25. Check for presence of +3VSUS and +5VSUS, PM_SLP_S4# etc.

[Moosiv]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

Thanks for taking the time to help me.

PU21
PIN 1 2.5V_MEM_PWRGD 3.4V
PIN 2 PM_SLP_S4 0V
PIN 5 +3VSUS 3.4V

PU25
PIN 5 3VSUS 3.4V
PIN 6 5VSUS 5.24V
PIN 7 2V5_MEM_PWRGD 3.4V
PIN 8 2V5_MEM_EN 3.32V

[Moosiv]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

The 2.5v on PU21 seems high?

[reformatt]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

PU21 seems to be an AND gate, and pin1/2 are the inputs. Checked another similar schematic from MSI and it looks quite similar.

https://www.badcaps.net/forum/attach...3&d=1634763194

2.5V_MEM_PWRGD is a logic level and should be high. PM_SLP_S4# however should be high and it isn't, hence why you have no enable for the 1.2V RAM supply. Going off that schematic above, you need your CPU Vcore active before PM_SLP_S4# goes high.

[reformatt]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

If there is no obvious damage, then check your resistance to ground of the +1.05V supply. Often this is a dead PCH if it's short or very low impedance.

[Moosiv]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

Hi, thanks dude!

I've checked PU24 output to PL15 and I get 1.05V. The coil measure 61ohms to ground.

I've read gen 1-5 intel cpu have 11+1 pre requisites for PM_SLP_S4 to be produced by the CPU and Gen 6 upwards 13+1 to be produced by PCH. I can find the list of pre requisite for 11+1 but not 13+1 - I think this could be helpful if you have a source I could use. Here's a link to the 11+1 I found. Would you agree or am I veering off?

https://www.it-tech.com.au/mac-q-a/pm-slp-s4-l-timing/

[reformatt]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

Sitting there looking at that sequence thinking that's back to front. Ha, in that schematic they have power sequences for G3-->S0 AND S0-->G3. So sorry, I was looking at the latter, which is the power down sequence. Of course Vcore comes up after RAM, brain was not in gear this morning.

So the G3-->S0 sequence in that other model will be pretty much identical. Some things to check on board after power button press:

SUS_ON
+3VSUS/+5VSUS
+1_8VSUS
+1.05VSUS
SUSPWROK
RSMRST#
AC_PRESENT
PM_PWRBTN#
PM_SLP_S5#

[Moosiv]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

SUS_ON - 3.32
+3VSUS/+5VSUS - 3.42/5.28
+1_8VSUS - 1.8
+1.05VSUS - 1.05
SUSPWROK - 3.05
RSMRST# - 3.26
AC_PRESENT - 3.36
PM_PWRBTN# - 3.32
PM_SLP_S5# - no results found searching board view

I hope the above can help some how. I starting to wonder if it's worth removing the bios chip, backing it up and re flashing it? What do you think?

[reformatt]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

PM_SLP_S4# is generated by the PCH. With the limited info publicly available, it appears as if you have everything you need so far, so back to the PM_SLP_S4 pre-requisites then (BATLOW etc). You can certainly try a donor BIOS (remember to back up your original one though), won't hurt at this point.

BIOS is read much later in the sequence but it won't hurt to try. I am always suspicious of a dead PCH with things like this though.

[Moosiv]

Re: Msi gs75 stealth - ms-17g11 ms-17g1 rev1.1

Thanks dude. Bios flash didn't change anything.

I've sourced a board in the state's.

Thanks for your help 👊