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jimanez11 03-10-2022 04:39 PM

MSI PS63 Modern MS-16S1 - No Power
Have a MSI PS63 Modern with a board number of MS-16S11. Havent been able to find schematics or boardview for this machine, but would love to try to get it fixed.

When the power button is pressed, the machine attempts to boot - keyboard backlight turns on, then there is an audible click and the board reverts to a power off state. Press the power button again and the same thing happens. Have pulled the board from the machine trying to locate the clicking noise by sound, but it appears to be coming from everywhere on the board and I cant pinpoint its location.

The board is getting 19 volts all over the place and the 3v and 5v always on are both present. Nothing is getting hot when the power button is pressed either.

When the power button is pressed, the following power rails come on (measured at coils):
- 3.3v (sitting at 1.04v before power button is pressed)
- 5v
- 1.8v
- 0.8v
- 1.2v
- Some of the CPU rails appear to receive power as well (0.8v and 1.2v)

The only rails that do not show voltage when the button is pressed appear to supply the GPU and the onboard RAM (I think) modules (Samsung 825 - K4G80325FB-HC25 chips).

The coil that supplies the RAM voltages (PL1) is measuring at ~80 ohms to ground
The two coils that supply the GPU are Measuring at 1.5 ohms to ground which is a potential cause for concern, but have seen very low resistance on newer GPUs, so not sure if this is shorted.

I am not sure if this is a bad mosfet or a bad coil, or a bad GPU or maybe a sensor of some kind that is getting triggered, but without a schematic or boardview I am kind of lost. What would the next steps be?

I have done a visual inspection and the solder joints on all mosfets look pretty good. Should I lift the coils that are not receiving voltage and see if the clicking remains? This would at least narrow it down to which side of the coil the issue is occurring.

As always, any advice is appreciated and looking forward to getting this computer up and running if its repairable.

mcplslg123 03-10-2022 10:53 PM

Re: MSI PS63 Modern MS-16S1 - No Power
Yes, try lifting the gpu coils and see if switching stabilises. resistance of 1.5 Ohms on newer gpu is ok.

piernov 03-11-2022 07:11 AM

Re: MSI PS63 Modern MS-16S1 - No Power
Need to make sure no short to ground on power rails that come up during POST, such as iGPU VCore, LCD power rail and possibly backlight power rail.

jimanez11 03-11-2022 04:06 PM

Re: MSI PS63 Modern MS-16S1 - No Power
Thanks mcplslg123 and piernov for the responses and suggestions. I will try lifting the GPU coils and see if anything changes.
Piernov - how would I go about testing the downstream side of the power rails that do come up for a short? I can inject voltage but without knowing the voltages that are expected on the coils, that would be a toss-up and dont want to fry anything. Should I lift the coils and see if the resistance drops or should I take a look at voltage regulator output pins? Will try to trace back the LCD power rail and see if I can locate the iGPU VCore rails as well and will post results.

jimanez11 03-11-2022 08:45 PM

Re: MSI PS63 Modern MS-16S1 - No Power
Scratch that Piernov - misread your reply. Think you meant that I need to check for shorts on the rails that are enabled before computer posts. My fault - has been a long day!

jimanez11 03-18-2022 01:38 PM

Re: MSI PS63 Modern MS-16S1 - No Power
So - was taking some additional voltage readings on other lines that would come during post as Piernov suggested when my 19v completely went away. I didnt bridge anything or inadvertantly short anything with my probes, so maybe the chip was on the verge of failure which was causing the initial issues? Either way, this triggered the shut-off protection in the power supply which pointed to a short on the main rail, which was now reading 80 ohms to ground. After some more probing, was able to find a mosfet that was shorted and after it was removed from the board, short is gone.

This is the same mosfet that supplies power to the onboard GPU RAM and that rail previously never came on. It was reading ~80 ohms to ground at the coil before the loss of the 19v and continues to do so. Just ordered a replacement from Mouser and fingers crossed that this didn't shoot 19v directly into these chips.

jimanez11 03-21-2022 09:20 PM

Re: MSI PS63 Modern MS-16S1 - No Power
1 Attachment(s)
Had some time to do some tests tonight after replacing the shorted mosfet on the 19v rail. Lifted the coil for the 1.05SUS power rail (at least to the best I can tell based on a schematic for a MS-16R11 which is somewhat similar) and the immediate power down / clicking issue went away. The chip that generates this rail is an NB685GQ (datasheet is included here as well). This rail is reading at 300 ohms to ground on the consumer side when lifted and 270 ohms to ground when soldered on to the pad. Not sure if this would be a case where voltage injection would be useful if it is a partial short? I do have a bench power supply, but generally refrain from injecting voltage unless I am guided that direction by someone who knows more.

Any next steps are appreciated.

jimanez11 03-21-2022 11:09 PM

Re: MSI PS63 Modern MS-16S1 - No Power
So yeah - dead PCH integrated with CPU = no hope?

jimanez11 03-22-2022 08:14 AM

Re: MSI PS63 Modern MS-16S1 - No Power
Scratch my last two posts about the rail being the 1.05vSUS rail. It is the 1.2v RAM power rail that, when lifted, resulted in the clicking noise and power down issue to go away.

The measurements are the same - measuring 270 ohms to ground.

The rail blinks on for a moment and gets to 1.2v, then a click, and an immediate shutdown.

Voltages on the NB685GQ look good, so no issues in actually generating the rail. But - there is an OTW pin that gets to about .750v after a few power on attempts and starts at .250v on a cold boot.

Ill take a look and see what else this rail powers based on other boards schematics that could be causing the issue, but is there anything additional I can do to get to the root of the problem?

jimanez11 03-30-2022 09:08 AM

Re: MSI PS63 Modern MS-16S1 - No Power
1 Attachment(s)
Was able to take some measurements from PU15 between the power on button being pressed and the system shutting down. The datasheet for this has also been attached to the post.

This is an NB685GQ - got the following results on the pins.

Pin 1 (VIN) - 19.9v
Pin 2 (PGND) - 0v
Pin 3 (3v3) - 3.3v
Pin 4 (AGND) - 0v
Pin 5 (VTT) - .594v
Pin 6 (VDDQ) - 1.19v
Pin 7 (VTTREF) - .594v
Pin 8 (VTTS) - .594v
Pin 9 (SW) - 1.19v
Pin 10 (BST) - 4.4v - This seems high?
Pin 11 (OTW) - .268v - .750v
Pin 12 (PG) - 2.9v
Pin 13 (FB) - .594v
Pin 14 (Mode) - 0v
Pin 15 (EN2) - 3.2v
Pin 16 (EN1) - 3.2v

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