Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

[malogro]

Hello all,

I'm stumped on this guy, so wanted to see if anyone has any further ideas:

Intro:

This is an Acer Nitro 5 AN515-55-55M1 with unknown prior history (bought "as-is" on eBay). It charges the battery and powers on from both AC adapter and battery, so I think this rules out main power issues.

Upon attempt to boot, it will "reboot" (meaning powers down and then powers on again) only once, and then stays stuck in a status of lights on / no post / no monitor. Powering on with fn+esc maxes out the fans on first boot attempt, but once it powers down and on again (on its own), fans go back to normal despite holding fn+esc.

All peripherals were tested in another laptop and are known good (keyboard / LCD / RAM / battery / AC adapter).

Edit because I forgot: Visual inspection shows nothing, board appears brand new.

Testing:

I began by testing the main power rails:

19_IN: There and good (19V with adapter)
5VALW: There and good (5V)
3VALW: There and good (3.3V)
1.8VS: There and good (1.8V)
1.2V_VDDQ: There and good (1.2V)

EC_RSMRST#: There and good (3.3V) <- I'm assuming that's correct

PCH_PWROK: There and good (3.3V)
SYS_PWROK: There and good (3.3V) <- That one puzzles me.

The main suspect:

Upon testing VCC_CORE and VCC_GT (cooler off), VCC_GT is there (0.8V or thereabouts), but VCC_CORE is not. I recall measuring around 1.8V on good laptops (measured on PUH2-5), or at least something. Does not appear to be a short either, as resistance to ground measures ~20ohms. CPU does get hot, so that's weird to me as well.

I have no idea what to use to debug further. Schematic shows PUH2-5 are responsible for that VCC_CORE (I think?).

My next step was to replace PUZ1 from a donor board (I think that's the CPU VCC_CORE controller), but I stopped myself since I do not like to just throw parts at a problem. Is there anything else I can do to debug why that voltage isn't coming on? My only other idea is BIOS issue...

Thank you!

[kalilinux25]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Hello all,

I'm stumped on this guy, so wanted to see if anyone has any further ideas:

Intro:

This is an Acer Nitro 5 AN515-55-55M1 with unknown prior history (bought "as-is" on eBay). It charges the battery and powers on from both AC adapter and battery, so I think this rules out main power issues.

Upon attempt to boot, it will "reboot" (meaning powers down and then powers on again) only once, and then stays stuck in a status of lights on / no post / no monitor. Powering on with fn+esc maxes out the fans on first boot attempt, but once it powers down and on again (on its own), fans go back to normal despite holding fn+esc.

All peripherals were tested in another laptop and are known good (keyboard / LCD / RAM / battery / AC adapter).

Edit because I forgot: Visual inspection shows nothing, board appears brand new.

Testing:

I began by testing the main power rails:

19_IN: There and good (19V with adapter)
5VALW: There and good (5V)
3VALW: There and good (3.3V)
1.8VS: There and good (1.8V)
1.2V_VDDQ: There and good (1.2V)

EC_RSMRST#: There and good (3.3V) <- I'm assuming that's correct

PCH_PWROK: There and good (3.3V)
SYS_PWROK: There and good (3.3V) <- That one puzzles me.

The main suspect:

Upon testing VCC_CORE and VCC_GT (cooler off), VCC_GT is there (0.8V or thereabouts), but VCC_CORE is not. I recall measuring around 1.8V on good laptops (measured on PUH2-5), or at least something. Does not appear to be a short either, as resistance to ground measures ~20ohms. CPU does get hot, so that's weird to me as well.

I have no idea what to use to debug further. Schematic shows PUH2-5 are responsible for that VCC_CORE (I think?).

My next step was to replace PUZ1 from a donor board (I think that's the CPU VCC_CORE controller), but I stopped myself since I do not like to just throw parts at a problem. Is there anything else I can do to debug why that voltage isn't coming on? My only other idea is BIOS issue...

Thank you!

Wait for other comments but , try to request a new clean me bios of your board on the BIOS request section maybe that will help.just a suggestion

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Thanks! Yeah may want to try that as well, but need to get a flasher first...

[kalilinux25]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Thanks! Yeah may want to try that as well, but need to get a flasher first...

also please always have a complete details of your board and drop the schematic here.

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Ah, yes. It's a GH51G LA-L181P Rev 1A.

https://www.badcaps.net/forum/showthread.php?t=110980

[mcplslg123]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

+VCC_SA present?

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

I'm assuming it's the one measured at PLG101. If so, yes, present at 1.8V.

EDIT: Sorry, never mind, schematic actually says PLA1. Trying to locate it now...

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Couldn't quite find VCC_SA. Closest I could find was VCC_AUX, which is the one on PLG101, which is present at 1.8V. If that's not the one, would you point me towards where I can find that signal?

[Stevedb]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Does the capslock toggle on external keyboard. That is sign that the board is posting if not i would go for cleaning first your original bios.

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

It does not light up on external or embedded keyboard. I will get ahold of a flasher and try reflashing the BIOS.

[mcplslg123]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Yes, strange.Schematic does mention VCCIO/VCC_SA but doesnt lead anywhere.

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Update: BIOS was reflashed to ME clean. Same exact symptoms.

It DOES write to BIOS (I read back from it to see if it had changed), which I think is a good sign. But still no POST (CAPS LOCK test still negative).

My next idea would be to go for broke and replace PUZ1 or inject ~1.8V directly to VCC_CORE to see if any signs of life, but suggestions are appreciated.

[mcplslg123]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Dont play with voltage injection without finding the fault. AFAIK,VCC core should be approx 1V on this platform.

[piernov]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Upon testing VCC_CORE and VCC_GT (cooler off), VCC_GT is there (0.8V or thereabouts)

I'm a bit confused here since VCC_GT should not exist on this platform. Ice Lake/Tiger Lake has FIVR so single rail (VCCIN) from motherboard to CPU for all the core logic including CPU VCore and iGPU VCore, and another rail (VCCIN_AUX) for the auxiliary logic. Some other rails also feed the CPU for memory, I/O and standby operation.
According to Intel's datasheet, VCCIN_AUX should be 1.8V.
VCCIN is not specified since it's controlled by SVID but I'd guess it's a bit higher that the usual VCore, maybe similar to Haswell/Broadwell.
As usual though, VCCIN will be absent if CPU auxiliary circuits do not initialize and there is no SVID communication.

[malogro]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Ah, ok, let me clarify. What I mentioned as VCC_GT is actually the graphics card core (NVVDD), so my bad there.

So VCCIN is missing, because something is not initializing correctly then. Is there any sort of checklist I can go through to see what is failing?

[eenee]

Re: Acer Nitro 5 AN515-55-55M1 [GH51G mb] powers on, no vcc_core

Ah, ok, let me clarify. What I mentioned as VCC_GT is actually the graphics card core (NVVDD), so my bad there.

So VCCIN is missing, because something is not initializing correctly then. Is there any sort of checklist I can go through to see what is failing?

Have you found a solution for this motherboard? I seem to have the same symptoms as yours.

[malogro]

Following up as I just saw I never did. The issue on that motherboard was the PCH. Once I lifted the PCH, there were several traces that were ripped. As said, some aux circuits have to properly initialize and they weren't.

Replacing the PCH / traces should do the trick.