ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

[inflex]

Nothing showing on screen. Tried VGA too. Swapped RAM, same issue.

All rails are showing up that I can determine, including ALL_SYSTEM_PWRGD, and H_DRAM_PWRGD, +VGFX_CORE and H_CPUPWRGD.

Main concern is that PSL8103+12VSUS is 13.5V, and PL8100+3V0 is 3.27V

Plugged in USB hub, +5V shows up, then device detected in the hub shows up, but due to lack of POST there's no blinking activity as sticks are checked for boot.

Any further suggestions?

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

bump.

Wondering if perhaps I'm not getting an RTC clock or BIOS clock.

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

I'm interesting in your issue, what's revision number ?

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

Thank you Jasko, I have gone through that repair guide to test everything.

The only voltage not present is PJP8700 +0.8VSO, the whole area is a no-stuff.

It's an X401A REV 2.0 board.

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

Attached is the PJP8700 area to show what I mean by "no stuff".

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

PJP8700 is open by default, I assume is not in use in this configuration.
If the board power on, on pin 2 PJP8700 +VCCSA = +VTT_CPU you should have the +VTT_CPU voltage,
without this voltage, even if there is the 0.8VS on pin 7 (check) for PU8700 = pin 4 PQ8700, will not be present on pin 1 of PJP8700. However, I would check the PU8200 if +VTT_CPU
is not present, if is present check PU8700 but If I see well on the photo this ic is not in place, if so this confirm the absence of the 0.8VS

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

You confirm that this boardview is correct ?

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

+VCCSA is the "system agent voltage" but I don't know which is the default voltage, if the boardview I have is correct, seems to be = +VTT_CPU. When the PJP8700 is on, the PJP8701 must be off and viceversa. I find this arcticle
http://www.overclock.net/t/1519310/w...io-actually-do

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

You confirm that this boardview is correct ?

Many thanks for the boardview, that's actually going to make things significantly easier. Don't suppose you know where I can get the schem as well?

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

The schematic is not available, I tried with no luck

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

It certainly has me stumped for now. If I insert a new USB stick while it's on, it'll 'check' it (USB stick activity light goes on), so not sure what state this laptop is being held in. Screen backlight is on. HDMI, VGA go in to sleep mode. Connected the keyboard back up to try press the screen-change button, no avail.

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

I just noticed something interesting.... I do not get an AC-IN light, that is, if I plug in the AC and nothing else (no battery), there's no indication that it's plugged in (but if you put a battery in, it'll show the charge orange light )

[jasko_jacker]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

with a debug card you can try to use jdebug port but if all signals are present
only remain (gpu is inside cpu):
1 - IT8517E
2 - BIOS (I believe that you have already tried it )
3 - PCH (on a G75VW with the same issue I solve by changing it)

[khaahk]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

try bios?

[inflex]

Re: ASUS X401 board (X501), no POST, ALL_SYSTEM_PWRGD present too

Thanks, I'll order a replacement BIOS and see if that helps. Have a bad suspicion it might be the PCH, in which case this laptop will become a donor for parts.