ASUS G14 GA401QE Wont Boot

[mikoolbil51]

I'm looking for some advice on this laptop. As stated, this is a GA401QE and the issue it has is that it will not boot. Laptop powers up as soon as the charger is plugged in, the keyboard backlight lights up, the activity LEDs come on, but then 15 seconds or so later, it shuts down and restarts. It will continue to do this for as long as it is plugged in. Would anyone here have seen this before? I'm thinking maybe a faulty BIOS, but I'm not 100% sure and wanted to get some feedback. Thanks.

[mon2]

Are you using the official and recommended power adapter for this unit? This is a gaming laptop so is a pig on current consumption. Be sure the power adapter is at least 180W rated or higher.

[mikoolbil51]

Thanks for the reply. I'm definitely using the included power adapter (240W), but I did try a different one to rule it out and got the same result.

[mcplslg123]

If the mb restarts after 10-15 secs.then there is missing rail.
Start checking voltage at coils.

[ResoluteHawk]

Check resistance AND voltage for all power rails. You could have a power rail with a lower than normal resistance that is being dragged down by a faulty mosfet that is leaking voltage.

On these G14's, your resistance values on all primary and secondary power rails (19V, 5V, 3.3V, 1.8V) should be in the kOhms with the exception of the memory (1.2V) coil which should be around 100-250 Ohms depending on which brand of RAM you have.

Also if the laptop is restarting every 10-15 seconds, I'd also have a look at the resistance of the CPU VCORE coils. They should be 4-8 Ohms. If these measure any lower than 2-3 Ohms, a component on CPU VCORE has an issue. These numbers are from my experience working on G14 boards.

If the resistance of the CPU VCORE coils is good, make sure that voltage is actually going through them.

Your CPU PWM IC could also be defective, causing a power on restart cycle.

Is the CPU getting warm?

[mikoolbil51]

Thanks again for the advice. I measured resistances and also voltages at each respective voltage rail coil, I.E. (19V, 5V, 3.3V, 1.8V and 1.2V) also measured VCORE voltage at 0.7V. This is all while the laptop is in the power on phase of this power cycle issue. These rails are all present when it is trying to power up, however, they all go away when it cycles off (no surprise) with the exception of the 19V which remains at all times as long as its plugged in. CPU does get warm if left to cycle on and off for a period of time. Resistances on each respective rail also measure iaw the above values as you indicated. Im going to try to find a boardview or something to better try and understand the boot up sequence to see if anything jumps out as a potential culprit. Maybe a defective super IO (ITE chip), not totally sure.

[mikoolbil51]

The other thing I cant understand is why it attempts to power up/power cycle as soon as the charger is plugged in.

[ResoluteHawk]

The other thing I cant understand is why it attempts to power up/power cycle as soon as the charger is plugged in.

That's just the way that the EC and lid sensor is designed. All G14's that I've worked on do this as long as the screen is open when you plug it in.

[mikoolbil51]

Good to know. I wasn't aware of that, but helpful know.