Acer Nitro 5 randomly doesn't power on (but charge light is on)

[liquidzorch]

Hello. I have an Acer Nitro 5 AN515-44-R58M here that randomly will not power on. It can be good for some days, then all of a sudden it will not power on, the battery charge light will be on, but no signs of power. To get it to power on, sometimes what will work is disconnecting and reconnecting the battery, but it doesn't always work.

It is hard to diagnose since I can't reproduce the issue (get it to not turn on). Right now it powers on, so I probably won't find any missing voltages, but it's been doing this for months, where you press the power button and nothing happens, even if you hold it down for 30 seconds and try again, nothing happens.

There has been no obvious signs of damage (no liquid, no falls, no opening the case before this started), and it's a pretty new laptop.

Is there any way I can go about diagnosing this issue, normally I would look for missing voltages, but it's kind of hard to find an issue on a working laptop? Maybe someone already had this same issue once?

Thanks in advance!

[Stevedb]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

On the battery does it power up. I would first do health check on all the coils to see which power supply doesn't power up. First make a hd picture from your bozrd with all the voltages on coils and resistance too without any power. Also check the first and second mosfet for internal short.
I would start with those measurements.

[liquidzorch]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

When it fails, it will not power up on only battery nor with charger connected. I did get to test some coils when it was failing, and the only voltage that was present when off was 5v, which according to the schematic, is correct, 5vALW is the only voltage that is present when off and charger connected (besides the battery and charger voltage of course).

RTC power should always be present, but I have not been able to check it since now the laptop has not failed to power on again... I am waiting for it to fail to continue testing everything, as I doubt I will find a fault while it is actually working.

[mcplslg123]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

Is the power switch is in keyboard itself? Visual inspection under microscope/magnifying glass done?

[liquidzorch]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

Yes, the power switch is in the keyboard. I have visually inspected the board quickly with a magnifying glass, I see no noticable damage.

[liquidzorch]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

The bad thing is, my friend (the owner of the laptop) says it can go for days or even weeks without failing, but all of a sudden it will just stop powering on. The charge light will come on if connected, but no power when power button is pressed.

When he brought it to me, it was in this state, I couldn't turn it on, I even tried pressing the power button hard, and for over 30 seconds, nothing happened. I opened it up unplugged the battery and re plugged it, and it worked for one boot up. Then I shut it off, it wouldn't start back up, so I started probing, testing for voltages, and then all of a sudden it turned back on (without disconnecting the battery) and hasn't failed since.

[mcplslg123]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

Very very likely,your keyboard is faulty(power button part of it). disconnect the keyboard cable from motherboard and try turning it on by shorting power button pin of kbd connector to GND.

[liquidzorch]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

I waited until the laptop wouldn't power on, the day it wouldn't, I flipped it over and probed the power button (pin 1 keyboard connector), and while pressing the power button it would go down, but only to 1.4v. So I shorted pin 1 to gnd and it powered on. So it is the power button.

After doing that, it has once again started to work normally (the power button does lower the button rail to 0v when pressed). So my new question, why? Checking resistance to gnd when pressed, I get 140ohms on pin 1 (when working). Now that it's working, I can't measure how much resistance there is when it fails. So I'm wondering if it's just a bad connection at the motherboard, or if the keyboard is faulty. I'm guessing a bad connection since it works most of the time, but I could be wrong.

[mon2]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

The contacts of the switch / membrane being pressed are not clean. If visible, consider to use IPA to clean the switch but alcohol and rubber do not mix. Try to clean the contacts only.

This case sounds familiar from a few years ago. In the end, suggested the tech apply a resistor in parallel to this on/off switch to assist in reducing the resistance. It worked after some trial & error of different resistor values.

[liquidzorch]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

Thanks, I'll see if I can clean it. It would be so much easier if it would always be failing, that way I know if what I have done to it has fixed it.

[mcplslg123]

Re: Acer Nitro 5 randomly doesn't power on (but charge light is on)

This is a cery commom fault with keyboards with power switch across all brands. Just replace the keyboard.