Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

[m3g4tr0n]

Acer Aspire A114-31 DA0Z8PMB8D0 Rev D Z8P
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connecting to a bench supply and powering on its consuming 0.80amps. nothing gets warm not even the cpu.

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

What is the resistance to ground at the pointed area?
Try to inject 19v ~ 1A in that point and see what is getting hot

[piernov]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

Never randomly inject 19V… You don't even know what state the machine is in.
First take some voltage measurements on all the large inductors.

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

Never randomly inject 19V… You don't even know what state the machine is in.
First take some voltage measurements on all the large inductors.

I didn't say to test here and there randomly. I pointed out specific place and this is 19v power rail, coming there with 1A given that 0.80amps consumption is already indicated in bench supply, witch (most probably) indicates short to ground somewhere shouldn't be a problem, but yes in theory if there is a shorted upper mosfet somewhere in one of the switching power supplies, it might be dangerous, so I said to measure the resistance to ground first. And also it's a good idea to measure the resistance between +19v and all coils. If somewhere the resistance is low the upper fet is shorted.

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

voltages attached
1. dc connected / 2. powered on


resistance between +19v and all coils showing OL using ohm range using M ohm range getting some values 0.44x on all coils apart from one thats 2.2xx left side of battery connector.

injected +19V still taking 0.80amps

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

double post

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

What is the resistance to ground at the pointed area?

I didn't get the value?

Also measure voltage drop to ground on all coils.
Measure voltage drop to +19v power rail on all coils.

Use diode mode (voltage drop) on multimeter for all measurements.

P.S. Just to let you know OL means "overload" as the reading is higher than the meter can display.
P.S2 3.3v on bios chip pin number 8 and power button present or not?

[SMDFlea]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

voltages attached
1. dc connected / 2. powered on


resistance between +19v and all coils showing OL using ohm range using M ohm range getting some values 0.44x on all coils apart from one thats 2.2xx left side of battery connector.

injected +19V still taking 0.80amps

Measure resistance with no power atached .

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

I didn't get the value?

Also measure voltage drop to ground on all coils.
Measure voltage drop to +19v power rail on all coils.

Use diode mode (voltage drop) on multimeter for all measurements.

P.S. Just to let you know OL means "overload" as the reading is higher than the meter can display.
P.S2 3.3v on bios chip pin number 8 and power button present or not?

Diode mode:

value arrowed:
0.482

coils / ground - red ground / black coils
1 - 0.392
2 - 0.221
3 - 0.392
4 - 0.101
5 - 0.131
6 - 0.544
7 - 0.181


coils / 19v - red +19 - black coils
1 - 0L
2 - 0.792
3 - 1.703
4 - 0.687
5 - 0.689
6 - 0L
7 - 0.926


bios W25Q64FWSIQ
pin 8 - 1.78v

power switch
3.3v

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

Measure resistance with no power atached .

resistance to ground with no power. did you also want resistance values from +19v rail?

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

OK good job, so far so good...
I can't see obvious fault or problem according to your measurements, except the strange 0.8A drown from the bench supply, if you are sure that there is no hot areas of the board (including processor and ITE chip), the next step is to make sure bios chip is ok. I assume you don't have a oscilloscope in possession, so the only option without the oscilloscope to see that there is bios activity when you press power button, is to solder a LED to to pin 2 an 4 of the bios chip (check the attached picture). So solder the LED as in the picture, connect the charger and press the power button, if there is bios activity the LED should flash for a few seconds, if the led is not flashing it mean there is no data exchange, and the next step is to reflash the chip with the known good bios image.

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

OK good job, so far so good...
I can't see obvious fault or problem according to your measurements, except the strange 0.8A drown from the bench supply, if you are sure that there is no hot areas of the board (including processor and ITE chip), the next step is to make sure bios chip is ok. I assume you don't have a oscilloscope in possession, so the only option without the oscilloscope to see that there is bios activity when you press power button, is to solder a LED to to pin 2 an 4 of the bios chip (check the attached picture). So solder the LED as in the picture, connect the charger and press the power button, if there is bios activity the LED should flash for a few seconds, if the led is not flashing it mean there is no data exchange, and the next step is to reflash the chip with the known good bios image.

just tried that led method, but the led just stays lit dimly. no flashing and the board is consuming 0.94a now.

thanks for your help so far.

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

just tried that led method, but the led just stays lit dimly. no flashing and the board is consuming 0.94a now.

thanks for your help so far.

I think it's time to flash the bios with a known good dump, backup your bios just in case and reflash with a new one. No flashing mean no data exchange, so probably the bios is corrupted.

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

tried 2 dumps so far from the thread search you linked. still the same, i'll try more tomorrow.

something is getting warm just a little not sure what.

circled area is page 27 on schematic. big chips 6414 and 6752

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

tried 2 dumps so far from the thread search you linked. still the same, i'll try more tomorrow.

something is getting warm just a little not sure what.

circled area is page 27 on schematic. big chips 6414 and 6752

There is nearly 1A consumption, something should be hot, and you must find it.
6414 and 6752 are cpu vcore power supply fets. Are you sure the cpu is cold? Clean the termal paste and find out. It's very strange - cpu power supply to be hot and the cpu to be cold, something is not ok. Check the black 330 tantalum capacitor on the back side, or even better replace it.

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

There is nearly 1A consumption, something should be hot, and you must find it.
6414 and 6752 are cpu vcore power supply fets. Are you sure the cpu is cold? Clean the termal paste and find out. It's very strange - cpu power supply to be hot and the cpu to be cold, something is not ok. Check the black 330 tantalum capacitor on the back side, or even better replace it.

removed the 330 cap, amp draw was still the same. took of the right fet still same then took of the chip underneath PU4 and now something is taking the amps i think the other fet. voltage drops to 4.67v and taking the whole 1amp i set.

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

removed the 330 cap, amp draw was still the same. took of the right fet still same then took of the chip underneath PU4 and now something is taking the amps i think the other fet. voltage drops to 4.67v and taking the whole 1amp i set.

No no no, please don't do it this way, this is not working like that, I told you to check or replace the cap, not to remove it and then power up the board! We want to repair the machine not to kill it, you can't randomly remove the parts from the board and then connect the charger!!!

[m3g4tr0n]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

@Vesko356, thanks for all your help. ordered the tantalum caps on friday but laptop owner (cousin) decided to get new better spec laptop and sell this for spares.

thanks again for your help.

[Vesko356]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

@Vesko356, thanks for all your help. ordered the tantalum caps on friday but laptop owner (cousin) decided to get new better spec laptop and sell this for spares.

thanks again for your help.

You are welcome.

[kalilinux25]

Re: Acer Aspire A114-31 DA0Z8PMB8D0 Z8P Not powering on

@Vesko356, thanks for all your help. ordered the tantalum caps on friday but laptop owner (cousin) decided to get new better spec laptop and sell this for spares.

thanks again for your help.

was the fixed with caps?