Acer Nitro LA-501P-dead

[luckydip]

Working on a Acer Nitro LA-501P. On attaching a charger there is a blinking light on the charger - laptop dead. Took it apart and there is low resistance between (pin 1&5) PQ 11 and pin 5 and ground PQ10. I have marked this on the attached image.

I injected 1.5v on pin 5 PQ10 and there is a draw of upto 1.5A, the only thing that heats up is right side of CPU (+VCC_GT). Its warm to touch but not blistering hot.

Is it worth loking at the PQG1 area or is this a dead CPU or any other areas I should look at?

thanks

[mon2]

Re: Acer Nitro LA-501P-dead

hi.

1) with the adapter connected, what is the DC voltage reading:

a) for pin 5 on Q11 ?

b) for pin 5 on Q10 ?

2) if possible, remove PQ11 & PQ10 off the logic board and test the resistance between source & drain for each for a possible short condition.

Do not power on the logic board with the parts off.

[luckydip]

Re: Acer Nitro LA-501P-dead

Hi

thanks for your reply.

Sorry I uploaded the incorrect screenshot and started the confusion with the part numbers - do you want me to check PQB11 & PQB12 (new screenshot attached?) The resistance readings from the first screenshoot are the same.

a) for pin 5 on PQB11 ? 400mv-1000mv constantly changing

b) for pin 5 on PQB12 ? 0-100mv constantly changing

2) if possible, remove PQ11 & PQ10 off the logic board and test the resistance between source & drain for each for a possible short condition.

Resistance between source and drain:
PQB11 - 5.5Mohms
PQB12 - 6Mohms

If these aren't the correct readings then please let me know.

thanks

[mon2]

Re: Acer Nitro LA-501P-dead

a) for pin 5 on PQB11 ? 400mv-1000mv constantly changing

Your 19vdc from the external power adapter is not reaching this part of the logic board or is shorting.

Measure the external power adapter voltage @ PJP101 connector. This is the first entry of the power adapter into the system.

Check @ pins 1, 2 or 3 of PJP101 (red probe of your meter) & black probe of your meter to ground).

You should see 19VDC (approx) here. If not, your external power adapter is not working or is being shorted by this logic board.

If no voltage is read, disconnect the power adapter and power cycle the AC cable for your adapter (in an attempt to remove any short condition inside the adapter). Then check the voltage directly on the power adapter - center pin should be @ +19VDC and the outside barrel will be ground.

Do you see about 19VDC on the power adapter ?

[luckydip]

Re: Acer Nitro LA-501P-dead

19V not present at PJP101

checked adaptor only on barrel, 19v ok
checked output of jack charging lead without it connected to motherboard 19v

Looks like a short on the board?

[mon2]

Re: Acer Nitro LA-501P-dead

Yes. Do you have hot air soldering tools? Review the above sticky posts from @Piernov on possible issues with the first stage power supply circuits. Recently had a fault on a HP that was due to the first mosfet being shorted across source and drain.

Any liquid damage on the logic board or just died one day?

You should remove all power and check resistance to ground on every inductor (often grey parts). Checking for very low resistance to ground which is often due to a shorted capacitor. Then the local power rail will shutdown to prevent damage.


https://www.badcaps.net/forum/showthread.php?t=90356

[luckydip]

Re: Acer Nitro LA-501P-dead

No liquid damage on board. When adaptor is connected both of the fets are very hot.

I do have hot air and will take a look at the stickies. Do you think I should order in both fets?

[luckydip]

Re: Acer Nitro LA-501P-dead

Followed my initial theory and removed PQG1 - short to ground on pin 5 PQB12 gone. Is it worth changing PQG1 and continuing with this repair or has the CPU been damaged?

thanks

[Th3_uN1Qu3]

Re: Acer Nitro LA-501P-dead

Shorted CPU, replacement motherboard time... ��

[luckydip]

Re: Acer Nitro LA-501P-dead

Shorted CPU, replacement motherboard time... ��

thanks