Acer nitro 5 an515-55 dead

[Mailf]

Hello i have acer nitro 5
AN515-55
Fh51m la-j871p
rev: 1b

Does nothing at all, no bootup, no power ligts, no charging lights nothing.
It just suddenly died

My batter was always good, now reading 0volts
I have no power on de dc jack, when i plug in the charger the charger turns off..

How can i test if the dc jack is bad and the rest wil work ?

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of the DC power jack. Post clear pics of this connector for a review. After this jack will be the DCin mosfets. Measure if they are shorted to ground. If yes, suggest to remove the first DCin mosfet off the board. Then test if the DC power jack remains shorted or not. If yes, the jack is most likely defective. Have not yet reviewed the schematics but this is a general guideline.

[Mailf]

I tried another adapter that does not go in safe mode from another laptop this gives 0.4-0.9 v on the dc jack and the first mosfets.

This is the jack.

I have allot of other cabled dc jacks, is it possible to solder the red and black wire to the board to test out if the problem is the dc jack ?

Dont know where to solder it on ?
This jack has so many pins

[rogfanther]

No. If you solder past the jack, without removing it, the short will still be there, and my affect your reading.

Measure the resistance to GND of the jack and mosfets, and post the results here.

[Mailf]

All these things get hot circled, second mosfet most... (Image)

first mosfet 1 probe to ground all pins 500 ohm range

2nd mosfet 500 range input side other side all 4 pins 003

What does this say?

[mcplslg123]

Not the proper way to measure a mosfet.
Set your meter to atlest 200K or more scale.
Put black probe on pin1 and then measure resistance between
PIN1 to pin4
Pin1 to pin8
Pin4 to pin 5

Repeat it for both dc-in mosfets.

However, i strongly feel your main rail is shorted. Confirm that by measuring resistance to GND on CLR located just after the dc -in mosfet.

[Mailf]

Yes seems my main rail is shorted. the clr is 0.00 on 200k mode, or 0.004 in diode mode without beeping mode....

And most inductors are also 0.00 ground on 200k ohmse, and 0.004 to 0.009 in diode mode (it changes every time)



All red is 0.00 on 200k ohm mode

[alfredposadas09]

Yes seems my main rail is shorted. the clr is 0.00 on 200k mode, or 0.004 in diode mode without beeping mode....

And most inductors are also 0.00 ground on 200k ohmse, and 0.004 to 0.009 in diode mode (it changes every time)



All red is 0.00 on 200k ohm mode

dont focus too much on those coils they are very common that the reading is very low

[alfredposadas09]

dont focus too much on those coils they are very common that the reading is very low

what is the resistance on the PRB3?

[Mailf]

Prb3 is that clr ? 005 in diode mode

[Mailf]

About the mosfets i dont know what 1 to 8 is ?

this is the mosfet reading in 20k mode

0.05 and the other 0.06

Isnt that way to low ?

[alfredposadas09]

go to pub1 and give me reading of these pins voltage and ohms
pin 28
pin 6
pin 24
pin 5

[Mailf]

Where starts pin 1 on pub 1 ? i dont have any schematic of this pub1 and cant find one either.

The voltage with the non original adapter that does not ahuts off does not get higher than 0.4 to 0.9 v from the powerjack and the first mosfets, so is the voltage important then on pub1?

First of all all thanks for your help.

[mon2]

See section 5 (top view) here:

https://www.ti.com/lit/ds/symlink/bq...lsrc%253Daw.ds

[Mailf]

Thank you i first need smaller probes...

For the first mosfet is it normal to have pin 1 (with dot) connected to all other pins on other side ? 001 in diode mode

Theres only resistance between the dot and gate 005

[mon2]

Use only resistance mode. What is the resistance in ohms? 5 ohms? Definitely shorted. Each resistance check should be hundreds of k ohms or higher if the part is not defective. Seek out a replacement. They are cheap and commonly found on most motherboards. Share the topside markings of this and also the replacement parts for a quick review. BQ chargers will often use N-channel 30v rated mosfets (5x6 size). No power to the board (only to the people) when using resistance or diode mode checks.

[Mailf]

Yes in diode mode source to gate 005
Source (dot) to drain all 000

[mon2]

Diode mode testing is different than resistance mode testing. The shared diode mode measurements make it clear that this part is defective.

[Mailf]

Thanks, I tried to remove the mosfet but that didnt work with solder iron so i need to buy hot air station. It melted a little but now my ac adapter doesnt go into protection mode anymore

For the first time ill get 19v on the dc jack and the mosfet, however only 0.5v on the other side.

So need to wait for my hot air station first...
Does this means the short is gone? And now the mosfet is just broken or something ?

[mon2]

Yes, you will definitely require hot air tools + tweezers + flux. This combination of tools will then melt the solder that is under this mosfet (including the belly side solder). Only then can the tweezers pluck the part of the board properly. Be sure to watch YT videos on the topic and be patient. Test on donor boards before removing this part. Too much heat will burn the board. Too little heat will not allow for the removal nor soldering. To high air pressure will send the nearby SMD parts into the next dimension. Each parameter must be balanced.

Also, be care to not tear the PCB pads and traces off the circuit board. The mosfets are inexpensive and usually ~1 USD each. You may even have suitable mosfets on a donor board.