Acer Nitro AN515-55-51QY, won't turn on, no charge

[Glxio]

Hello, I introduced myself on the forum and followed the rules. I own an Acer Nitro 5, model AN515-55-51QY, which has completely broken down. When I open NitroSense, it shut down entirely. I can’t turn on the PC with or without the charger—it makes no difference. No lights appear. I tested the DC IN port to connect the charger and measured 0.533V on my multimeter. Normally we need to find 19v on PJP101 DC-IN connector, right ? I’ve done quite a few tests on the capacitors; only PRB49 shows 0.000 ohm, which I believe is faulty. I can’t measure PQB11 and PQB12 because boardview don't show drain or source . Please I need help finding the cause of the failure.

Motherboard model : G51HM LA-K862P Rev1.0

Thank you so much

[mon2]

Confirm if the power adapter is able to supply the original ~19v to the board. Perhaps the power adapter is faulty?

Remove all power. Meter in resistance mode.

Measure the resistance to ground of the following:

PL101
PQB4 ; pins 5-6-7-8 (any of these are ok)

Post each resistance measurement.

[Glxio]

The power supply provided 19.70v, and work on an other laptop

PL101 has 6k ohm and 0.53v also like the DC-IN jack

PQB4 not found on my motherboard, and not found on my boardview file

[Glxio]

I also add that the capacitor PRB3 and PRB46 are no longer present, probably HS

[mon2]

PL101 has 6k ohm and 0.53v also like the DC-IN jack

To confirm, this known good 19v adapter is only providing 0v53 when measured @ PL101 to ground?

Confirm your DCin connector is ok. Check the soldering. Check if the center pin is mating with the power adapter ok or not. If there is no short @ PL101 to ground, then this adapter voltage should at least reach PQB11.

Share the voltage to ground of ADAPDET. Also check ACDET.

PRB49 shows 0.000 ohm

This is the proper resistance. The part value is marked in the schematic as 0_0402_5% = 0R ohms; 0402 SMD code body size; 5% tolerance for the resistance value. So @ 0R ohms, this is accurate.

[Glxio]

So, when I test the charger just plugged into the wall, I get 19.70v. Then, when I connect it to the PC and test PL101 to ground, I get exactly 0.53v. Same as PJP101.
I disconnect the charger and test it again, it shows 2.51v, as if the charger went into protection mode. But I can get back the charger in normal value by unplugging and plugging it back in.

I have 2 missing ceramic capacitors, PRB3 and PRB46. PRB49 is also slightly damaged. I’m not going to replace them for now; I mainly want to figure out why I’m getting this voltage drop, especially since my PC suddenly shut down

PQB11 gives me 0.53V, PQB12 as well

What are ADAPDET and ACDET and how I measure them ?

THanks for your help

[mon2]

Test with only the power adapter for now. Disconnect the battery.

Locate the dual diode @ PDB1. Meter in diode mode. Place the red meter probe onto pin #3 of this dual diode; black meter probe onto pin # 1. Meter should conduct.

Reverse the meter probes and the meter should show 'OL' = blocking.

Repeat with pins #2 & # 1 - same results if the diode is ok. We are hunting for the reason why the power adapter is going into protection mode since the there is no short on the incoming power path @ PL101.

Does this dual diode checkout ok?

[Glxio]

The test of PDB1 gives me 0.38v between pins 3 and 1, and in the reverse I get OL.
Between pins 2 and 1, I also get 0.38v, and in the reverse I also get OL.

ACDET gives me 2.62V

[mon2]

ACDET gives me 2.62V

Then you must have the proper power adapter voltage since the ACDET voltage is built by the same power adapter input but lowered using the 2 resistors on this line. The resistors act like a voltage divider. Confirm that you have a proper ground and measuring at the contacts of the parts under test.

Place black meter probe to ground. Red meter probe onto the pin # 3 of the dual diode. You should be able to measure the adapter voltage here. Then move the red probe onto pin #1. The voltage should be slightly lower due to the internal forward voltage drop due to the diode.

[Glxio]

Oh, and I remember when I dessasembly the laptop, some liquid around the 2 mosfets PQB11 and PQB12, also PCZ65 and PCZ47, with a light burn smell, I think probably the 19v rail is the faulty but don't sure, I search how to measure the 2 mosfets exactly with the correct measure

[Glxio]

Ohoh, I have 0.53v on the 3rd pin , and OL on the 1st pin

[mon2]

Measure the voltage to ground of PRB47. One leg must be the adapter voltage. Confirm it.

Then remove all power. Meter in resistance mode. One meter probe on PRB47 where you measure the adapter voltage; other meter probe on PL101. This resistance should be ~0R ohms since this is the same DCin power rail.

[Glxio]

Is it indeed to the left of PRB47 that I should place my red probe? If it’s on the left, I get 0.53v, but if I put it on the right, I find 2.81v.
When I do the resistance test, placing the red probe to the left of PRB47, I get 0.

[mon2]

You cannot measure resistance if the board is being powered. Resistance and diode mode checking is always without power to the board.

Test both sides of 19V_VIN. The high side should be the adapter voltage. This same voltage should be present on PL101.

[Glxio]

If I understand correctly, I need to test each 19V_VIN and the measurement should be the same everywhere? And this voltage should also be the same on PL101?
According to the schematic, I should test by placing the black probe on GND, and the red probe on the third pin for the 19V_VIN of PDB1, and on the side marked “1” for PRB44 and PRB47 ?

[mon2]

Yes, missed the PRB47 reference above. Suspecting that you have a broken trace somewhere since you do have a valid ACDET voltage but not elsewhere.

Start with the PRB47. Confirm that you have ~19v to ground on one of the 2 pins on this thermister PRB47. Once this is confirmed, test the other places where the same voltage should travel including the dual diode and the PL101 ferrite bead.

[Glxio]

Okay, I’ll do the tests tomorrow, but what happens if I find 19V, or if I don’t find 19V on any of them? Where would the problem be located? That way I can learn from you

[mon2]

These same labels are the same pcb trace unless there is a broken one in the path. After double checking each point, you may have to solder a piece of wire to complete any broken connections. First confirm that the adapter voltage is indeed present somewhere on the board. Test again pl101 - both sides.

[Glxio]

I just finished the tests. Each 19V_VIN point gives me 0.53V, which is the voltage coming from the charging port.
I’m also attaching photos of the PQB11 area, as well as the PL103/PR102 area, where it looks like the capacitors may have melted. Since PL103 is also a 19V_VIN point to measure, it also gives me 0.53V.
Only the two MOSFETs, PQB11 and PQB12, need to be measured. On which pins should I place the multimeter probes to test drain/source/gate? I have serious doubts about this.

[mon2]

PL103 area has a lot of flux. Apply IPA (alcohol) with a cotton swab / Q-tip to clean up this region.

Flux and remove PL103. This will isolate the power adapter DCin power path and the main board.

Insert the power adapter and test again. Do you see the full adapter voltage on the PCB pad @ PL103? Red meter probe on the PL103 pcb pad; black to ground. Test both PCB pads to locate the proper one that mates to the adapter connector. You must see ~19v here otherwise the DCin connector is defective.