Acer AN515-54 won't power on, no leds, no fan spinning, black screen

[madfreak]

Hello, if i could ask You for a help i will be really grateful

I got Acer Nitro laptop AN515-54 dead completely it shows nothing on the screen and no led indicator is on.

The charger is good so it should indicate ( the led on a side of the laptop) that the charger is connected but there is no led present.

The dc connector is also good and the components near by are working fine ( i check but not sure if i done it correctly the voltages )

What i have noticed is that the voltage on the 8PIN of the bios is showing 0V while battery (3V) is disconnected from the motherboard while turning the laptop on. But when that battery ( 3V ) is connected the voltage while turned off is 0V but after pressing on button is showing 3,3V.

Nothing is heating on the motherboard but to be sure i have ordered power supply to inject voltage directly into motherboard

Any help would be really appreciated

Below are the schematics and boardview if someone will need it in future because yesterday i bought them and it is no problem for me to share with others

Thank you really much in advance for help and tips

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Start with the sheet with the charger IC @ PUB1.

Review the first 2 mosfets to see if they are damaged.

Remove the battery but connect the external adapter. Confirm that the adapter voltage enters the first mosfet.

Does this voltage continue to the +19VB label?

Next, remove all power. Meter in resistance mode (2k scale).

Check each of the first 2 mosfets for a short by reviewing the resistance:

Source (1-2-3) & drain (5-6-7-8)
Source (1-2-3) & gate (4)
Gate (4) & drain (5-6-7-8)

Checking for a low resistance reading which means the mosfet is defective and must be replaced.

Then repeat for the 2nd mosfet. Post your readings.

Next, if the mosfets are ok, meter in dc voltage scale of 20v. Carefully measure the voltage on each pin of the charger IC when the adapter is connected.

Post all measurements of the charger IC.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Hi, thank You for reply and suggestion

Maybe that is a stupid qestion ( forgive me please my lack of knowledge )

The first two mosfets are PQB11 nad PQB12 right ?

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Sorry - had one eye open while typing on the phone.

Yes indeed. The first 2 mosfets are often the guilty party to investigate on all products - then move from there.

You will find this to be a 8 legged device (4 pins on each side). Often there is a pin # 1 DOT or marking to denote the orientation.

For the MOSFET and similar looking ICs, you will be counting in a 'U' direction.

So top left = pin # 1 (look for the dot) - or share a clear pic of the part

then next down on the LEFT side = pin # 2

and LEFT side will end in pin # 4 = GATE.

Then right side (BOTTOM) = pin # 5 - DRAIN
pin # 6 (up from this last pin) = DRAIN
pin # 7 = DRAIN
pin # 8 = DRAIN (TOP RIGHT and last pin on the RIGHT)

since many pins are grouped together to support higher current, you can pick any of the common pins to monitor the voltage.

Just post pics if not sure of which pin is which.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

That's it ...nevermind...that chip i guess was ok...before i accidentally touch the 18-19 pin.

2.26v
0v
3.27v
3.27v
0v
0v
0v
0v
0v
0v
3.05v
0v
3.21v
0,.18v
0,18v
1,81v
1v
5,16v 3,08v ( i accidentally short the 18 and 19 pin ) ...
0,06v
0,21v
0,21v
0,36v
0,33v
0,19v
0,4v
1,25v
0,9v
0,91v

...Thread can be closed...f*** that ;(

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Hi. No worries. Keep - carefully, probing the charger IC. You can probe any of the parts that mate with the pins of the charger IC.

If you need to wait, source some nice point probes from Aliexpress which are often ~3 USD for a pair.

It is ok if you shorted those pins, you need to keep posting the details of what is in front of you.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Thank You and i really appreciate Your help. I got a needle probes, so there are tiny and good for that measurment but after i short the pin 17 with 18 the voltage on PIN 18 has dropped from 5,16V into 3,08V and now is even showing 0v. The same has happened with PIN 17 whish was showing 1v and now is 0v.

So i guess firstly i need to replace that IC and then do the next measurments

Ps previously i make a mistake not 18 -19 but 17-18 i shorted

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Yes, the charger IC may need to be replaced. Aliexpress will have these - be sure to source the part with the same markings.

What is the voltage on pin # 18 of the charger IC (PUB1) ?

Would you have access to hot air soldering tools ? Flux & kapton tape are also good to have.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Thank You and i really appreciate Your help. I got a needle probes, so there are tiny and good for that measurment but after i short the pin 17 with 18 the voltage on PIN 18 has dropped from 5,16V into 3,08V and now is even showing 0v. The same has happened with PIN 17 whish was showing 1v and now is 0v.

So i guess firstly i need to replace that IC and then do the next measurments

Ps previously i make a mistake not 18 -19 but 17-18 i shorted

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

ohh well...nothing is happening without a reason and at least someone will have a boardview and schematics if they would need it

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Can i use ISL88739 instead of ISL88739A for that IC ? They both seems the same...

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

I have replaced that IC with ISL88739...and you will not believe...i shorted the same pins again.

LOL... i am sick of it

I will order from alliexpress 10 ic's to be sure that i have spare parts.

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

LOL Have done something similar - replaced the ISL9239 WLCSP tiny bugger like 3 times before realizing that the ISL9239 is NOT the fault. They will end up in my reballing-to-do pile of parts. Stencil is in transit for the ISL9239 / ISL9240 devices.

It was the linked SMBUS lines that caused the battery condition to be not detected properly. The ESD diodes on the line were shorted.

We have all been there. Good idea on ordering some spares.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

I have double checked which PINS i shorted before...and the first guess was the right one ...18-19 same as now

The masurments was :

with ISL88739A before the short

1 - 2.26v
2- 0v
3 - 3.27v
4 - 3.27v
5 - 0v
6 - 0v
7 - 0v
8 -0v
9 - 0v
10 - 0v
11 - 3.05v
12 - 0v
13 - 3.21v
14 - 0,18v
15 - 0,18v
16 - 1,81v
17 - 1v
18 - 5,16v 3,08v ( i accidentally short the 18 and 19 pin ) ...
19 - 0,06v
20 - 0,21v
21 - 0,21v
22 - 0,36v
23 - 0,33v
24 - 0,19v
25 - 0,4v
26 - 1,25v
27 - 0,9v
28 - 0,91v
...
...
...


and with ISL88739 before the short the same measurments were a bit different

1 - 2.2V
2 - 0V
3 - 3.28V
4 - 3.28V
5 - 0V
6 - 0V
7 - 0V
8 - 0V
9 - 0V
10 - 0V
11 - 3,11V
12 - 0V
13 - 3,21V
14 - 0,15V
15 - 0,15V
16 - 1,84V
17 - 1V
18 - 19,5v before short ...2,20v after
19 - 2, something v

i do not want to measure the rest

I have ordered 10 pieces of the same with an A letter IC's (ISL88739A) and additionally i have ordered that part: SY8288RAC...because there are short on caps connected to that chip and maybe this is the fault of no LED-s

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Finally ic's arrived but of course the masurments are a bit different than the previous ones ( there is missing 3,27V on pin 3 and 4 on PUB1)


After replacing PUB1 to a new one ISL88739A and new PU1101 i got those masurments:

[B] PQB11[/B] : 
S : 19.55V 
G: 4.66V 
D: 3,26V

[B]PQB12 [/B]
S: 3,26V 
G: 4,66V
D:3,16V 

[B]PUB1[/B]

1 - 2.26v
2- 0v
3 - 0v
4 - 0v
5 - 0v
6 - 0v
7 - 0v
8 -0v
9 - 0v
10 - 0v
11 - 3.03v
12 - 0v
13 - 0v
14 - 0,04v
15 - 0,04v
16 - 1,8v
17 - 1v
18 - 19.02v
19 - 5.13vv
20 - 5.13v
21 - 0v
22 - 0,04v
23 - 0,04v
24 - 5.01v
25 - 0v
26 - 0.04v
27 - 4.87v
28 - 0v
29 - 3.27v
30 - 4.66v
31 - 3.17v
32 - 3.17v

...this time PIN 18 and 19 were safe and i do not short them...maybe because i got 9 more of those ic's LOL

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

PQB11 is an N-channel mosfet and the GATE needs to be a more positive voltage that what it is passing between SOURCE & DRAIN to turn on. So for this case ~25V will be a good value.

With the GATE @ 4.66V, this mosfet will remain OFF.

The GATE voltage is created an a boost / charge pump inside the PUB1 device.

1) Confirm that PUB1 is soldered on properly. Flux it -> reflow it till it dances over the SMD pads with a gentle nudge of the tweezers. Never push the device with force otherwise the SMD pads will tear off, making it difficult or impossible to repair.

2) Test again.

3) See attached.

Pin # 2 of PUB1 is ACOK. Confirm the voltage @ PRB12, pin # 1. This should be ~5v13 = same voltage as pin # 19 of PUB1.

Remove all power. Check the resistance of PRB12 which should be ~100k.

4) With no power, check the resistance of the mosfets:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

for PQB11, PQB12, PQB1, PQB2 and PQB13.

Post the readings. Checking for a low resistance on the above tests which will mean a defective mosfet.

With the gate having such a negative value, the mosfets @ PQB11 & PQB12 should be OFF yet there is ~3v leaking through somehow.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Hi big thank You for the tips You are really good human karma will come back to You

The masurments are below :

PRB12 - he looks ok but i was in a shop to buy some capacitors and resistors so i replace him with the new one

Resistance is exactly 100K
Voltage is 5,12v

PQB11

source (1-2-3) & drain (5-6-7-8)
3.5 Mohm ( with positive probe on S ) / 4.63 Mohm ( with positive probe on D )
---------------
source (1-2-3) & gate (4)
7.12 Mohm ( with positive probe on S ) / OL Mohm ( with positive probe on G)
---------------
gate (4) & drain (5-6-7-8)
OL Mohm ( with positive probe on G ) / 11.9 to 12,6 Mohm ( with positive probe on D ) ( varies and it is strange that is showing different results )
---------------

PQB12

source (1-2-3) & drain (5-6-7-8)
3.42 Mohm ( with positive probe on S ) / 4.02 Mohm ( with positive probe on D )
---------------
source (1-2-3) & gate (4)
6.93 Mohm ( with positive probe on S ) / OL Mohm ( with positive probe on G)
---------------
gate (4) & drain (5-6-7-8)
OL Mohm ( with positive probe on G ) / 11.03 Mohm ( with positive probe on D )
---------------

PQB13 PQB1 PQB2 ...

all of them give different results and the value is dropping to 0 from negative to positive

for ex PQB13
---------------
gate (4) & drain (5-6-7-8)
OL Mohm ( with positive probe on G ) / 14.73...14,26...14.66 Mohm...AND MINUTE LATER IT IS SHOWING 10MOHM AND DROPPING DOWN ( with positive probe on D )
---------------


maybe that PUB1 is damaged due to overheating or something...i will replace him with the new one

[mon2]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Mosfets with the high Mohm readings are good. Even with K readings or "OL" (over limit for the selected scale on your meter) are fine.

Yes, if you can, replace PUB1. You can protect the surrounding parts with aluminum foil or polymide (kapton) tape so they do not go flying off the PCB.

Flux and high heat with low to medium air pressure to remove without tearing off the PCB pads and to apply the fresh device.

After the replacement, measure and post the voltages present on PUB1 with the charger. Do inspect for any visible solder faults before applying power.

Take your time for a quality soldering of the PUB1 device.

[madfreak]

Re: Acer AN515-54 won't power on, no leds, no fan spinning, black screen

Hi, it is exactly like You said. The soldering of PUB1... i have overheated that chip the first time when i replaced him probably or the soldering was poor.

After double check the soldering of the PUB1 ( but i replace him to the new one ) that IC ( second new one ) came back to life

I think that nfortunately the PCH is bad on 99% because that is only thing which is heating after voltage injecting and after connecting charger.

But after all... there is a progress ... the LED-s are ON and the computer reacts to the power button...but the fans are not spinning and nothing more is happening ( black screen and so on ).

I will try with a PCH replacement i think in near future so i will look for a motherboard to get that PCH chip.

Thank You once again for a help, and if there will be a progress i will let You know.

Have a wonderful day