Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

[speggio91]

Hello everyone,

I've received from a friend this laptop that doesn't turn on or charge, no led indicator or amperage drawn from the external psu.

After visually inspecting the main board, i've found some burnt capacitors and resistors. After removing them I end up with this aftermath (see the attached photo).
In your honest opinion, is it worth trying to fix it? I've downloaded the schematics but I don't know if they are made for that exact pcb, from what i've seen on this forum, this issue is pretty common for this hp board, exept that in my case it went horribly wrong.

Do you have any suggestions to help me starting troubleshooting?
So far, i''ve measured the voltages of some mosfet pins nearby the messy area.
The pin #8 of PQ6 measure 19V, so there's no apparent short to main.
PU1 seem to be healthy too but I will need to check it better.

If anyone has any hints on where to focus the troubleshooting I'd be very glad to check the board.

I've attached also the boardview i've found online and the software to read it.

Thanks

[speggio91]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

Hello again, just a quick update on the measure I did:

PQ8:
-measuring in resistance mode and in diode mode show a 1ohm short between drain and source
-no short to ground in any pin
-drain to gate and source to gate resistance is always 625 and 600 ohm
-when connected a dc power supply, all G,D,S measure 19V


The burnt pcb layer that hosted the components PC29, PC20, PC30,PC31, is now a ground plane that didn't merge with the 19v upper layer line +AC_CHG_IN. I did isolate the layer with UV mask.

I tried to put 11V on the pins 4-5-6 on CN19 to see if there are any sign of life, after pressing the power button the DC jack led blink 3 times with no other sign and no amps are being drawned.

Do you think that PQ8 need to be replaced?

[speggio91]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

Update #2:

I did replace the PQ8 with a different mosfet from a donor board, the model is:
AON6426.

After pluggin back the DC and giving 19V, the DC jack led lighted up in a solid white colour, I tried to press the power button and the board powered on!

I tried to connect the battery but it didn't charge it. The Dc Led turned right after giving DC supply, after 2 seconds it returned in white colour with 0A drawned. If I tried to power on the board, after the bios post the led start to blink and still no signs of charge.

With the battery still connected I took measurements at PQ28:
13V at the source side, 19V at the gate, 0V at drain.

Then i've check every pins of PU1 and here are the measurements:
(battery still connected)
1 19.49V
2 19.49V
3 CMSRC 19.45V
4 ACDRV 25.30V
5 ACOK 3.35V
6 ACDET 2.77V
7 3mv
8 SDA 3.1V
9 SCL 3.1V
10 3.7V
11 13.5V
12 13.5V
13 13.5V
14 0V
15 2mv
16 REGN 50mv
17 17.8V
18 17.6V
19 17.8V
20 VCC 18.6V

Right after finishing probing, the DC jack led turned off, when I tried to power it back on I got 3 white blinks and nothing else.
I don't think I've shorted any pins while probing, I've double checked if there were fragments of solid solder but no traces of it.

Even without the battery the board act like that.

On PQ8 there's now no voltage at the source and gate, only 18.3V at drain.

I did check again the mosfet PQ28 and this are the measurements:
Gate: 10V
Source & Drain: 18.3V

I think the PU1 is dead, I can't think to another cause of this behaviour.
I will order a new BQ24715 and update the post when I will replace it.

If you have any suggestions or observation I'd be glad to read them!

[mon2]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

Yes. Agree. REGN voltage is not correct.

Remove all power. Check if there is a low resistance to ground on this REGN pin.

If not, replace this IC. This LDO output should be on.

Vcc, pin 20 appears a but low but there will be a slight forward diode voltage drop on this leg from the dc adapter input value.

[speggio91]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

The new chip is arrived and I did replace it.
The laptop is turning on again but it still won't charge the battery, that is deeply discharged.

I've connected the board to the power supply, connected the battery and I've measured again all the pins of PU1:

1 19.65 V
2 19.65 V
3 CMSRC 19.6 V
4 ACDRV 25.6 V
5 ACOK 3.33 V
6 ACDET 2.8 V
7 0V
8 SDA 3.1V
9 SCL 3.1V
10 3.7 V
11 13.5 V
12 13.5 V
13 13.55 V
14 0 V
15 0 V
16 REGN 6 V
17 18.8 V
18 13.5 V
19 13.5 V
20 VCC 19 V

I notice that REGN is finally back, but I don't know if the pin 15 should be at zero. Pin 11 is still high and that won't turn on the mosfet PQ28.

I've checked the resistor PR72 and it's ok. I've tried to read all the datasheed of BQ24715 but I didn't find an explanation on why that pin 11 is high when all the required tensions are there. Is there something i'm missing?
Maybe is the battery to be dead or so much discharged that the ic won't go low on the BATDRV pin?

Any ideas?

Thanks

[mon2]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

What are the voltage readings of the following ?

MBDATA
MBCLK

[speggio91]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

What are the voltage readings of the following ?

MBDATA
MBCLK

Both lines are at 3.1V

In my board PR81, PR80 are not present, same for R151, R156.

I've measured the voltage on R289 and R281. That voltage is present also on the R151, R156 place on the right solder pads that are connected straight to the U8 chip.

[speggio91]

Re: Hp Spectre x360 (Da0y0dmbaf0) burnt pcb - No power

I have a good news and a very bad one:

Good news: I've replaced the battery with a brand new one and the board finally charged and powered on without the ac adapter connected.
I did some power on and off tests outside the chassis.
I was so happy and I started to reassembly the board inside the chassis.

I did replace the cpu thermal paste, reassembled the heatsink, laid the board in the housing. I didn't attach the battery.

Here it comes the bad news:

after reattaching all the flat cables, screwed in the holding screws of the motherboard, I decided to power on the laptop just with the AC adapter connected.

After pressing the power button, nothing happened, the DC jack led was on but the power led didn't turn on as usual. I've noticed that the power button led turned on after 12 seconds and right after that, both power and dc jack leds goes off. Then, after a second, only the power jack led turned on again and the cycle repeats each time i try to press the power button. During all this no amperage is drawn by the board, the cpu/pch is not heating either.
The battery and all the charging circuit is still working correctly, there seems to be some issue with the startup sequence.

After reading the schematics last page about the power flowchart, down here you will find all the readings in the S5 state:

+3VPCU= +3.33V
+5VS5= +5V
NBSWON1= +4.9V - shouldn't it be +3.33V ?
EC_ON_OFF= +3.3V
5VS5_ON= +3.33V (it stay the same even after pressing pwrbtn) - very strange voltage
3VS5_ON= 0V (It goes to +3.33V after pressing power button)

SUB, SUC= don't know where to find those

+1.8SUS= 0V, even after pressing power button, no res to ground detected
+1.2VSUS= 0V, even after pressing power button, no res to ground detected

SUSON= 0V, even after pressing power button, no res to ground detected

HWPG= 0V, even after pressing power button, no res to ground detected

MAINON= 0V, even after pressing power button, no res to ground detected

DNBSWON= 0V, even after pressing power button, no res to ground detected
At pin 1 of R507, after pressing the power button, I've measured +3.33V (+3VS5) but after 3 second it goes down to zero. At pin 2 i measure always 0V
The resistor value is 4.7Kohm which is correct.

I think that when I reinstalled the cpu heatsink or the board in the chassis, I've somehow shorted or shocked something with electrostatic discharge. That compromised the super I/O chip. The odd thing is that the motherboard wasn't connected to any power source and the board was laying over an antistatic matte all the time i was testing it.

Do you think the super I/O chip is gone?


Thanks for your help you gave me through this journey