HP 250 G9 - short circuit 100%

[Cicciotest]

Good morning guys.
I made a mess. I opened the new laptop, replaced the NVMe SSD, and closed it. When I plugged in the power cord, I saw the orange LED glow dimly several times, so I immediately unplugged it. I could also hear a strange buzzing sound coming from the laptop. Then I opened it again, and only later noticed that underneath the SSD was an aluminum plate that touched practically all the underlying components... what a disaster. I still don't understand how I didn't notice. Anyway...

I thought, okay, I'll just remove the plate and go. But now the power LED won't even turn on. It's completely dead, no lights, no LEDs.

I tested the power supply with a multimeter and it's perfect at 19.9v. I tried a second HP power supply I have at home for good luck with same voltage + ampere, but the result is the same: no power LEDs and no feedback wen i press power button.
I also removed the battery and tried a reset with the power button. I left it unplugged all night without the battery and cable, but the result this morning is the same.
So I made one or more shorts down there...
With the multimeter I can see that the 19/20V is reaching these red points, but then I don't know what to do and I can't figure out which component needs replacing.... Can you give me a hand, please?


This is the motherboard:

[Cicciotest]

Here a zoom of power entrance area and SSD area where i placed the ssd plate... hope you can see better.
in the rear side of the motherboard there is nothing, is completely smooth.

[Cicciotest]

THE MOTHERBOARS MODEL IS: IPA50 LA-K203P REV2.0

[ianbak]

The power from the charger is reaching the mother board - that's what you're measuring on the red wires.
There's a pinned thread here https://www.badcaps.net/forum/troubl...arging-circuit that explains where things go from there.

[Cicciotest]

The power from the charger is reaching the mother board - that's what you're measuring on the red wires.
There's a pinned thread here https://www.badcaps.net/forum/troubl...arging-circuit that explains where things go from there.

I read it but I can't translate the diagrams very well, in any case I understood from there, that I have to test the MOSFETs of the main power circuit, I tested these and they are ok:
there is nothing else on this side.


Instead on the top side, near the power connector, I tested these small mosfets but I got some strange readings on two of the 3:


Also on this side these MOSFETs give me continuity:

[Cicciotest]

In the meantime I tested the continuity in the coils, the red ones give me continuity, the green ones are ok:
Those mark in red with arrow in CPU, i think that are OK becouse yes, there is continuity but the resistance value is really low.
Also the Fuse (FU1 753J) is ok.

[Cicciotest]

i think that there is too many componente damaged here... too many componente damaged.
Mosfet and Ceramic capacitor that responds with low resistence, i have to remove all of them and test out of the board... anyway... i have to give up...

[mon2]

You are measuring the multiphase cpu power rails. This region, by design, will be with a low resistance. What is the exact resistance you are measuring here?

ps: I am travelling through Asia on business and have limited time to view the posts till my return. If you read 0 ohms here to ground then the cpu / pch is very likely shorted (dead).

[Cicciotest]

Hi, thanks, yes, I figured those were CPU-related, so I ignored them. No, I don't have 0 ohms, but something like 0.6-0.4 ohms, sometimes even 1 ohms, but I saw up close that all those MOSFETs are buck converters and therefore share pins, hence the continuity.

Now... I should start again from the power connector. But I don't know which components to test and how to do it properly.
If I had a thermal imaging camera, I probably would have already solved the problem by injecting 1.2 volts into an input point.

[Cicciotest]

Today i've spend some time to test ceramic capacitors, those in RED are all in 0ohm and continuty, maybe i write the code of the label in the motherboard:

Beginning from LEFT-BELOW in clock order, so, going up and then in the right side:
- PL12
- PL303 + PL304
- PL305
- PLG02
- LL2
- PLM2
- PL2501
- PL13 + PL14
- L5 + L6

Is is really strange that all thees line of capacitor give 0 ohms, sems all under a circuit that is in short... but why? Are really all of these in shorts or maybe is there a component before of them that put in short the circuit?
Below i attach a clean motherboard photo:

[Cicciotest]

Sorry, the red ones are in continuty and 0 ohms, and i've listed them with their code.
All the green ones sems to be good.

[Cicciotest]

Any suggestions guise?

[reformatt]

No schematic available for this board but LA-K201P seems close. You'll need to locate the main power rail after the first two MOSFET's to see if it's shorted. PQB13 looks to be your battery FET, PQB11/12 are your first two. PQB3 looks to be your current sense resistor for the main power rail. Is this shorted to ground, if not do you get 19V when power is applied?

The top two coils PL301, PL302 will likely be your 3.3V and 5V rails. One of the IC's PU301/302 chips will probably have AWV on it (that is SY8286BRAC). Should have 3V on pin 17 - this is your LDO voltage for your EC. Need this at the minimum for your board to turn on from power button. I'm only guessing here, but you should get the gist.

[Cicciotest]

thanks sO much, but sorry, i cannot see PQB13 nor PQB11/12 or PQB3, i only find PQB2 on my board...I'm afraid i think it's quite different. I looked at the schematic of the K201P with a CAD viewer and identified the PQB13/11/12s, etc., but they're not on mine board, at least I can't find them, and the component composition isn't similar to the one on the board.
I've looked up all the abbreviations, and the only PQB I can find in my board is the PQB2 above the keyboard flat connector 😓.

[reformatt]

First image in post #5? It has PQB11 etc and PRB3 clearly marked. Is this from a different board then?

[Cicciotest]

First image in post #5? It has PQB11 etc and PRB3 clearly marked. Is this from a different board then?

Woops, sooorry sorry!!!!! You right those are in the back side of the board, you're absolutely right, i show you all i can test with power supply connected, see below, i really do not understand what are happening here: The yellow ones are literally "millivolts" only the 4 common pins below the PQB11 are 19v.


Really thanks for help in advance!!

[reformatt]

No power past the first MOSFET PQB11. Is your main power rail shorted? Check PRB3 resistance to ground with no power applied.

[Cicciotest]

No power past the first MOSFET PQB11. Is your main power rail shorted? Check PRB3 resistance to ground with no power applied.

Yes! ok!
The resistor PRB3 to ground without power supply measure 10 M ohm in both poles, that goes down slowly slowly (but always high values) there is no continuity (between both two poles of the resistor and ground).

[reformatt]

So you're getting no gate drive to PQB11. Check PUB1 which is likely a BQ24780 or BQ24780S. So with charger plugged in, measure the following:

Pin 28 - VCC
Pin 5 - ACOK
Pin 6 - ACDET
Pin 24 - REGEN

If VCC is missing, then check PDB1.

[Cicciotest]

I left out a detail last night, sorry, I don't know if you saw it from the photo, but the 19V are also on the south pole of the small ceramic capacitor to the left of the PQB11 MOSFET (they are on the same track), but the pole north of the ceramic capacitor measure around 20 millivolts.