Troubles with HP pro x2 612 g2

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

I mean the one i removed, see the photo

Quite tiny once unsoldered for someone with shaky hands due to meds, believe me !
Just imagine that prior to this repair attempt, I wasn't even able to read the slightest info on a datasheet, I only changed usb and broken/ripped ports, replaced simple smd parts like fuses and little stuff following guides online, nothing more. I'm glad I learn so much with your help, it opens a lot of possibilities for my repair projects.

SO
Here are pics of the culprit.
Mesured directly, it has MOhs range resistance on S to G and G to D. But, when probing Source to Drain, only barely 10 KOhms.

[mon2]

Re: Troubles with HP pro x2 612 g2

it opens a lot of possibilities for my repair projects.

Good for you! My eyes are not what they used to be either and do need a new pair of glasses. However, no one can challenge my vision on tiny parts at the office - doing fine with close up. Still need to find a nice digital microscope (4k?) but the reviews and features vary so much.

On your mosfet readings, agree that the S-D sounds really low and is bad.

Any chance you have a micrometer ? To measure at least the physical size of this mosfet ? Interested in the length x width in mm so we can find a replacement. The replacement does not have to be the same but just compatible.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

yep, I have a micrometer. But, here it is metric system. I might have the two kind (15 years of reloading) I do it and edit.

So, Length, leg not included : 0.115 inch or 2.93mm
Width : 0.12 inch or 3mm

I can if needed wire an unfitting component from a place it can be snugged. I have very thin wires, even 0.02mm !

I have some donor boards, from laptop and netbook from the same gen more or less (2016 to 2017) so I can with luck find something which might fit/be compatible ? Here in France we don't have a lot of shops providing SMD components.

[mon2]

Re: Troubles with HP pro x2 612 g2

If you can post the measurements in metric (mm = millimeters), that is preferred.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

Read again my post, I measured in the two system, no problems
For instance, in front of me have two board that shared the BQ24780S IC. Maybe they could have some compatible mosfet ?

[mon2]

Re: Troubles with HP pro x2 612 g2

So your mosfet is a 3 x 3 mm mosfet that you have removed.

See if you can locate a similar sized mosfet from any of your donor boards -> then review the part number.

As per the TI datasheet, these are N-channel mosfets. This leg of the circuit will not see > 20V at anytime so any N-channel mosfet with 20V or higher support should be fine.

Before you remove the donor mosfet, do post the part number for a review -> then need to confirm with the meter, the resistance like before to be sure the donor is not defective.

have two board that shared the BQ24780S

100% correct but will the mosfets from the donor board fit your board being repaired ? If yes, do proceed.

Here in France we don't have a lot of shops providing SMD components.

Yeah, but you have @Piernov.

Parts like these are not very common, even in our markets. Of course there is Digikey, Mouser and Arrow but nothing like Aliexpress. Mobile Sentrix is in the right direction but the action is in Shenzhen and their mega high tech malls. Hope to visit their electronic parts malls one day...

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

so far, in 3x3mm I found :
E4VUA 2SQE19
H5GUB 2S0P01
G4GUE 6R0B05
A5VND 2S0J05
G4GUD 4S0910
E4GUD 350M19
Off course, I might have mistaken some 5-S and O-0

[mon2]

Re: Troubles with HP pro x2 612 g2

Review any of the mosfets linked to the 24780S on the donor boards. We know they will be N-channel if their gate pin is direct to the charger IC.

Then measure their physical size. Should be 3x3 mm.

If it is a fit, post their markings but it should function as a replacement.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

A5VND 2S0L10 is straight to BQ24780S
Seems fine, MOhms range resistance between S-D, D-G and G-S

[mon2]

Re: Troubles with HP pro x2 612 g2

Very good. Give it a try.

Be sure to use lots of flux and heat. Low air pressure so parts do not go flying. The pads will sink into the proper alignment.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

I replaced the mosfet and gave it a try.
It doesn't change anything. BUT
I removed the mosfet, check it, and checked its trace on the board. Before changing it, BQ24780S pin 26 reached this mosfet DRAIN with very little resistance. Now it won't anymore.
The TWO last components, pointed out with the toothpick on the photo, give infinite resistance.

[mon2]

Re: Troubles with HP pro x2 612 g2

With no power, measure the pcb trace resistance from the charger pin to this gate pin. The trace is likely visible from end to end.

Suspecting that the part is not soldered onto the pcb pads so you are unable to measure the expected ~0 ohms.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

I check that, but anyway I'm not even sure I told you the truth. I might be wrong. Source pad is still connected to pin 23, 26 and 27

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

I'm a bit lost

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

And.. I lost the new mosfet...

[mon2]

Re: Troubles with HP pro x2 612 g2

Do you believe the replacement mosfet is defective?

Check the resistance of the trace with one probe on the charger IC. Other probe on the pcb trace as it travels to the mosfet pin.

The green solder mask (paint) will not be conductive. So you can use the edge of a sharp knife to scrape the green solder mask.

Did you see any burn marks after plugging in the adapter?

For now, do not power up as we need to agree on the state of this mosfet replacement.

The resistance should be ~0 ohms from end to end.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

mosfet seems good
See, i took measures (Voltage) at the HIDRV and LODRV IC
When on dc, once I hot plug the battery the left one turns 11.8V from its drain into 8.3V at it source and 8.1 at its gate. the right one gets 8.3V at its drain, 0v at its source, and 0.5V at its gate.

If I unplug the battery, or power on only on battery, the left one gets 8.23V at source, 8.23V at drain and 8.1 at gate. 0v at source and gate on the left, 8.23V at drain

I know the mosfet replaced was bad considering its reading, but the problem of the usb c port being deactivated as soon as the battery is plug remains

[mon2]

Re: Troubles with HP pro x2 612 g2

These are N-channel mosfets so the gate must be higher than the source to enable.

From the measurements, the high side mosfet is disabled (off state).

Remove the battery and measure the voltage across the red and black wires. It is ~8v3 ?

Also confirm that REGN on the charger IC is ~6v.

The charger IC also has a BATPRES# which means if the signal is LOW, the battery is present.

Check that this signal is a low voltage on the charger IC. Do not do your glitch trick. Just normal battery seating.

If the charger does not detect the battery, the battery will not charge and the charge mosfets will not receive the boosted gate voltage.

[johnjohnjohnjohn]

Re: Troubles with HP pro x2 612 g2

Hello.
The pc no longer turns on on dc, even without battery plugged in
With battery plugged in only, it won't power neither now, but blinks on its power light. I'll first try to put back the leaking mosfet, like nothing was ever changed, to see if the pc goes back to it's pre-fix state. From here I suppose we will have a better idea of the problem ?

[mon2]

Re: Troubles with HP pro x2 612 g2

Yes, place the mosfet back and test again.