HP OMEN 15-DC no power/charge

[seb83gtt]

Hello,

First attempt on MB Troubleshooting (Beginner here )
I bought this HP OMEN for parts with a faulty MB.
OMEN PN : 15-DC0997NF

Important points to notice before to start with troubleshooting : I got this unit without charger (specific 200W/10.3A for this model) and without peripheral components (RAM, WIFI, SSD, HDD).

I am currently using a 65W HP charger to check the MB. Want to know if I can recover this MB before investing in an expensive charger/RAM. And maybe that will become a problem in the next steps (If I recover power).

Symptoms :
Common issue : Plugged in, no power light no charge light.
19.5V pass the first Mosfets (but Noticed 25V on the MOSFET gates, normal ?)
3.3V is there (3.301), SR40B chipset warms up slightly when plugged (powered by 3.3V).
No 3.3V @ power button.
I get 5V on the Input connector, but it comes from a small regulator on the backside. I don't think the 5V rail is UP. 5V should be the Buck near the 3.3V ? but no volage measured in the area (No Voltage on the MOSFET gates).

One component detected very hot (I can't keep a finger on it) : 5 Pins S88P15, No info about this chip. (Find on the web this could be equivalent to G5243AT11U : Power distribution switch for USB line overload ?).
There is a short between pins 1 and 2 (OUT and GND) with <1Ohm to ground for both.
I think this could be the faulty component... or maybe the Capacitor between GND and OUT...

Pics :




So this is theorically what I would do :
Unsolder the component check if short still present (to determine if capacitor could be the cause) then if CAP is OK, try to short this remote switch (PINS 4-5 to 1) ==> This would remove Overload protection... until I find a replacement component.

Would like to get feedbacks before any action, as I also consider selling the laptop package (in the same state I bought it) for parts without touching it (I don't have Hot air soldering station). Thanks

[reformatt]

Re: HP OMEN 15-DC no power/charge

No schematics available for this board, so probably not the best one to start out with.

My advice is to do a physical examination of the board under a microscope. Somtimes corrosion can be very easy to miss. Then check for shorts to ground around the board. The fact you have no +3.3V on the power button is actually a good thing usually. Note resistances around the CPU/GPU will measure very low. But below an 1 ohm is usually a short.

[seb83gtt]

Re: HP OMEN 15-DC no power/charge

I already brush the board with a teethbrush + dry air in the dense components area. => No effect (even if that does not replace microscope inspection). Board looks really clean (No liquid or damaged component). Unfortunately I don't have Microscope.

What do you think of the overheating component ? Is that a good path ?
I think this short make the 3.3V to fall down.

[reformatt]

Re: HP OMEN 15-DC no power/charge

It's a good place to start. That IC may be getting hot because of a short on the output (most likely), or it is internally shorted. I use a thermal camera and 1V voltage injection as its the quickest way to locate the short. But if you don't have that, you'll need to use cheaper methods like the Rosin dispenser pen or plain old IPA.

[seb83gtt]

Re: HP OMEN 15-DC no power/charge


I removed the suspect S88P15 capacitor => Short still present
Update after S88P15 removal (board damaged) => Short still present.
Locating the short on the backside, unfortunatelly, the Chispet seems to be the cause.
End of Troubleshoot and repair attempts.

[corrize]

Re: HP OMEN 15-DC no power/charge

Hello, yes, bad motherboard for beginner. Gamer boards need very goods tools.
On the gamers board, I don’t start diag by mosfets, I start to check resistance at all coils (tp ground). If one close CPU or GPU is at 0 Ohms : bad (probably chip dead).
You can test in resistance mode caps under chipset, CPU and GPU, if the twice pads are at 0 Ohms : bad.
Chipset and CPU are linked, if one is shorted, the other can be too. That could be difficult to distinguish wich one is really shorted.

[piernov]

Re: HP OMEN 15-DC no power/charge

Nvidia 1000 series and newer will measure lower than 1 ohm resistance to ground on GPU VCore so it is not a good diagnosis in this case.
CPU and PCH rarely share power rails (sometimes a 1.05V rail) so one being shorted doesn't necessarily affect the other. It's possible that what killed the PCH also killed the CPU though.