Dell xps 9560 doing fireworks

[Hanma]

Hello everyone .

A couple days ago my trusty laptop decided to die. I've the habit of sleeping with the laptop by my side with a movie.
That particular night I woke up, closed the laptop, removed the charger and got back to sleep.

The morning after, when I tried to power it on, it only gave me some orange blinks. Nothing on screen.
I unscrewed the backplate and immediately notice a blown component "PL500", which should be a power inductor.





While I was checking for voltages, (Main power rail and 3.3 were present) I tried to check with my finger if something was getting warm. The gpu was heating up along with a big coil above vram.

Then I removed the charger to flip the board upside down, and when I replugged it, another inductor "PL900" blow under my very own eyes, which also caused damage to the IC close to it "PU900".





Do you have any idea what might have caused it?
Kinda scared to plug the charger again now

[mon2]

Re: Dell xps 9560 doing fireworks

OMG. Remove all power. Meter in resistance mode.

Measure the resistance to ground of each and every inductor. Looking for a low resistance reading = shorted component on that power rail leg.

The pics look like there is horse manure on the board. Consider to use IPA and a cotton swap to clean it up to make it nice and shine.

[todenkopf]

Re: Dell xps 9560 doing fireworks

Also check charging port and it's wiring if present.

[Hanma]

Re: Dell xps 9560 doing fireworks

First of all, thank you for reaching out.

Yesterday I checked the inductors and some capacitors.



Here's what I've found:

The big inductor "PL501" is not shorted (80 ohms), the capacitor PC513 is shorted though.



Then I measured the coils near the CPU, which beeped but measured above 1 ohm.



Lastly, "PL 901" and its capacitors are completely shorted; it should be the 1v power supply for the gpu, but i'm not sure.

[todenkopf]

Re: Dell xps 9560 doing fireworks

Cut PJP500, measure resistance on both sides.

[Hanma]

Re: Dell xps 9560 doing fireworks

Long week at work, but i'm back to study the motherboard. I cut it, and measured the coils again.

The only one that measured below 1 ohm is PL901.

Here's a list of the other measurements:

PL501: gives a measurement over 200 k ohm
PL701: 200 ohm
PL1000: 2.4 ohm
PL1002: 1.6 ohm
PL1003: 1.6 ohm
PL1200: 2.4 ohm
PL1201: 2.4 ohm
PL1500: 60 ohm

[todenkopf]

Re: Dell xps 9560 doing fireworks

Good, now cut PJP900, check resistance on PL901. If it stays at 1 ohm, feel free to remove PU900 and recheck resistances on shorted caps and PL901. Do it carefully, try to not damage board.

Then remove PU500, after that check again PC513. If short is still there, it means that we got short circuit on 3VALW.. IF there will be kOhms, we can go further.

[Hanma]

Re: Dell xps 9560 doing fireworks

Here I am.

Removed PU900 with hot air (since it was damaged as shown in the pic) and took measurements again.

PL901 = 208 k ohms

PL501 measures 255 ohms
pc 512 420 k ohms
pc 513 5000 k ohms

[todenkopf]

Re: Dell xps 9560 doing fireworks

Now, I guess, its time to clear the motherboard and restore traces, especially around PU500. Also, it seems that the resistor marked 4R7 need to be replaced.

[Hanma]

Re: Dell xps 9560 doing fireworks

Thank you toden,

Yesterday I checked also PU400 and the capacitors nearby, because it's the power supply that outputs 3valw and 5valw. Everything seems okay there, nothing shorted to ground.

How would you restore the the trace? I have bought the blown inductor (PL500), wouldn't it work if I soldered it on top of the existing pads?

Tuen I have to buy the chip for PU900, which is the SYX196DQNC Qfn 10, also used for PU500.

[Hanma]

Re: Dell xps 9560 doing fireworks

Update, I found the SYX196DQNC on aliexpress.

Should I desolder the 4.7ohm resistor to check if it's working?

[todenkopf]

Re: Dell xps 9560 doing fireworks

Hey! First of all clear all the soot, cuz it is conductive, then you can extend any burned trace with wire, pay attention to suggest possible current flow and consider proper diameter of the wire.

About resistor: just measure it in ohmmeter mode, but it looks already damaged so could be tens of ohms now.

[Hanma]

Re: Dell xps 9560 doing fireworks

Already cleaned the board with isopropyl alcohol. The copper is not completely ripped from the board on PL500, so maybe I could be fine just with soldering the inductor on top of that.

I measured the resistor and it measures exactly 4.7ohms, so it's fine luckily.

Edit: I also measured PU900 and with the help of a schematic I measured it; correct me if I'm wrong but the pads I highlighted shouldn't be connected.



The schematic isn't exactly the model SYX196DQNC, I believe it's a new model of the same chip but it should work the same.

[todenkopf]

Re: Dell xps 9560 doing fireworks

PU900 definitely fried...

[Hanma]

Re: Dell xps 9560 doing fireworks

Yeah. I don't really know what might be the fault though. I ordered the IC's, and already have the power inductors PL500 and 900 ready to be soldered.

I'm worried once I solder the components back on the board it's going to go kabooom again .

PU500 is the ic that generate the 1valw. PU900 generates 1vs_gfx ( what does "vs" mean? ).

[todenkopf]

Re: Dell xps 9560 doing fireworks

Yeah. I don't really know what might be the fault though. I ordered the IC's, and already have the power inductors PL500 and 900 ready to be soldered.

I'm worried once I solder the components back on the board it's going to go kabooom again .

PU500 is the ic that generate the 1valw. PU900 generates 1vs_gfx ( what does "vs" mean? ).

I am not entirely sure about this, but usually "S" in signal name means "suspend" state.

[piernov]

Re: Dell xps 9560 doing fireworks

VS are often S0 rails (i.e. active when the machine is powered on).