Asus UX490U laptop blown (caps?) on power board.

[odtech]

Greetings friends.

I was given this nice little laptop and would like to revive it if possible but i'm stuck identifying blown components. I'm very new to the repair game so i'm proceeding very cautiously.

I don't know the history of this laptop and the donator didn't elaborate what happened but it seems some moisture got into the USB C charge port and the result was what looks like some blown caps. The tell is some gunk inside the USB C port and corrosion on the outside as well as what looks like corrosion around the blown components.

Any guidance on proceeding or should I keep looking for the schematics?

If all else fails i can just replace the whole board, they are not too expensive on ali.
Attached picture of the damage. Just checking all the caps I don't find any shorts on the power board or the motherboard.


Thanks in advance.

[Stevedb]

Re: Asus UX490U laptop blown (caps?) on power board.

Remove the shorted cap and measure resistance on all coils to ground, see that usb c port is clean and no damage in the port. Put all values on hd picture . Resistance need to measure without power . And on 200 ohm scale. Put all the values on hd picture.

Then people can see what be the next step.

[odtech]

Re: Asus UX490U laptop blown (caps?) on power board.

Remove the shorted cap and measure resistance on all coils to ground, see that usb c port is clean and no damage in the port. Put all values on hd picture . Resistance need to measure without power . And on 200 ohm scale. Put all the values on hd picture.

Then people can see what be the next step.

Hello.

Thanks for the replay and sorry for the delay.

Here is the requested information. I've connected the IO board with the main board via it's flex cable before taking measurements. There is no coils/inductors on the IO board or none in a package i recognize as one in my limited experience.

Across the leads my multi meter measures 00.3 on the 200 scale. I had difficulty taking pictures of the measurements since nobody around to hold the camera so i will list the values below and attach a picture with the coils numbered. I can take clearer pictures of any requested area of the board but sadly I only have my phone camera which doesn't take great macro pictures.

Coils.

1. Out of range
2. 1 Ohm
3. 14.2 Ohm
4. 8.9 Ohm
5. 8.9 Ohm
6. 199.6 Ohm
7 49.3 Ohm
8 190.3 Ohm



Thanks much

[Stevedb]

Re: Asus UX490U laptop blown (caps?) on power board.

How much resistance you have on main power rail ( current sensor) to ground , resistance values look very low except one coil. Especially the one with 1 ohm. You can use and app calles cosy magnifier and microscope for good close up pictures.

[odtech]

Re: Asus UX490U laptop blown (caps?) on power board.

How much resistance you have on main power rail ( current sensor) to ground , resistance values look very low except one coil. Especially the one with 1 ohm. You can use and app calles cosy magnifier and microscope for good close up pictures.

If you look at my original photo of the damage. Is the current sensor perhaps the small black component to the left of the damaged caps?

That area is directly next to the usb c charge port on the IO board but nothing is labelled so hard to ID.

As for measuring the coil resistance. I'm not sure why but i'm getting different results now. I'd have blamed my multimeter but not all the measurements is different and i've done nothing to the board besides setting it aside until now.

1. Out of range
2. 1 Ohm
3. 10 Ohms
4. 6.8 Ohms
5. 6.8 Ohms
6. Out of range
7. 20 Ohms
8. Out of range

The track under the 1 Ohm coil seems to lead of to the CPU. As I understand it very low resistance is to be expected there?

Microscope is on my shopping list, i will get one soon but in the mean time I will try the app.

[odtech]

Re: Asus UX490U laptop blown (caps?) on power board.

How much resistance you have on main power rail ( current sensor) to ground , resistance values look very low except one coil. Especially the one with 1 ohm. You can use and app calles cosy magnifier and microscope for good close up pictures.

Thanks for the willingness to help.

I decided to just try powering the laptop on after removing the blown caps on the IO board. I was slightly worried about letting the magic smoke out but nothing surprising happened besides the laptop powering on. The CPU heats up, caps lock turns on and off and when i press the power button a second time it switches off so it has finished posting and waiting I assume at the "no HDD" error since it has no HDD/SSD installed.

The no display is two tiny blown parts (I think they are resistors since they are black) at the display connector which I will only be able to replace when i get a microscope or maybe a stand for my phone with the recommended app.

Now as for the missing parts, I've seen a Youtuber say if he finds them he just removes them and doesn't replace because it's better for the board without specifically those small caps than it is to heat the board up and replace it. Thoughts?

[odtech]

Re: Asus UX490U laptop blown (caps?) on power board.

Hello friends.

I've have returned to this after taking a detour in trying to fix with a bios flash. My previous assumption was that it is posting but the display is dead but that was wrong.. The blown resistors was on the keyboard connector, not the display connector.

I beleive i know what the issue is now but it seems Asus doesn't like people repairing so I'm not finding any schematics and the markings on the component I beleive to be faulty doesn't bring up anything significant on google.

I beleive it's the power management chip for the cpu that is faulty since i'm measuring power on caps leading to it but nothing after the chip on the CPU side. All power rails is present on the board, i'm getting 1.5, 1.8, 3.3, 5, 7.9 and 19 volt
Could someone perhaps ID this part for me?
I marked it with a red dot and since my camera isn't the best the numbers on it is as follows.
"MPHN
8690
1329
C"

Thanks in advance.

[mon2]

Re: Asus UX490U laptop blown (caps?) on power board.

MPS # MP86901

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[Sephir0th]

Re: Asus UX490U laptop blown (caps?) on power board.

i really don't have the intention to stop the party, but the 1Ohms Coil indicates that the RAM Chips and the Memory Controller inside of the CPU are shorted...

I'd check to what controller it is connected with Phase Pin to identify this power rail and make sure what it supplies.

[natic]

Re: Asus UX490U laptop blown (caps?) on power board.

i really don't have the intention to stop the party, but the 1Ohms Coil indicates that the RAM Chips and the Memory Controller inside of the CPU are shorted...

I totally agree.

Remove this coil from the board and measure the resistances to ground on both pads on the place of this coil.

And specify the motherboard marking code. It's marked on the bottom side of the board.

[odtech]

Re: Asus UX490U laptop blown (caps?) on power board.

i really don't have the intention to stop the party, but the 1Ohms Coil indicates that the RAM Chips and the Memory Controller inside of the CPU are shorted...

I'd check to what controller it is connected with Phase Pin to identify this power rail and make sure what it supplies.

My toolset isn't realy ready yet for doing this kind of trace, the board is small and densely populated. My main problem is I don't have a microscope yet and multimeter probes is too bulky. I'm going to sort both things soon.

I totally agree.

Remove this coil from the board and measure the resistances to ground on both pads on the place of this coil.
And specify the motherboard marking code. It's marked on the bottom side of the board.

The pad facing the cpu has 11.5Ohm on the 200 scale and the opposite pad has 1.5Ohm on the 200M scale.

Is the verdict still shorted cpu?

[natic]

Re: Asus UX490U laptop blown (caps?) on power board.

Is the verdict still shorted cpu?

Probably not, but first specify the motherboard marking code to make it clear.

This sticker is not a motherboard marking code.
It should be printed in white directly on the PCB laminate (for example as in the following picture).

[Th3_uN1Qu3]

Re: Asus UX490U laptop blown (caps?) on power board.

I beleive i know what the issue is now but it seems Asus doesn't like people repairing so I'm not finding any schematics and the markings on the component I beleive to be faulty doesn't bring up anything significant on google.

Yes and no. It is true that schematics for ASUS devices have been scarce in the past few years, they prefer publishing "repair guides" which are nearly useless, but most boards still have boardview files available which you can view with a piece of free software.

I see you are new to laptop repair so let me tell you what those are: Boardview means physical representation of the motherboard along with what part is connected to what other part and with all the names for voltage and signal lines and such. Boardviews are actually more helpful than schematics of you ask me.