ASUS ViviBook X512F no power

[Simplebeans]

Hi,

I got myself hands on a Asus ViviBook X512F which the seller said has been liquid damaged that has no power. The motherboard number is 'X512FF' - Rev 2.2. I am using a genuine ASUS 45W Power Adapter. When plugging in power adapter there is no lights that illuminate and the machine does not power on when pressing the power button.

When I removed the motherboard from the chassis it seemed one of the components was completely burnt out! I have attached a picture below of the component which i have successfully removed, circled in white, this is the component that was burnt out on my motherboard. The connector to the left of this is the LCD connector. The issue i have is the component being so badly damaged i have no idea what SMD it is or its values. I have searched for the schematics and board view, yet to no avail.

Was wondering if anyone who has one of these machines/knowledge of/or can shine some light on this can help me out on this ideally if possible to identify the component incl. values so i can seek a replacement.

When doing a cursory inspection of the board there does not seem to be any voltage going to any of the main inductors on the board and from what i can see the power is reaching up to the second mosfet @ the initial buck converter at the power supply. The voltage then stops at that mosfet drain and does not appear on the source side of mosfet. I am thinking at the moment in time this is a consequence of the protection that’s built into the board and once i have replaced the burnt component this will then kick the board back into gear.

Any help would be appreciated.



P.S Also the image above is not a picture of my board, this is, for illustrative purposes only to show better the burnt out component.

[satishkumar]

Re: ASUS ViviBook X512F no power

marked component is Fuse

[Simplebeans]

Re: ASUS ViviBook X512F no power

marked component is Fuse

Thanks and any idea of the values for the fuse?

[mcplslg123]

Re: ASUS ViviBook X512F no power

To mee it seems like a coil. Make sure whether its a coil or fuse. Remove the part and check resistance on both the pads. If the resistance is high, you can solder similar fuse/coil(located near lvds connector) from any scrap board.

[Simplebeans]

Re: ASUS ViviBook X512F no power

To mee it seems like a coil. Make sure whether its a coil or fuse. Remove the part and check resistance on both the pads. If the resistance is high, you can solder similar fuse/coil(located near lvds connector) from any scrap board.

mcplslg123 that would be the most ideal scenario however the part was so badly damaged i was not even able to conduct any tests on the part. The observation I was able to make was when I have the cheer plugged in the 19V is flowing to the right hand side of the blown part (if you are looking at the picture I have attached) and on the left hand side of the blown part it measures 0V, so this inference also makes me think that it’s either a coil/fuse. But as I can’t measure I cannot tell.

[mcplslg123]

Re: ASUS ViviBook X512F no power

I think wiser to put a fuse but do check resistance on the pad where you are getting 0 Volts.

[Simplebeans]

Re: ASUS ViviBook X512F no power

I think wiser to put a fuse but do check resistance on the pad where you are getting 0 Volts.

Thanks so a couple of things i have done so far just to update, i had to remove the LCD connector because when plugging in the charger this was getting hot and upon closer inspection the PINS on the LCD connector on one side were damaged. Checking under the thermal camera to make sure I could see that this one side of the LCD connector was indeed getting hotter. So I have removed and plan on replacing that from a donor board.

As suggested I measured the resistance on both sides of the missing component and this is the readings i got (multimeter in resistance mode -20MΩ, black probe to ground and red probe to each side)

Right side: 3.00MΩ
Left Side: 0L

I also added a fuse to check things out and can see the 19V appearing on both sides now however, this is, in the absence of any voltages on any of the coils appearing. The 3.3V or 5V rails on the coils just above the LCD connector, the two that sit to the most left hand side of the board are absent. Again this has been observed from the donor board (X512DA) where these voltages are present and has a very similar layout kindred to those coils.

[mcplslg123]

Re: ASUS ViviBook X512F no power

It seems you have other damages as well. Start with dc-in fets voltage on S_D-G pins. Then, what is the resistance on 3v/5V coil in ohms mode?? Check resistance for 3V LDO pin.

[Simplebeans]

Re: ASUS ViviBook X512F no power

It seems you have other damages as well. Start with dc-in fets voltage on S_D-G pins. Then, what is the resistance on 3v/5V coil in ohms mode?? Check resistance for 3V LDO pin.

Ok so replaced the lcd connector, i didn't want to do any further testing until this was done. I have just checked resistance to ground on both coils, below are the readings(multimeter in resistance mode 20KΩ, black probe to ground point and red probe to each side of each of the coils):

5V Coil: 10.82KΩ
3V Coil: 7.89KΩ

Checking the mosfets on the 5V, 3V rails near the coils, both of the rails seems to be getting the 19V at the drain of 1 of the mosfets, nothing on the gate/source.

[mcplslg123]

Re: ASUS ViviBook X512F no power

The resistance seems ok. What is the current status of the unit?? No power??

[Simplebeans]

Re: ASUS ViviBook X512F no power

The resistance seems ok. What is the current status of the unit?? No power??

Yes no power, also when the charger is plugged in there are no lights illuminated.

[mcplslg123]

Re: ASUS ViviBook X512F no power

What is the exact consumption on your dc supply?
No battery attached

[Simplebeans]

Re: ASUS ViviBook X512F no power

What is the exact consumption on your dc supply?
No battery attached

On the USB tester i can see when i plug into the power it reads 0.00amps. So drawing no current.

[sect-sin]

Re: ASUS ViviBook X512F no power

Simplebeans,

I got the 2.1 revision of the board, the area looks exactly the same like on the 2.2 version. I measured the component out of circuit, it is definietly a 0 ohm resistor.

I have the exact same problem with my board, and wish us both good luck to fix it.

Cheers,

sect-sin

[mcplslg123]

Re: ASUS ViviBook X512F no power

OK. Lets make simple checks to begin with.

01.Measure voltage on Pin1-4-8 of dc-in mosfets.
02.Measure resistance on CLR.
03.Measure charging IC pins for ACN/ACP/CMSRC/ACOK/ACDET/REGN/VCC

[sect-sin]

Re: ASUS ViviBook X512F no power

Mcplslg123,

Thanks for your help. Will measure everything on Sunday.

Cheers,

sect-sin

[sect-sin]

Re: ASUS ViviBook X512F no power

Hi Mcplslg123!

I have done some measurements.

1. Already the first MOSFET, which is a QM3056M6 is a bit strange. Drain gets 19 V, but both Source and Gate have 3,142V. The resitance across Source and Gate is very low, 13 ohms only, though definitely not a dead short. There is a capacitor and resistor between Gate and Source, values unknown. If I try to power up, there is no change whatsoever.

2.
What is CLR?

3.
I have measured the charging IC, which is a TI BQ24780S:
ACN=3,145V
ACP=3,120V
CMSRC=3,145V
ACOK=6V
ACDET=2,649V
REGN=6,066V
VCC=19,28V

I think this looks good.

Cheers,

sect-sin

[mon2]

Re: ASUS ViviBook X512F no power

Resistance checks are always without power. Confirm this. Otherwise, the resistance is way too low and means this mosfet is defective.

Replace the QM3056M6 mosfet.

Continue to measure the resistance of the next mosfet that follows this one. It is possible that it is also defective.

Review the markings on the top side of the parts and order these for replacements -> consider to buy spares & also the charger IC. You will see likely 5 mosfets linked to this charger IC (2 x DCin mosfets + 2 x battery charging mosfets + 1 x battery mosfet) -> buy enough to replace each if required. They are common parts used on many logic boards = often are N-channel mosfets.

Aliexpress will have suppliers for the parts. If in a rush, we can try to find them on Mouser / Digikey / Arrow but they will be more expensive.

[sect-sin]

Re: ASUS ViviBook X512F no power

Hi Mon2,

I confirm that I measured without power, in-circuit. After reading your post, I de-soldered the first MOSFET, and measured again. Out of circuit it looks OK, megaohm range G to S and G to D, but the PCB still had 13 ohms across the Gate and Source.

So I checked the next MOSFET, which is a QM0930M, de-soldered it, and it has a dead short across all pins, so I guess this is the culprit. After desoldering, the resistance on the PCB between Gate and Source of the first MOSFET increased from 13 ohms to 2,2k, so i suppose this is the value of the unknown resistor.

I checked the battery charging MOSFETS and the battery MOSFET, all show resistances in the kiloohm range across their gates, so I guess they are OK. Nevertheless, I will order all three types from China. This will take awhile, but I will let you all know the outcome once it has arrived.

Are you sure I need to change the charging IC as well? Measurements showed it being pretty much alive.

I appreciate your thorough walk-through, thank you very much.

Cheers,

sect-sin

[mon2]

Re: ASUS ViviBook X512F no power

Good stuff. The charger IC is only for insurance. If needed, it will be available. Many single store shops on AliExpress can supply all of the parts you need to save on shipping.