[SOLVED] ASUS UX31A won't start. Black screen, no LEDs, buzzing sound coming from motherboard when AC adapter is plugged in.

[Romanio0089]

Hello, I need some help here.
My ASUS UX31A won't start anymore after a fan cleaning session. At first, after reassembly, there were the power LED, F2 LED, and Caps Lock LED all lighted up but with a black screen. Now, it became worse, black screen, no LEDs, and a strange buzzing sound coming from the motherboard when AC adapter is plugged in. AC adapter LED is green and sometimes, is orange but if I unplug it and plug it back, it becomes green again... I tried all troubleshooting I could find on internet.

Here's what I did yet :

· Electrical discharge - unplugged battery, pressed and hold power button for 1 minute, plugging AC adapter and test.
· Trying to boot without battery.
· Unplugging and plugging back all motherboards connectors.
· Checked from burnt or damaged parts on the motherboard. Nothing found there.
· Pressing and holding power button for 30 seconds.
· Remove SSD and tried to power on.
· Disconnected IO board and tried to power on.
· Verified keyboard and power button connector. Nothing is loose there. I reseated it just in case and still nothing.

Nothing worked there so I need help.

Maybe the power button has gone bad, so if you know what pins to short to power on the laptop, im interested. The buzzing sound I think comes from the chip marked JC EC 225. That's the marking ON the chip though and I couldn't find anything about it online. There is no other markings around the chip...

Here is a schematic if needed : schematic link here
Motherboard model : UX31A2 MAIN BOARD REV. 2.0

Thanks in advance for your time.

 

[lga1156_ftw]

might be shorted power jack, (where u plugin power cable), check near that area see anything strange? Is your power brick giving right votltage check with multimeter?

 

[Romanio0089]

might be shorted power jack, (where u plugin power cable), check near that area see anything strange? Is your power brick giving right votltage check with multimeter?

Thanks for taking your time to answer. Power jack is fine since I tested it with the multimeter and it looks basically fine. While I was checking that, the buzzing sound suddently stopped and the board was starting to burn ! I investigated and I couldn't find where the steam was coming from so I decided I was going to abandon this board. I'll buy a new one later. Thanks.

 

[lga1156_ftw]

Did you try To boot without the lcd cable connected

 

[Romanio0089]

Yes. Nothing did it unfourtunatly.

 

[lga1156_ftw]

Component level repair is very hard. Only thing on the easier side is replacing the dc jack and components near it, sometimes there is a short on the dc jack causing problems in that area.

 

[Romanio0089]

That's totally true. But when I cleaned the PC, I didn't touch the area of the power jack. Thanks for answering but i'll just replace the board because repairing a board that is steaming, no thank you.

 

[lga1156_ftw]

When you cleaned the fan etc, did you disconnect batteyr when doing it?

 

[lga1156_ftw]

Ive seen zenbook with this issue like here: https://forums.tomsguide.com/thread...therboard-and-microburn-hidden-defect.146306/
Never got that to work and forgot the issue even, there was component with burn marks

Might of just been defect which was unavoidable

 

[Romanio0089]

Yes. Before doing anything, I carefully disconected the battery. I'll take a look at this thread. Thanks a lot for helping.