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How to determine Mainboard Failure on Laptop?

post #1 of 3
Thread Starter 
My friend has the asus Q501L laptop and wanted to power cycle it and decided to open it up and unplug the battery. However when put back together, the laptop will not power on.

No LED is on
When Plugged into AC, will not power on.
Unplugged and re plugged all connectors from motherboard, none are missing.

Replacing the mainboard on this laptop doesn't seem that bad, however I want to know for sure if this seems like a motherboard failure due to a short or something. Any ideas/troubleshooting steps? Thank in advance!

EDIT - CPU gets hot when battery is plugged in, fan doesn't spin, no LEDS.
Edited by APhamX - 1/13/15 at 11:48am
post #2 of 3
Remove HDDs and all other devices. Test with different RAM. If you don't have a replacement CPU (which I imagine you don't) and the motherboard doesn't give any response, it's either your CPU or motherboard.

Also get a voltmeter to test the PSU.
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RPI Compy
(14 items)
 
Sister's rig
(11 items)
 
Family HTPC
(10 items)
 
CPUMotherboardGraphicsRAM
5820k MSI X99S MPOWER GTX 980 Ti 8x4gb 3000 MHz Crucial DDR4 
Hard DriveCoolingOSMonitor
Samsung 950 Pro Custom WC loop 480mm & 560mm Windows 10 ROG SWIFT 
KeyboardPowerCaseMouse
CM Quickfire TK Greens Corsair RM1000w Custom 3d-printed case Steelseries Rival 
Mouse PadAudio
CSGO Steelseries Creative Aurvana Live! 2 
CPUMotherboardGraphicsRAM
Amd FX 8320 Asus sabertooth 990FX Nvidia GTX 760 4GB g.skill ares 12GB 
Hard DriveOptical DriveCoolingOS
Samsung 850 EVO 250GB HP thingy Phanteks TC12DX Windows 7 
PowerCaseMouse
Raidmax 530w White FD R4 Logitech G400 
CPUMotherboardGraphicsRAM
AMD A10 5800k Asrock pro-4 m His 6770 1GB G.skill 2133 8GB 
Hard DriveOptical DriveCoolingOS
Samsung 840 ssd 128 GB Lg blu-ray combo drive Cooler Master Hyper 212 EVO Windows 7 
PowerCase
Raidmax 530w Silverstone Temjin 
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Reply
post #3 of 3
Hi,

First of all, test the AC/DC power adapter with a multimeter. It’s very likely that there is noting wrong with the laptop and your problem is related to the power adapter.

If the adapter tests fine and output correct voltage, disassemble the computer and remove the top cover.

As you see on the first picture, in my example the power adapter plugs into the DC-IN power jack which is connected to the motherboard via a harness.
In some models the DC-IN power jack is soldered directly to the motherboard.

Plug in the power adapter and measure voltage at the point where the DC-IN jack or DC harness (like in my case) connected to the motherboard.

If you are reading the same voltage as on the AC adapter, it means the power jack or harness works properly and the problem is related to the motherboard.

If there is no voltage, most likely there is a problem with the jack or hardness and it has to be replaced.

Test incoming voltage

By the way, in some case the problem could be related to the fuse which is usually located somewhere very close to the power jack/harness connector. You can test the fuse with a multimeter.

Laptop fuse on motherboard

If the fuse is bad, the motherboard will appear to be dead even if there is nothing wrong with the power jack and AC/DC adapter. If that’s the case, replacing the bad fuse should fix the problem.

NOTE:

This steps should be done only you are well experienced in disassembling laptops.
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