How do I test the motherboard on a laptop with a broken screen?

I've got an Easynote LJ71 which I've been tasked with repairing. The screen appears to be dead. The machine powers on, but the screen does not. I can't even see a tonal change like the screen going from off to on/black. I also don't hear any windows sounds, beeps etc. There's nothing on the screen.

I've tried connecting to an external monitor by VGA and HDMI, but I'm not getting anything. I've tried the key combination on the keyboard which should launch the external monitor, but nothing happens.

I was about to go and buy a new LED screen, but what if its a motherboard issue? How do I test this? The screen won't work, and video out won't work - so how do I know if it works at all?

EDIT: I've made the question a little more clear (hopefully)

roryok

Posted 2013-11-20T11:44:50.207

Reputation: 672

Normally, you'd remove all peripherals and extra hardware (remove HDD/SDD, RAM, Optical Drive, Wireless card, etc) and try booting it up. If that works, you can add back a single piece, check if boots, repeat this sentence. If it doesn't work, you can be fairly confident it's something on the mobo. Most laptops have the gfx and such soldered to it, so that's where it's hard to confirm beyond that general area. – nerdwaller – 2013-11-20T12:16:25.270

You say it powers on, so do you see the POST or splash screen? Can you get into BIOS? Is there a display if booting to an Ubuntu or Windows CD? Any physical damage to the outside of the unit? – CharlieRB – 2013-11-20T12:19:17.290

sorry @charlieRB, I guess I wasn't clear enough. The screen appears to be dead. There is no display. I can't tell if that's the only issue though, as I can't tell how else to test the machine. – roryok – 2013-11-20T15:03:00.850

I'm just trying to understand what you mean by "it powers on". Is that just lights? How do you know it is doing anything? Is there hard drive activity? If the lights come on but nothing else is happening, it doesn't necessarily mean the display is bad, it may be something else entirely. You may want to open it up and re-seat all connectors inside. – CharlieRB – 2013-11-20T15:11:58.710

I've already popped it open and reseated everything. It powers on, the hd light seems to show activity and all status lights above the keyboard (wifi etc) flash exactly once. The battery charges. As in, the battery charge light came on and the battery charged fully over the course of an hour or so. the battery charge light then went out. – roryok – 2013-11-20T15:22:39.503

Answers

First of all Check the RAM modules, open the back cover, clean modules and reinsert it. if this doesn't got worked then after connecting an external monitor and test. after connecting monitor check whether there is any key combination for switching display to external monitor

Renju Chandran chingath

Posted 2013-11-20T11:44:50.207

Reputation: 1 461

renju, the external monitor won't work as I already stated – roryok – 2013-11-20T15:06:39.317

It sounds like the same symptoms that I have experience when the GPU gets to hot and separates for the motherboard. The fix is called reflowing. The process requires a complete disassembly of the laptop to the bare motherboard then heat is applied in a certain fashion to reset the GPU back to the motherboard. This method I have done myself with success. It is reputed to only last for a while, whether months or years, has yet to be determined. Reballing is the sure fire way to fix it, but more costly too.

Jack

Posted 2013-11-20T11:44:50.207

Reputation: 391

I've already ordered a new motherboard, and it arrived yesterday. I'll take a look and see if I can see that issue on the old mobo. Is this similar to the issue the xbox 360 used to have, that could famously be fixed popping the motherboard in the oven for a few minutes? – roryok – 2013-12-04T07:59:39.183

Yes that is the same fix. The oven fix seems a bit more barbaric, though by the reviews works. The method I used is with a heat gun and an aluminum shield cut around the GPU, along with a copper shim between the GPU and heat sink. – Jack – 2013-12-04T12:27:57.590