What hardware failure causes screen flicker on Aspire E1-572

Hi,
I am investigating screen flicker on a friend's Aspire E1-572. The effect is variable, sometimes its fine for several minutes then starts flickering. At worst the screen is dark but you can still just see the content. If I connect an external display via the HDMI port then that works perfectly - rock solid.

Following the advice given in various other threads on the site, I have re-installed the graphics card driver and tried booting into Setup (F2 after turn on). The screen still flickers even in Setup. So its a hardware problem. I've dismantled the machine and checked the screen cable and connectors. I'm as sure as I can be the the cable and connectors are OK.

Is the problem with the screen or main board? Any tests I can try to eliminate one or the other?

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GAMING6698

@RatleyRescue
You have already checked screen flickering occurs in laptop screen and External display working without any flickering.
So,
Laptop screen cable get loose or damage visit nearest service centre for replace

RatleyRescue

As noted in my original post, I have already checked the screen cable. It is not damaged or loose. There is no co-relation between moving or wiggling the cable or connector and the flicker on the screen.
I can replace the cable, screen or mother board until the fault goes away. I was hoping that someone would know for sure where the fault lies. There are many reports of hardware related screen flicker but I have not found one that reports how it has been solved. However as the screen cable is the cheapest component I'll try replacing that first.

RatleyRescue

Piter said:

Hardware failure is the likely cause when flicker occurs only when the laptop moves. Most likely, the screen cable is loose or damaged, but the inverter and backlight can also cause this problem. ... For the best results, take the laptop to a licensed technician or send it back to the manufacturer.
Otherwise check out post to see if these methods working to your issue.

GAMING6698 said:

@RatleyRescue
You have already checked screen flickering occurs in laptop screen and External display working without any flickering.
So,
Laptop screen cable get loose or damage visit nearest service centre for replace

Ok, I've changed the screen cable, including updating the iFixit guide. The screen still flickers. The new cable has made no difference at all.
Summary of actions so far:-
Checked and updated the screen driver - screen still flickers
Checked in Setup mode - screen still flickers
Checked in Task Manager - screen still flickers
Checked cable visually - no visible damage to cable
Waggling the cable - screen flicker is not related to waggling the cable
Replaced the screen cable - screen still flickers. And no, neither the original screen cable or the replacement are "loose or damaged"

Summary of Problem:-
Sometimes the screen is OK
Sometimes the screen is dark but you can just make out the image
Sometimes the screen flickers. It looks like the flicker is the screen going dark and then light again. It all goes together.
It is not related to what is being shown on the screen

So it feels to me that the problem is in the circuit that produces the voltage for the backlight.
Does anyone know how and where the backlight voltage is generated?

Oh and just to be clear, I am our village's Service Centre! I am quite capable of taking a PC apart and putting it back together. I am looking for information on what is the exact root cause of the flicker fault. When I know that then I can buy new parts to replace whatever is faulty.

Thanks for your help

RatleyRescue

Update of fix. Ordered a new screen and gave the laptop back to my friend while waiting for the new screen to arrive. When he got it home and booted it up the screen was absolutely fine. It stayed fine up until about 2 weeks ago, 5 months after I returned it.

So now I have fitted the new screen and the flicker is gone. I tried putting the old screen back in and the flicker returned. Put the new screen in again and the flicker is gone again. So it passes the ABA test; the fault returns when you put the suspect part back in.

So my conclusion is that if you get screen flickering, especially it it goes dark for periods, then just change the screen. I used the iFixit guide but found that you do not need to dismantle the base unit, just the screen part. So I've annotated the iFixt guide.