Asus Laptop screen flicker on battery!

DonS

DonS

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Hey All!

A client gifted me a nice mint condition Asus X555LD. The issue with it is - only while on battery power, the screen flickers something aweful. As soon as you plug in the AC adapter, its perfect.

I bring this to the forums here because after a night of GoogleFu, I have seen *numerous* posts of people complaining about this issue and with this particular model.

Many things have been tried, with zero fixes.. so this remains a mystery!
What I have seen have been:

Change the battery - no effect
Replace the screen - no effect
Change power settings - no effect
Uninstall Asus Software - no effect
Replacement of motherboard - - no effect

That really does not leave much of anything! Has any one run across this issue before? What could possibly be causing this?

Thanks all! I look forward to the discussion.
 
Interesting.. I would certainly be tempted to wipe the drive and install Windows 7 to see what the results are.
Also, good call on a Linux Live CD. I will try this tomorrow and post back.
Thanks!
 
Alright, so loaded it up with a Linux Live CD. The behavior continues with the screen flickering when the AC Power is removed. So thinking hardware. Going to plug in an external monitor next and see what happens.
 
Had the exact same issue with a 13" dell. After a few months, it stopped working altogether. Now when you plug a charger into it, the charger shuts off. Tried a different charger with the same result. Chalked it up to a motherboard issue but I am considering trying a new battery. The battery for this model is 100 bucks so I don't know when.
 
I am not sure about it being a video cable. If a cable was damaged, I would assume I would see this happening with our without the AC adapter installed.
 
Good call on the BIOS. So.. in BIOS, when I remove the power cable, the screen goes entirely black. No flicker, just black.. Thought it lost power totaly, but as as soon as I plugged the AC power back in, the display came back on showing the BIOS screen still!
 
My immediate guess is that something with the LED driver circuitry is unstable when the input voltage goes below a certain level and the output voltage is dropping too low for the backlight LEDs, but that's not going to be trivial to find because you'd probably expect the backlight brightness to have an impact - it's not a direct simple connection like you'd find on LED bulbs.

A discussion on Spiceworks has one person claiming that reflowing the graphics chip resolved, it, but everyone else seems pretty sure that's not the case. I suspect it's more likely that in reflowing the graphics something in the power circuitry also got heated and reflowed.
 
Hey, I think you are on to something here. I did just check that and yes, with a flash light I can see the BIOS menus and toggle through them.
 
Something is wrong with the PWM backlight signal circuitry OR the charge controller itself. The square wave it is generating sounds like it is at the wrong duty-cycle or otherwise in some failure mode. The charge controller controls a lot of the power management stuff and the LCD back light is one of those things... so the PWM may be generated there or it may be passing a signal to an actual, separate IC.

I don't see any schematics available.. but I got you a boardview for it. www.boardviewer.com if you need a viewer. I attached the BD to this post.

IMO, it looks like you should start with the LCD connector J4502 (or is it J4503 On Top side?)on the bottom, of the top, of the boardview and work from there. Stuff around U4501 needs to be checked. Clicking on the objects and looking at the part or net listings on the right tells you some good info.

A multi-meter is a must, an oscilloscope would be ideal. If this is beyond your level of repair, then a new/used board is likely in order.
 

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I have this issue on my ASUS, it is the cable plug that is loosening. After pushing it a bit more, the issue disappears until it loosen again.
 
Umbra said:
I have this issue on my ASUS, it is the cable plug that is loosening. After pushing it a bit more, the issue disappears until it loosen again.
Click to expand...

What cable plug are you referring to?

Also thank you for taking time to explain and post schematics. But that is indeed beyond my pay grade. If it comes down to that, I think I will just eBay the thing!
 
Hmmm.... My Asus laptop is the opposite. Screen is lightly banded and flickering when running on AC and perfect on battery. (I should try a choke on the power cord.)
 
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I just visited a client today and she has same problem Asus TP550L
Screen flickers when not plugged in
I told her it might be an easy fix but after reading this I don't think so it's just out of warranty, she contacted them and they said sorry
It must be a M/B issue, it was an expensive laptop

Let me know if you resolved it
 
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