Asus X555L backlight shuts off when on battery

[Dannyx]

Re: Asus X555L backlight shuts off when on battery

Just yesterday I ran into this issue, but on a Lenovo laptop, so it's not strictly related to Asus apparently (which makes sense if you thing about it, because the problem lies with the display panel, not the MB). I don't remember the model, but it must be Y500 or something very similar, because I grabbed the boardview from here and it matches perfectly (big cheers to Vannix for providing it).

A colleague of mine brought me this Lenovo laptop to have a look at it after it took a drop and one of the hinges broke. Aside from that, there's also the issue of the backlight going off when running on battery, despite the laptop still running. Using the boardview, I tracked down the BL_ON and DIM signals and they were present in both cases at the connector, so I concluded the drop must've somehow damaged the panel which is now unable to sustain backlight operation on 7v from the battery, as opposed to 20v from the adapter, for one reason or another. It's a touch-screen display, so I didn't take the lid apart to inspect further, so I told the guy it's his choice, since I didn't want to risk cracking the digitizer...

[rotceh_dnih]

Re: Asus X555L backlight shuts off when on battery

I also have a 555 asus laptop with no/very low backlight on battery, 19v on the last few lvds pins with ac power then drops to 8v when power removed, will change the coil first thing tomorrow and report back!

Forgot to come back to update this post but the coil replacement worked on my first job and just today i had a 2'nd one come in , on the phone he said it loses backlight when power is removed.. i asked if it was a asus , he said yes, i asked if it was a 555 model , he asked how i knew lmfao... coil fixed that one up as well!

[Piruco]

Re: Asus X555L backlight shuts off when on battery

Forgot to come back to update this post but the coil replacement worked on my first job and just today i had a 2'nd one come in , on the phone he said it loses backlight when power is removed.. i asked if it was a asus , he said yes, i asked if it was a 555 model , he asked how i knew lmfao... coil fixed that one up as well!

Excellent all of you colleagues. Yesterday a x555ld arrived, same symptom. Check voltages, ratings, pwm, etc ... I will replace the coil and I will comment, I am very confident that it is solved. Greetings

[generic1]

Re: Asus X555L backlight shuts off when on battery

Could someone kindly explain to me in detail where the coil being replaced next to the CM509A chip is located? I've looked up diagrams and can't seem to pinpoint where it is to decide if it's worth attempting to open up my laptop to fix. Also, where would I be able to order a replacement 100 coil and how does it attach to the board? Thanks in advance.

[Dannyx]

Re: Asus X555L backlight shuts off when on battery

I think the coil in question is on the display panel, not inside the laptop. I haven't done this myself to confirm, but most seem to report it's on the panel and had great success replacing it overall !

[mcplslg123]

Re: Asus X555L backlight shuts off when on battery

Yes, its on screen itself near backlit PWM Ic. Perhaps there is marking on coil "100"

[generic1]

Re: Asus X555L backlight shuts off when on battery

Yes, its on screen itself near backlit PWM Ic. Perhaps there is marking on coil "100"

Oh good, that sounds like it's not too hard to get to. Does the new coil have to be soldered in place or does it just snap in? And do you know where I could buy replacement coils?

[mcplslg123]

Re: Asus X555L backlight shuts off when on battery

New coil has to be put with same marking. You can get same coil from another dead/broken led panel.

[generic1]

Re: Asus X555L backlight shuts off when on battery

New coil has to be put with same marking. You can get same coil from another dead/broken led panel.

Unfortunately I don't have any dead/broken panels. It may be easier for me to replace my panel entirely. Thanks for your help!

[croweye]

Re: Asus X555L backlight shuts off when on battery

its was not the coil in my case, it was from a bad cm509a next to the coil, on the lcd pcb

[shybear]

Re: Asus X555L backlight shuts off when on battery

LCD coil here too!!
I used one just marked 100 same dimension but a different plastic enclosure.
It was a bit nightmare desolder the bad one!

[Mohsen71]

Re: Asus X555L backlight shuts off when on battery

Hello Guys

Changing the "coil 100" Worked for me as well !!!
thank you so much for this awesome thread.

i wish i saw this thread sooner

[Arielc72]

Thanks for the info. I replaced the coil and it started working (operating at 34V), but after a few minutes it started to flicker, Then I replaced the diode and it kept doing the same thing. Finally I replaced the IC (CM509A) and it worked perfectly. So, the solution in my case, was replacing Coil + IC.

[caspian]

Two weeks ago, I had an Asus X555 that had no backlight when on battery. But it had steady backlight when on Charger. Then, I replaced the coil with a good one (100uH) from another screen. Then, the problem got fixed meaning that it had steady backlight when on battery.
However, the customer discovered that the backlight fluctuates when it is on battery and the battery charging level is under 50%.
What component does cause this problem?
What should I do now to fix it? Any similar experience?

[mcplslg123]

Look for corroded caps near backlit controller. If corroded,replace those caps. Last thing to try is replacing the backlit controller.

Btw, if u have spare tested battery,test it first with another one.