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View Full Version : No backlight LED from G750JW screen caused by spark/fried chip!



roryh86
06-03-2015, 11:19 PM
Hi guys, I'll try to keep this brief as possible. I was recently cleaning out the fans and replacing the thermal paste on my G750JW CPU. While I was reassembling it and connecting the screen's LVDS cable to the connector on the motherboard, it made a strong spark.

When I turned on the laptop the screen wasnt working, but I noticed that if shined a light against the screen I could see the desktop. So the problem is my backlight LED isn't working. I tried a new screen replacement and its the same problem. So I took a look at the motherboard and noticed on the underside of the motherboard, directly under the 2D display connector there's a burnt out chip.

Does anyone know if this is replaceable and can be done at home with basic soldering without sending this to ASUS or replacing the whole motherboard?! If so, what's the name of this part that's burnt out.

Below are some photos to clear things up. I appreciate any help! Thanks.

Upper side of motherboard, display connector

49629

Underside of motherboard

49630

49632

49631

49633

49634

VengefulAncient
02-10-2016, 08:34 PM
I am curious, have you ever managed to solve this problem? I have exactly the same issue (and exactly the same cause, damn my hands and my stupidity, not having unplugged the battery for cleaning!) with my Asus N550JV. Finding schematics that would tell me what sort of component (fuse, capacitor, resistor, diode?) it is has proven impossible, and I really don't want to get a new motherboard just for this, since the rest of the laptop luckily works 100% fine (including the screen sans backlight)...

mintys1
02-14-2016, 12:01 PM
Always disconnect the battery and when necessary use a static electricity wrist band, or other device to reduce static.......could save you hundreds in the long run.

VengefulAncient
02-28-2016, 04:04 PM
Update: managed to figure the schematics out (the application is a mess, wouldn't show me the information until I zoomed in all the way to the component). Looks like in my case it's an SMD ferrite inductor (3A/120 Ohm/190 Henry/100 Hz/0603 series, originally manufactured by MaxEcho but other makes should be fine). Ordering 500 of these (because they don't sell them individually :D at least it's only $7) and a fine-tip soldering iron, I'll report on progress. OP, your burned out part also looks like an SMD ferrite inductor but I can't guarantee it's the same spec, you'll have to acquire schematics for your particular laptop to confirm that. Agree with mintys1's comment completely, but hindsight is always 20/20... at the very least it confirms the trend - everyone who has had this issue with an Asus laptop owes it to the battery not being disconnected, and there are reports of successful fixes. That's hope right there!

VengefulAncient
05-13-2016, 12:29 PM
I am pleased to report that my repair have worked out after all! All you need is steady hands, pincers (non-magnetic if you want to save your nerves), and a soldering iron with a fine tip. (Naturally, you also need to find a schematic for your laptop's board - I paid $5 for mine - and identify/purchase the replacement component; normally they're sold in big batches but rather cheap, $5-15.) Nothing else got damaged by the spark, just this one SMD inductor. Now I just need a new hinge cover and my N550 is as good as new! :) So if anyone else reads this: don't despair, you don't need to drop hundreds of dollars on a new motherboard if you're willing to try and replace the burnt component. Good luck!

nemerdekel
05-13-2016, 04:34 PM
Good job