Author Topic: Need help identifying burnt component ASUS G751JY (Read 13606 times)

DonDeKuch · « **on:** February 25, 2015, 07:03:21 pm »

Hello everyone, I was told in the other forum that you guys are awesome and could help me finding out what component is this (see pictures). You can read OP or just check the pics! Thanks

The problem is as follows:

I took apart my G751JY down to the last bolt, however when I put it back together the screen was not working. The external monitor works but the LCD screen remains black. Tried holding the power button for 20 - 45 - 60 seconds, does not help. Tried unplugging/plugging in the screen - does not help. Took apart the screen nothing special there. Took apart the laptop again, and on the bottom of the mobo found out that a certain part was fried (see pictures)
The screen is black/does not show signs of life, however when pointed at with bright light I can pick up details.
What caused the problem? (my thought) -When taking the laptop apart i disconnected screen prior to disconnecting the battery (since the battery is internal I unhooked the LED screen connector first and only then saw the battery connector - my mistake I know).

The only problem is the LCD backlight, everything else works great - GPU,CPU, RAM, charging etc. Just the backlight does not.
I need your help to figuring out what kind of part is this and if it is possible to fix it? I know its hard to pick it out from pictures but maybe someone has seen this before. Any ideas will help! Thanks!

DonDeKuch · « **Reply #1 on:** February 25, 2015, 07:16:50 pm »

I can't say what it is for sure, since i am not really experienced in this field. However I dont think it directly connects to this part (it doesn't show in any of my pictures, but i remember it not connecting directly). This burnt part had only 2 connections with solder.

DonDeKuch · « **Reply #2 on:** February 25, 2015, 08:09:11 pm »

Yes I understand your point. What would be the best way to identify the part? Size/color.. Any ideas? Of course the motherboard manual would be the easiest way, but can't really find it..

DonDeKuch · « **Reply #3 on:** February 25, 2015, 08:32:34 pm »

No, no repair was done, this is what I found when I was troubleshooting the non working LED backlight. - everything else works (on a 2k laptop lol).

N8AUM · « **Reply #4 on:** February 25, 2015, 09:07:10 pm »

My best guess is a choke. Measure either side to ground, if very low resistance than thats what caused it to blow.
If measure couple hundred ohms or more than short it out and see if display fires up.
Good luck !

DonDeKuch · « **Reply #5 on:** February 25, 2015, 09:27:07 pm »

Hm.. I was thinking on shorting it out, but I guess it would be the last thing I would do. Didn't think it could be a choke, but it does look like this one though http://www.gmelectronic.com/smd-choke-tl-33uh-smd-1206-p965-177

But again, they all look pretty much the same capacitor/resistor and a choke.

N8AUM Could you please go through the process of measuring ohms in a more detailed manner? Since I am not very experienced in this field. And thanks.

N8AUM · « **Reply #6 on:** February 26, 2015, 12:46:34 am »

DonDeKuch, mind you without a schematic I am only GUESSING. Can you measure the resistance to ground on both sides and post your results ?
On one side the artwork shows what could have been a regulator and for what ever reason they decided to omit it and use a choke. Now if you measure zero ohms from the bottom side to ground than than my 1st guess is wrong. Can you also power it up and take some measurements ?

DonDeKuch · « **Reply #7 on:** February 26, 2015, 01:01:16 am »

Hehe I don't want to sound like a complete noob here, but I kind of am. So by asking you to tell me how to measure resistance I meant to ask you how do I exactly measure resistance to ground? I am not sure where can I find ground there. Obviously testing this part for continuity provided no continuity, and thats how far I could go with my multimeter

Trying to measure it with power on would be really problematic since this part is on the bottom of the motherboard.

N8AUM · « **Reply #8 on:** February 26, 2015, 01:36:05 am »

Quote from: DonDeKuch on February 26, 2015, 01:01:16 am

Hehe I don't want to sound like a complete noob here, but I kind of am. So by asking you to tell me how to measure resistance I meant to ask you how do I exactly measure resistance to ground? I am not sure where can I find ground there. Obviously testing this part for continuity provided no continuity, and thats how far I could go with my multimeter

Trying to measure it with power on would be really problematic since this part is on the bottom of the motherboard.

bn

N8AUM · « **Reply #9 on:** February 26, 2015, 01:39:54 am »

Quote from: N8AUM on February 26, 2015, 01:36:05 am

Quote from: DonDeKuch on February 26, 2015, 01:01:16 am
Hehe I don't want to sound like a complete noob here, but I kind of am. So by asking you to tell me how to measure resistance I meant to ask you how do I exactly measure resistance to ground? I am not sure where can I find ground there. Obviously testing this part for continuity provided no continuity, and thats how far I could go with my multimeter

Trying to measure it with power on would be really problematic since this part is on the bottom of the motherboard.
bn

Usually the ground will be the largest portion of copper. Can you take a pic showing more of the board ?

DonDeKuch · « **Reply #10 on:** February 26, 2015, 02:08:23 am »

Since i am currently using the laptop and the board is deep inside the laptop I borrowed this pic from the net. But thats the board. As i understand the ground is that copper area where the screws go?

N8AUM · « **Reply #11 on:** February 26, 2015, 02:23:40 am »

Quote from: DonDeKuch on February 26, 2015, 02:08:23 am

Since i am currently using the laptop and the board is deep inside the laptop I borrowed this pic from the net. But thats the board. As i understand the ground is that copper area where the screws go?

In most cases it will be ground but I have seen so many weird things that I learned not to say "yes" LOL
You can try the outside metal part of the VGA connector.
Oh, as far as making resistance measurements, I imagine there are tons of how to videos on utube on this.

DonDeKuch · « **Reply #12 on:** February 26, 2015, 02:28:23 am »

Ok. I'll do this tomorrow then. I will also look for the same chips on the motherboard and try to record the readings on the multimeter, which readings I should record on the same components? maybe that would help?

N8AUM · « **Reply #13 on:** February 26, 2015, 02:56:19 am »

Quote from: DonDeKuch on February 26, 2015, 02:28:23 am

Ok. I'll do this tomorrow then. I will also look for the same chips on the motherboard and try to record the readings on the multimeter, which readings I should record on the same components? maybe that would help?

If you can locate the same type of component on the board than you will know what it is.
If it turns out to be an inductor, a good one will measure virtually a short across it.

wraper · « **Reply #14 on:** February 26, 2015, 08:04:32 am »

This is inductor with a probability of 99%, not capacitor as some others are saying.

DonDeKuch · « **Reply #15 on:** February 26, 2015, 09:50:05 pm »

Took it apart again and did the measurements, got the picture from the other side of the component as well as the pictures from the other side of the motherboard.

Testing the failed component to ground showed 16.78 K ohms on one side, but unfortunately I couldn't get any reading from the other side.
Looked for similar components to this one and found somewhat same size/color components but they were all in a group and didn't have any readings when checking for resistance, had continuity. Definitely can't say they were the exact same component - also no markings on them.

The pictures taken from the other side of the motherboard shows what components are underneath this failed component, tried to check for ground got readings of 0.207 and 0.208 M ohms - not sure if this was relevant but gave it a try.

Wraper - could you please explain why do you think it is an inductor/chije? Not questioning your opinion just need more information and ideas to why did it burn and to have more understanding overall.

Thanks again for your time.

N8AUM · « **Reply #16 on:** February 27, 2015, 03:03:28 am »

just to make sure we are on the same page, the 1st 2 readings where from one side to ground than the other side to ground

other side of component, not the board.
I am assuming that you dont have an inductor handy or some scrap board that you can salvage from ?
if it was me and based on those measurements I would just short out the part with the finest piece of wire and fire it up! I use a single strand from solder wick so if there is a problem it wont take much to blow the wire.

wraper · « **Reply #17 on:** February 27, 2015, 03:22:43 am »

Quote from: DonDeKuch on February 26, 2015, 09:50:05 pm

Wraper - could you please explain why do you think it is an inductor/chije? Not questioning your opinion just need more information and ideas to why did it burn and to have more understanding overall.

Thanks again for your time.

I have yet to see ceramic capacitor in black color and tracks going to it. Fault symptoms too. Cracked ceramic capacitor on the motherboard would not cause backlight to disappear (unless shorted). There obviusly is no GND connected to this part and I see that there is a place on the PCB where altrnatively mosfet could be soldered instead of this part (to disconnect this power rail when needed).

DonDeKuch · « **Reply #18 on:** February 27, 2015, 03:30:05 am »

Yes, first I tried the component itself (only one reading was successfull), then tried the other side of the motherboard at the approximate location of the component - not 100% sure that those readings were from that component, but gave it a try.

I could look for these inductors online, however if i was gonna look for them not knowing the exact specs what would it rather be based on IDC and RDC higher or lower? Also I was looking to ask a person from the other forum to check the readings on his working exact same component. What would he need to measure to be able to know which inductor is it?

wraper · « **Reply #19 on:** February 27, 2015, 03:39:02 am »

Should be rather low inductance as it passes significant current. Exact value not so important, solder blob instead of it should work too. More important is current rating. I would solder something with 1A rating or even more to be safe. You could measure exact current to with multimeter on Amps rance connected instead of this part and brightness set to max. Then choose replacement accordingy with some safe margin.

DonDeKuch · « **Reply #20 on:** February 27, 2015, 04:02:54 am »

Ok Thanks to all of you, I'll keep you posted on my final findings and results!

DonDeKuch · « **Reply #21 on:** March 13, 2015, 03:21:27 am »

An update!

So a friend of mine (EE technician) analyzed a mobo manual of a different laptop and confirmed that it could be an inductor/ferrite bead. Therefore I order 3A ferrite beads and installed them on top of the old one and it worked!

Thanks again for all the help and guidance. You guys are awesome!!!

hal0000 · « **Reply #22 on:** April 21, 2018, 02:43:17 pm »

Quote from: wraper on February 27, 2015, 03:39:02 am

Should be rather low inductance as it passes significant current. Exact value not so important, solder blob instead of it should work too. More important is current rating. I would solder something with 1A rating or even more to be safe. You could measure exact current to with multimeter on Amps rance connected instead of this part and brightness set to max. Then choose replacement accordingy with some safe margin.

Quote from: DonDeKuch on March 13, 2015, 03:21:27 am

An update!

So a friend of mine (EE technician) analyzed a mobo manual of a different laptop and confirmed that it could be an inductor/ferrite bead. Therefore I order 3A ferrite beads and installed them on top of the old one and it worked!

Thanks again for all the help and guidance. You guys are awesome!!!

I know it's been a long time but i need help.

Hi,

I have the same laptop and same thing too my laptop working well exept screen after re-paste / fan cleaning can you help me

wraper · « **Reply #23 on:** April 21, 2018, 07:49:31 pm »

Is video output working if you attach external monitor? Is it completely not working or just no backlight?

hal0000 · « **Reply #24 on:** May 10, 2018, 04:55:38 pm »

Sorry for late answer today i got my laptop back yes it's same man working perfect with HDMI port
Here you are my pictures:

Same problem with yours.
What Should i buy ?
I have G751JT with G-SYNC


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Author Topic: Need help identifying burnt component ASUS G751JY (Read 13606 times)

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