Need help identifying burnt component ASUS G751JY - Page 1
Forum section: electronics / repair

author: DonDeKuch
author_rank: Contributor
timestamp: February 25, 2015, 07:03:21 pm
content: 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! ThanksThe 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!

author: DonDeKuch
author_rank: Contributor
timestamp: February 25, 2015, 07:16:50 pm
content: 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.

author: DonDeKuch
author_rank: Contributor
timestamp: February 25, 2015, 08:09:11 pm
content: 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..

author: DonDeKuch
author_rank: Contributor
timestamp: February 25, 2015, 08:32:34 pm
content: 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).

author: N8AUM
author_rank: Regular Contributor
timestamp: February 25, 2015, 09:07:10 pm
content: 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 !

author: DonDeKuch
author_rank: Contributor
timestamp: February 25, 2015, 09:27:07 pm
content: 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 thoughhttp://www.gmelectronic.com/smd-choke-tl-33uh-smd-1206-p965-177But 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.

author: N8AUM
author_rank: Regular Contributor
timestamp: February 26, 2015, 12:46:34 am
content: 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 ?

author: DonDeKuch
author_rank: Contributor
timestamp: February 26, 2015, 01:01:16 am
content: 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 multimeterTrying to measure it with power on would be really problematic since this part is on the bottom of the motherboard.

author: N8AUM
author_rank: Regular Contributor
timestamp: February 26, 2015, 01:36:05 am
content: Quote from: DonDeKuch on February 26, 2015, 01:01:16 ambn

author: N8AUM
author_rank: Regular Contributor
timestamp: February 26, 2015, 01:39:54 am
content: Quote from: N8AUM on February 26, 2015, 01:36:05 amUsually the ground will be the largest portion of copper. Can you take a pic showing more of the board ?

author: DonDeKuch
author_rank: Contributor
timestamp: February 26, 2015, 02:08:23 am
content: 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?

author: N8AUM
author_rank: Regular Contributor
timestamp: February 26, 2015, 02:23:40 am
content: Quote from: DonDeKuch on February 26, 2015, 02:08:23 amIn most cases it will be ground but I have seen so many weird things that I learned not to say "yes" LOLYou 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.

author: DonDeKuch
author_rank: Contributor
timestamp: February 26, 2015, 02:28:23 am
content: 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?

author: N8AUM
author_rank: Regular Contributor
timestamp: February 26, 2015, 02:56:19 am
content: Quote from: DonDeKuch on February 26, 2015, 02:28:23 amIf 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.

author: wraper
author_rank: Unknown
timestamp: February 26, 2015, 08:04:32 am
content: This is inductor with a probability of 99%, not capacitor as some others are saying.

author: DonDeKuch
author_rank: Contributor
timestamp: February 26, 2015, 09:50:05 pm
content: 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.

author: N8AUM
author_rank: Regular Contributor
timestamp: February 27, 2015, 03:03:28 am
content: 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 groundother 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.

author: wraper
author_rank: Unknown
timestamp: February 27, 2015, 03:22:43 am
content: Quote from: DonDeKuch on February 26, 2015, 09:50:05 pmI 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).

author: DonDeKuch
author_rank: Contributor
timestamp: February 27, 2015, 03:30:05 am
content: 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?

author: wraper
author_rank: Unknown
timestamp: February 27, 2015, 03:39:02 am
content: 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.

author: DonDeKuch
author_rank: Contributor
timestamp: February 27, 2015, 04:02:54 am
content: Ok Thanks to all of you, I'll keep you posted on my final findings and results!

author: DonDeKuch
author_rank: Contributor
timestamp: March 13, 2015, 03:21:27 am
content: 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!!!

author: hal0000
author_rank: Newbie
timestamp: April 21, 2018, 02:43:17 pm
content: Quote from: wraper on February 27, 2015, 03:39:02 amQuote from: DonDeKuch on March 13, 2015, 03:21:27 amI 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

author: wraper
author_rank: Unknown
timestamp: April 21, 2018, 07:49:31 pm
content: Is video output working if you attach external monitor? Is it completely not working or just no backlight?

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 04:55:38 pm
content: Sorry for late answer today i got my laptop back yes it's same man working perfect with HDMI portHere you are my pictures:Same problem with yours.What Should i buy ?I have G751JT with G-SYNC

author: wraper
author_rank: Unknown
timestamp: May 10, 2018, 08:07:11 pm
content: It's a ferrite bead. For starters you could just short it with a piece of wire and see if it works. Also would be worth to check if there is no short to ground. It everything works, then you can either buy some ferrite bead of correct size and at least 3A current rating. Or leave as is, it won't affect functionality.

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 08:42:53 pm
content: Quote from: wraper on May 10, 2018, 08:07:11 pmI don't think there is short something else because of everything else is fully functional so you saying use 3A and ohm is not important ?and if i just remove that Ferrite Bead with screw and leave it ? or soldering ?And if i use my laptop like that does it hurt something else ?

author: wraper
author_rank: Unknown
timestamp: May 10, 2018, 10:00:40 pm
content: It's there for some noise suppression. Actual value is not critical. There is no other way to know original value other than finding the schematic.QuoteDon't understand what you mean. Just desolder it and short the pads with a piece of wire to check if everything else is fine.

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 10:03:49 pm
content: Quote from: wraper on May 10, 2018, 10:00:40 pmI will desolder and short the pads like 7 days later but i must buy ferrite bead just incase so 3A and 1608MM is enough ? or Ohm is important too ?30+25% to what ? can i use 70 ohm too ?

author: wraper
author_rank: Unknown
timestamp: May 10, 2018, 10:13:30 pm
content: You basically can use any rating as long as current spec is high enough.

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 10:16:19 pm
content: Quote from: wraper on May 10, 2018, 10:13:30 pmThis Ferrite Beads is really hard to find in my country and shipping from other countries is non sense shipment prices like 25-75 €so as long as higher then current specs is everthing is okay ?

author: wraper
author_rank: Unknown
timestamp: May 10, 2018, 10:21:05 pm
content: Yes. if it is hard to source, just short the pads together and leave like that. You could look on ebay or aliexpress. It will be more economical to buy a single part there.

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 10:23:20 pm
content: Quote from: wraper on May 10, 2018, 10:21:05 pmSorry for being and amateur but "short the pads" you mean desolder the broken beads and leave it like that ? or solder with wire ?

author: wraper
author_rank: Unknown
timestamp: May 10, 2018, 10:24:43 pm
content: Quote from: hal0000 on May 10, 2018, 10:23:20 pm

author: hal0000
author_rank: Newbie
timestamp: May 10, 2018, 10:27:00 pm
content: Quote from: wraper on May 10, 2018, 10:24:43 pmsolder with wire indeedThanks man i can only try on next week. I will update this thread when i did the solution.

author: hal0000
author_rank: Newbie
timestamp: May 11, 2018, 09:55:29 am
content: I purchased this:Wurth Elektronik Ferrite Bead (EMI Suppression), 1.6 x 0.8 x 0.8mm (0603 (1608M)), 30Ω impedance at 100 MHzDATASHEET PDF:http://pdl.designspark.com/api/v1/manufacturers/53f321fc9b4759f8699d4316/part/53f3300d9b4759f869bb2d9f/5491d8489b47599b72937df5/1pdf

author: wraper
author_rank: Unknown
timestamp: May 11, 2018, 10:21:21 am
content: should do the job