ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

[coldfuse]

Model: UX51VZ-DH71
Motherboard: 60-NWOMB1A01-B07
WLED Screen: LP156WF4(SP)(B1)

• Description of issue: Back light for LED Screen does not receive power.
  
• What caused the issue: After fixing a no sound issue on the laptop, during reassembly, I mistakenly reconnected the battery, before reconnecting the inverter ribbon cable back to the inverter slot.
• Notable occurrences: Corners of the inverter slot, and ports on the right sparked once. I immediately unplugged the battery, and took a break.
• Functionality of product: Everything functions perfectly, aside from the Back Light.
  
• Solution: I need help identifying the fuse, confirmation or relevant knowledge reviewed and fixed and any further information that anyone could provide. So I can then commence a chip-level repair.

1. Data is still transmitted to inverter card, verified by shining a light into the screen, faint image then appears.
2. The mini-VGA port on the side that sparked functions, and allows connectivity to an external monitor, which confirms the video controller is working. Everything is functioning, including the ports that sparked and test perfectly with a multimeter.
3. Multimeter shows a fuse like object testing no continuity to the left of power supply, this could just be a capacitor, it looks identical to a fuse with no marking.
4. Power supply can be traced (1) to the inverter slot, through capacitor -> four prong SMD fuse with O marking -> Inverter slot.
5. The four prong object which I believe to be the SMD fuse for the inverter card power, registers .1 @ 200ohm reading and all other readings, unless I test the fuse using 1 prong per side of fuse diagonally, then registers 1. This could just be a four-prong power relay.
6. Unable to find any identifiers for the fuse, that indicate the product number of the fuse or the rating.
7. Unable to get support or any schematics from ASUS or abroad, as of yet.
8. I have not solder balled anything, or attempted to bypass anything in fear of further damage or incorrect knowledge.
9. I have identified the power fuse (F1) built on the inverter card and another (F2), both test continuity but F1 doesn't read at meter rating, it registers .2 but the F2 registers .1 as it should. I am not sure if this will nullify the need to have a fuse for the inverter on the motherboard? Please let me know.

I would greatly appreciate any support that could be provided, as my product is no longer under warranty and ASUS won't budge for any information. I can't afford to replace this specific motherboard, and I can't even find one that matches my specs or model number, I've even checked manufacture and export databases. As you can see, I have provided imagery of the board for further assistance in examining the product the last two images are of the screen inverter board. I could use further tips on correct testing.

Thank you, - J.S.

[budm]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

https://www.badcaps.net/forum/attach...2&d=1424060681

That brown rectangular component next to F2 is capacitor MLCC (Mutil Layer Ceramic Capacitor).
So that FUSE F2 (1.5A with 63V minimum Voltage rating) does not show continuity <1 Ohm?
F1 is 1.5A with 32V rating.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Ahh okay, I appreciate the correction. As a correction to my image I posted, it does not register anything when testing using OHM 200.

As for Fuse F2, it does not show continuity above 1 ohm. Only .1 @ 200 setting.
As for Fuse F1, it registers .2 @ 200 setting.
I just fixed my posts with the readings I'm getting, as I put the wrong information up originally.

[budm]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Ahh okay, I appreciate the correction. As a correction to my image I posted, it does not register anything when testing using OHM 200.

As for Fuse F2, it does not show continuity above 1 ohm. Only .1 @ 200 setting.
As for Fuse F1, it registers .2 @ 200 setting.
I just fixed my posts with the readings I'm getting, as I put the wrong information up originally.

I do not understand as to what you mean the fuses does not show continuity above ohm, only 0.1 @ 200 setting, so it shows 0.1 Ohms on 200 Ohms scale then it is good. May be I am not reading your explanation correctly.
Or you are saying that it does not show anything, then it is bad, that is what sounds to me with your explanation.
If that is the case, then check the resistance of that brown cap next to F2 to see what it shows.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

From what I understand if something reads 1 and is a fuse, then it is bad. But if it reads .(something) it is good if it reads back what the ohm reading is when you touch the two leads together. Please correct me if I am wrong. I am using this multimeter.
Fuse F2 does test .1 on the 200 OHMs scale. So this is a good fuse? What about F1 if it registers .2? The brown cap doesn't read anything, it just sits at 1.

Using my fluke leads on my MAS830B, I'm getting .4 on Fuse F1 and .3 on Fuse F2. I'm not using my Fluke multimeter because it's extremely sensitive and jumps around when touching the leads together instead of settling and my readings bounce back and forth. My readings on the Fluke changes if my hand just shakes for a second lol. It's also giving me different readings when testing the capacitor, which of course it would considering it's far more accurate than my cheap Homedepot mm.



I can also test using this meter, but I am less familiar with it:

[newtothis]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

If the fuses were open they would read 1. 0.2 means it is still allowing a connection so it is therefore closed and good. A fuse will only read open or closed as there is nothing else to them

[newtothis]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

If you can trace the route of power as you stated in your original post... have you not gone over that route when powering the system to see where the power stops?

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Ahh, I see. So, the issue must be an isolated one on the motherboard. Just because there are fuses on the inverter board attached to the screen, does that nullify the need to put a fuse on the motherboard between the power supply and the inverter board?

If there is a chance, can someone help me identify where it is on the mobo or what is causing this issue?

I didn't trace it using my multimeter, I just took a look at the markings on the board and got a generalized idea of what the route was, I'm not even sure if the components I listed in the route are correct, in terms of component names. The reason for this is because I'm not familiar enough to do such a task without fear of harming my components. I'll be spending my time reading for a bit and then have at it, if you have any tips for me on tracing the power route, let me know as I could use some assistance in going about this.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Alright, here's an update. I just spent about roughly 4 hours reading and replicating tests that were used in diagrams, logging some real experience at the same time which I plan on putting a lot more time into. I was off quite a bit on what I thought I knew, I guess I just trusted the person who briefed me a bit too much on this subject than I should have. So, I will continue to update this thread throughout my journey.

I'm now using my Fluke 78 MM and I have to say, it's so much better than my cheap MM. It is an Automotive Meter but hey, it has everything I need on it except the mA, I need the RMS for that, I might have one laying around here somewhere, but I don't really need it for this task as the LED takes operates with 1.5A 63V/min.

newtothis, do I have to power the system? Can't I just do a continuity test to see if somewhere the circuit breaks, which it is somewhere between the supply to the inverter board, but I believe I've taken the inverter board out of the picture, so that leaves us with it being isolated on the board? I mean, I would only power on the system to measure Volts & Amps flowing through, but we already know what should be flowing through, so a continuity test should identify where the break is in the circuit, unless not enough power is going to the inverter board, but I'm sure no power is going to it at all.

You know, if I had schematics this would be so much easier. I could just print it out and make hard notes, using it as a reference as well. Apparently only ASUS technicians are allowed to handle the schematics. Can anyone give me advice on how to pressure them to give me the schematics or how to go about obtaining them from maybe their patent registration?

[newtothis]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Unfortunately it is not as simple as just checking continuity.

Components react differently to different voltages for EG and if something is shorted closed when it should be open the system will malfunction. Say a component had Source Drain and Gate and it is getting a constant power supply at the gate when it shouldn't due to a component being shorted open earlier in the circuit then the power route is already now wrong.

Hope you understand as I am trying to explain as easily as I can.

Budm may be able to help you further but troubleshooting such circuits is incredibly hard! Sometimes simple switching PSU's are bad enough!

[budm]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

OK, instead of checking the continuity of the fuses, you should check and see if both ends of the fuses have DC voltages using the black probe of the meter on the chassis ground, you will have to have the unit on, and make sure you do not let the probes slip on you.
BTW, the 1.5A/63V is the rating of the fuse not the Voltage or current rating of the circuit.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

I see, well I will have to try this sometime next week as I have to order a new screen. When removing the screen, the adhesive between the frame and screen was so strong, that upon sliding a card between the frame and screen, to break the bond of the adhesive, part of the screen ripped up with the adhesive. Is it still possible to run these tests in the event that has happened?

I appreciate the extra info. Worse comes to worse, I now have a screen with an inverter card that I can test with without the fear of destroying it lol and I'll now be able to completely rule out if it is the screen or not upon replacing it.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Update:

F1: Top/3.27-3.29vDC Bot/3.23-3.29vDC
F2: 0/0vDC Both bridged and unbridged

There we have it, no power is passing through F2, which is for the WLED, even when bridged.
Something to note since the screen has cracked, I no longer see the screen when shining a light at it. I don't think this would matter, but just a note.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Budm, new, the screen has been replaced (which got me a new inverter board, as well) and the problem still persists. I need to start identifying parts on the MOBO. Can you look at my MOBO pictures and help me identify the parts? I'm hoping the faulty part will be in the vicinity of the inverter slot, though I have seen some boards that have faulty parts that effect the circuit to the backlight all the way across the MOBO. Thank you, -J

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Here we go! Now I just need to identify this here component!

Is this an SMD Ferrite Bead/Inductor/Choke? Someone that is having a identical cause and issue on an ASUS ROG claims theirs is an SMD Ferrite Bead.

I have included two images of identification markings for the PCB and one image showing the blown obliterated component.

[budm]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Check resistance:
between Point 'A' and Point 'B'
between Point 'A' and GND
between Point 'B' and GND

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Check resistance:
between Point 'A' and Point 'B'
between Point 'A' and GND
between Point 'B' and GND

On the component? My brother went in there to bypass it using some wiring and when he went to heat up the contact points the component sucked right up into the tip & since the component is so low down to the board the heat coming off from the tip of the gun was causing the board to bubble up. Such a touchy task.

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

Well, I am looking for a 0603/1.6x0.8mm Surface Mount Multilayer Ferrite Bead. Not sure of the rating. I'm thinking 1.5A (correct me if I'm wrong) based on what I saw marked next to the fuse for the backlight built into the screen. The webcam, and mic both run on the same ribbon as the ribbon to inverter card, therefor we can assume the pins for the led backlight for the screen are on a separate inductor considering everything else is working fine. I would definitely send some complaints to the manufacturer if they weren't.

However, I am having trouble finding one that matches the rating I suspect. Could anyone assist me? I've been looking all over the place; Digikey, and a few other places but can only find them directly from the manufacturers where they can only be bought in bulk.

Thanks, J

[budm]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

http://www.digikey.com/product-detai...3-1-ND/1639537

[coldfuse]

Re: ASUS UX51VZ-DH71 - Back Light SMD Fuse Identification

http://www.digikey.com/product-detai...3-1-ND/1639537

You're absolutely sure? What will happen if I needed a 1.5A and this is a 1A, is it going to blow up or something? Should I order some 1.5As as well? There was a guy with the same issue as me that ended up replacing his with a 3A. It was an ASUS Rog series gaming laptop though.

Thank you, -J