Asus R505CB (K56CM motherboard) backlight problem

[Modelvincent]

Hi guys,

I have a problem with my Asus R505 laptop, my screen wires are damaged since some days (bad contacts when moving the screen...) so I was no more using ma laptop waiting to receive the new cable.

Unfortunately yesterday I have restarted it to connect the display to my TV but no display on TV nor than on the computer screen.

I've move the screen and heard the so characteristics noise and smell of the burning electronic component (you know, the little "pschiiiiiittttt"....

I've removed the charger, the battery, and opened the PC and found the problem: a diode (or what looks like) on the backlight inverter is burned... it seems to be the only burned part, I suppose that the backlight wires were damaged inside the cable and have done a short-circuit...


My problem is that now I'm no more able to read the reference of this component, and before to replace it by a standard shottky diode I prefer to try to find someone able to give me the correct reference...

So my question: Can someone tell me the reference of the component burned on the photo:



For information it is under the motherboard, there is a black sticker over all the back of this side, and the component is located just under the screen connector.

Thanks in advance for your help !

Best regards

Modelvincent

[atsio]

Re: Asus R505CB (K56CM motherboard) backlight problem

Take a closer photo and also another of the whole of the board pointing the burned ic.

[meritosari]

Re: Asus R505CB (K56CM motherboard) backlight problem

link image HD quality:

http://rusfolder.com/40254693

[atsio]

Re: Asus R505CB (K56CM motherboard) backlight problem

That's a coil. Probably you will need one 70Ohm/100Mhz

[Modelvincent]

Re: Asus R505CB (K56CM motherboard) backlight problem

Thank you both for your help,

It look evident on your picture that it is effectively not a diode and I better understand if it is a coil why she had burned on a shortcut...

I've put the copy of your picture with the component localized.


For information, does someone have the schematics of the K56CM Rev2.0 motherboard?

Thanks for your help!

Best regards,

Modelvincent

[atsio]

Re: Asus R505CB (K56CM motherboard) backlight problem

There is no schematic. Only boardview, but this area is different in boardview from the photo. My suggestion is from similar Asus schematic. Before you solder a new one check resistance on pads for shorts.

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

its a coil , you can simply makng a bypass to it , i advise to add another coil even if the Hr are bit diferent ..

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

btw anyone can share the boardview sinec there is no schematic , need to find out pins for backlight

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

or if someone only want to post the LVDS socket diagram i will be happy

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

or at least backlight enable pins backlight control , all controls for brightness .

[Doell_60]

Re: Asus R505CB (K56CM motherboard) backlight problem

I Have the exact same MBoard on my bench, it's a coil that is burned there.

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

coil burned ? for backlight ? well seeing her seems all fine without burning around , and it your case , its the 19 volts coils , my problem is the backlight controls or whatsoever

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

anyone have the LVDS socket pinout ? still have this one here stoped , there is no bacjklight .

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

if anyone have one on the bench , please share pinout voltages on the lvds socket .

thk in advance

[meritosari]

Re: Asus R505CB (K56CM motherboard) backlight problem

try this the boardview

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

thk for boardview , got no bklight control and bklight enable

[highpulse]

Re: Asus R505CB (K56CM motherboard) backlight problem

ok it might get handy to some of you , backlight problems usually due to bad LED_VCC_INV

this is due to bad resistor near (R4609) one side is AC bat sys 19 volts and outher side is the ledvcc inv , and if you notice you will see around 1 to 3 volts in my case was around 1.69 when it should be 19 , cheking resistor it says 000 (meaning short resistor , or 0 ohm ) so it should not have any kind of resistance , replacng it with a 0 ohm resistor , made the machine working , also notice that +5vcam , also need to be replace since you're gonna test it and notice there is no continuity in this 0 ohm resistor .

hope it help someone in the future

location of the resistor is bottom side of board , near the place were the lvds socket is but on oposite side . with bdv is easy to find net names and chek wich one im speaking but if you look carefully you will notice 2 resistors with 000 or 0 , and they should make continuity if not then replace

[BangBusDriver]

Re: Asus R505CB (K56CM motherboard) backlight problem

I just received one of these boards for repair.

Has no power, allegedly, but on close inspection of the LVDS connector I noticed that the right side of the connector, looking with pin 1 on facing towards me, seems to have melted. I haven't plugged it in yet, but I'm hoping I did not get ripped off.

I digress, I'm also measuring continuity and low resistance both ways across a lot of the diodes on this board.

I will post my results in this thread for those of you whom are interested.

[Sukhvinder]

Re: Asus R505CB (K56CM motherboard) backlight problem

does anybody have the schematic for Asus R505 - K56CM my Laptop turns off after few mins, the cpu is not heating

[Kiop]

Re: Asus R505CB (K56CM motherboard) backlight problem

ok it might get handy to some of you , backlight problems usually due to bad LED_VCC_INV

this is due to bad resistor near (R4609) one side is AC bat sys 19 volts and outher side is the ledvcc inv , and if you notice you will see around 1 to 3 volts in my case was around 1.69 when it should be 19 , cheking resistor it says 000 (meaning short resistor , or 0 ohm ) so it should not have any kind of resistance , replacng it with a 0 ohm resistor , made the machine working , also notice that +5vcam , also need to be replace since you're gonna test it and notice there is no continuity in this 0 ohm resistor .

hope it help someone in the future

location of the resistor is bottom side of board , near the place were the lvds socket is but on oposite side . with bdv is easy to find net names and chek wich one im speaking but if you look carefully you will notice 2 resistors with 000 or 0 , and they should make continuity if not then replace

Thanks it was exactly that , i didn't understand what was the problem voltage was there coil was fine , thought it was something about the mobo doesn't let the LCD turn on and it was the resistor you were talking about ...