Backlight failed, only shows with hard light please help :)

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MacBook Pro 13" Unibody Early 2011

Early 2011 Model: A1278 / 2.3 GHz i5 or 2.7 GHz i7 processor

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Nathan Pelling @nathanpelling

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Postado: 8 de mar de 2017

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Backlight failed, only shows with hard light please help :)

Hi guys I have,

Macbook pro 2011 late 13" laptop.

I can only see the screen with hard light from the back of the screen.

Tried resetting pram SMC, deleting PLIST login file, still no joy.

Im thinking of changing the Backlight fuse & WLED driver.

Where are they located on the 820-2936 B motherboard ?

There also seems to be a little bit of burning on the LVCDS connector ?

Have a look at my pictures theres a crack on a chip and I dont know if it will be causing a short as I dont know which component it is.

Any help is appreciated. I have SMD re work station and know a fair level of electronics.

I have this for the logic board now so will be easier to locate chips etc.

updated multi meter resistance reading.

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Reece @reecee

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eFix Ltd (UK)

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Postado: 8 de mar de 2017

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Firstly, don't change stuff without taking readings beforehand, you will likely just be wasting your time.

Measure the side of the capacitor I have pointed to in your picture, and tell me the voltage. If you are not getting a voltage at all, check for a short to ground. This is for the backlight voltage. The LCD connector looks slightly melted above this capacitor (might just be the picture), check the cable to make sure the pins are not bent, and there is no missing plastic. Shine a light inside the LCD connector too, if it looks a bit melted/burnt, the connector is shorted and will need to be replaced.

The chip with the cracked casing nearly always cracks, it is for ethernet and will be fine. Let me know how this goes.

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Ive measured the resisitor you pointed out mate. My multimeter is fairly old and is giving ( .609v with red probe to ground & black probe touching the left side of resistor ) Working on diode mode auto range. Right side of that resistor give beep.

Looked inside the LVDS it visually looks ok.

13 de mar de 2017 por Nathan Pelling

I did this with no power to board.

13 de mar de 2017 por Nathan Pelling

You need to measure the side pointed out in the picture with voltage running through it. If it has .6V with voltage running through (and the screen plugged in), check for a short on this side. The right side will beep since it is ground.

13 de mar de 2017 por Reece

Will this be a safe voltage with charger connected to MagSafe while taking readings off board ?

14 de mar de 2017 por Nathan Pelling

Yes, as long as you are not measuring continuity across one component, or short different components together. You need to run voltage through it to measure the voltage

14 de mar de 2017 por Reece

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Ive measured the resisitor you pointed out mate. My multimeter is fairly old and is giving ( .609v with red probe to ground & black probe touching the left side of resistor ) Working on diode mode auto range. Right side of that resistor give beep.

Looked inside the LVDS it visually looks ok. — Nathan Pelling
You need to measure the side pointed out in the picture with voltage running through it. If it has .6V with voltage running through (and the screen plugged in), check for a short on this side. The right side will beep since it is ground. — Reece
Will this be a safe voltage with charger connected to MagSafe while taking readings off board ? — Nathan Pelling
Yes, as long as you are not measuring continuity across one component, or short different components together. You need to run voltage through it to measure the voltage — Reece

Gigabit87898 @gigabit87898 Rep: 16,1 mil 39 92 13 · Answer 1 · 2017-03-08T12:49:51-07:00

Gigabit87898 @gigabit87898

Rep: 16,1 mil

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Postado: 8 de mar de 2017

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If you are talking about the big chip directly below the lvds connector, that is something for ethernet. Test the fuse for continuity and if it gives the correct voltage on one line but not the other.

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