Re-solder U8900 in MacBook Pro 15in Mid 2012/Early 2013 - fixes common black screen and/or kernal panic issue
This is a repair service that is performed on our premises. Once booked you will need to either bring or send your machine into us, or you can have us send our courier to collect it - see here. Once complete you can collect the machine from us, or we can ship it back to you for our standard courier delivery charge (applied during the checkout process).
This repair service is for the MacBook Pro Retina 15in Mid 2012 and Early 2013 machines only, and fixes a common problem on these machines by resoldering the U8900 GMUX chip.
Internal display goes black during operation, with the machine often remaining running underneath (eg keyboard remains lit). Some machines will see a more severe crash, and fans may ramp up to full.
Kernel Panic which mentions AppleMuxControl - see image below.
Sometimes gently bending the machine's bottom case will cause the display to come back.
What Causes it?
This is a common problem on this model of machine (specifically, machines with logic board part number: 820-3332). It is often, and incorrectly, diagnosed as a problem with the GPU itself. Actually the issue is with the chip which provides power for the GPU or GPU_VCORE.
The chip is located on the underside of the logic board, and has a CPU heatsink screw hole above it. This produces tension in the board, and along with poor factory soldering causes connection issues between the board and the chip, especially when hot.
What is the Fix?
The fault can be fixed by removing the logic board, and removing the bad lead free solder, and redoing with good leaded solder and flux whilst the board is hot around all the pins of the U8900 chip. This remakes the connections and allows normal operation. Unfortunately nothing can be done about the location of the chip, so the tension in the board may cause a recurrence at some point in the future.
What this will not Fix
Faults with the actual GPU - typically symptoms of this would involve graphical artefacfts on the display.
A typical kernel panic caused by a U8900 fault. Note the mention of AppleMuxControl.
Before and after images of the U8900 repair.
Below is a list of compatible Macs for this item. You can click on any of the pictures to see the precise models it covers. We guarantee full compatibility with all models covered by each link, subject to any exceptions explicitly listed below.
MacBook Pro Retina "Function Keys"
- This fault is unique to the 15" models from Mid 2012 and Early 2013.
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