Chosen Solution

Hi all. I’m quite new at trying to troubleshoot logic boards, and have very little knowledge, but I’m trying to learn. So, I received a MBP 13” Early 2011. I don’t even know the conditions of the battery as it’s clearly drained and it won’t charge. If I disconnect the battery, keep the power button pushed, connect charger, connect battery, release and push again the power button, the machine turns on, the display as well (white screen, no apple no nothing, chimes, fans spinning like crazy and that’s it. Reset SMC, machine dead again. Repeating the procedure and resetting PRAM after the chime also leads nowhere. I removed the board. Upon connection of a magsafe (Apple original 85W), the light is green for some seconds, then goes off, then returns green and so on looping. Fans: same behaviour. When the green light appears, fans spin. Then they stop spinning (and the green llight goes off) and so on forever. Following Louis Rossman’s videos and reading a few forums I started taking some measures, and here they are: F6905 - 16.8V U6900 Pin 1 - SMC_BC_ACOK_VCC - reads 3.48Pin 4 - SYS_ONEWIRE - reads 2.91Pin 5 - ADAPTER_SENSE - reads 2.90 U6901 Pin 1 - SMC_BC_ACOK - reads 2.36Pin 2 - SMC_BC_ACOK - reads 2.36Pin 4 - SMC_BC_ACOK_VCC - reads 3.48Pin 5 - PP3V42_G3H - reads 3.48C6908 - Pin 1 - PP3V42_G3H - reads 3.47 U7000 Pin 2 - CHGR_DCIN - reads 16.5Pin 3 - CHGR_ACIN - reads 3.9 L7030’s reading goes up and down from 12.5 to 3.4, continuously I then started taking some measures of a bunch of resistors and really got puzzled. I’ll explain why. R7012 - 0.99 (should be 1) R7010 - 28,3 (should be 30.1) R7011 - 9.22 (should be 9.31) R7013 - missing (should be 1) R7015 - 100.2 (should be 100) The issue here is the missing R7013. On the schematic there’s a row of 8 components (caps and res), but on the board… instead of said resistor I find two spots, and no trace of solder. It’s not the only case. R7002 seems to be missing as well, and R5011 too. It actually looks as if they were never there so I’m really puzzled. Here are a pic and a screen of the schematic.

Any help is really appreciated.

So lets go through the diagnostic process: Phase-1: What is the symptoms the customer is encountering. What happened to the system just before the failure and and additional background like liquid spills or alterations (RAM or Storage). Review the MagSafe charger being used is it a real Apple charger OEM MagSafe Chargers vs Cheap Imposters: Teardown for Truth & Real vs Fake Magsafe 2 Charger Macbook Pro is the cord and the connector in good shape? Apple Portables: Troubleshooting MagSafe adapters Also make sure its the correct wattage for the system. What is the color of the MagSafe LED a bright Amber or Green? Is the LED a dim Green? If you have any question on the MagSafe try a known good unit {FYI: I have five different units just for testing). You could also get a good power supply and take a MagSafe power cord wired up for testing. But thats mostly useful after you’ve taken the board out. Phase-2: Inspection & basic clean - Inspect the MagSafe connector on the system (DC-In board)are the pins clean and shiny? Pop the bottom cover off, do you see any staining or wet areas, is there a lot of dust on the backside of the cover and the logic board. Use a 1” soft paint natural brush to scrub the surfaces to loosen the dust and dirt, use can’ed or compressed (oil-less) air to blow out the dust (don’t forget the fans) use care not to over power the fans (short blasts). Do you see any damaged components? Look for corrosion or off color solder joints. If nothing is visible at this point fully remove the logic board to inspect the other side. Again, look for staining on the uppercase (liquid seepage) dust off the board, look for damaged components. Make note of areas impacted. Remount logic board and cables (not the battery). If needed replace the DC-Inboard before mounting logic board. Phase-3: Power - With the battery disconnected connect the MagSafe charger. Did the system boot up? What is the color of the MagSafe (it should be Amber). Did the Fan startup? So what did you find following this process? At this point you should have an idea where you need to focus in on. Given the age of the system the battery will likely need replacing but without having a working system it’s not possible to test. You could create a power extension cable so you could leverage another working MacBook Pro as a test bed. This could be useful if you plan to work on a lot of this series. From what you’ve described I would focus on the power logic. Focus on the MOSFET’s first, did you test them? Is the voltage on the power rails correct? If they are correct then you know what the issue is don’t you ;-}