Late 2011 model, A1278 / 2.4 GHz i5 or 2.8 GHz i7 processor.

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MacBook can not turn on, no green light on the charger (820-2936-B)

Hi,

Last week I tried to upgrade my MacBook pro 13' late 2011, yet screw touched battery jack and possibly burned the logic board. Now it can not turn on, and there is no green light on the charger.

I started to learn the board repair several days ago. Below is what I have now:

with only dc pluged:

1. PP3V42_G3H - 3.49v (is it too high?)

2. PPBUS_G3H - 0.16v

3. PPDCIN_G3H - 16.69v (is it too low? actually my J6900 pin1 (PP18V5_DCIN_FUSE) is the same reading)

4. SMC_BC_ACOK - 0v

5. SMC_RESET_L - 3.45v

6. R7010 pin2 - 4V

7. R7021 & R7022 - 10 ohm

8. Q7085 pin5 - 0v

when only battery pluged:

1. PP3V42_G3H - 3.49v

2. PPBUS_G3H - 12.23v

4. SMC_BC_ACOK - 0v

5. SMC_RESET_L - 3.45v

What do you think causes the problem? Do I need to change dc-in board, or U7000, or both? Is there any other possibility leads to the dead mac?

Thanks for your answering!

Update (01/16/2018)

Hi, I am back again. This time both good news and bad news.

First the resistance is back to normal - I measured 2.9 ohms between pin 17 and 18 after I changed the resistor. Second I changed the ISL6259. Visual inspection looks quite good.

After I plugged in the charger, the green light turns on but the fan did not spin. So I measured again the PPBUS_G3h - more than 16V! After some time the whole board dead again with no green light.

Later I detected a short on PPBUS_G3h and after some digging, it's the shorted Q7030 and Q7035. I now know the previous Q7030 is shorted. When I took off both transistors, the short is gone.

However, the bad news is I accidently ripped off the pin23 of U7000. The picture is attached. I am going to change Q7030, Q7035 and ISL6259 at the same time, but I have no idea how to connect pin23 to the board. Perhaps jumper wire? I have no confidence to do that. Any better suggestions?

Thanks in advance.

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Resposta Mais Útil

Your issue is most likely U7000 R7051 and 52 and possibly R7021 and 22. What is resistance between Pins 17/18 and 27/28 or U7000?

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I measured resistance between C7020 (equivalent Pins 27/28) is 20.2 ohm. Resistance between C7050 (equivalent Pins 17/18) is 44.8 ohm.

In addition, could you enlighten me why my PPDCIN_G3H is so low? Perhaps adapter or DC-in board?

Thank you very much!

por

1. PP3V42_G3H - 3.49v (is it too high?) No. That is fine.

2. PPBUS_G3H - 0.16v -- Should be 12.56. 44 ohms is WAY TOO HIGH for pins 17 and 18. Should be 2 ohms but up to 5 is fine. Replace R7051 and R7052.

3. 3. PPDCIN_G3H - 16.69v (is it too low? actually my J6900 pin1 (PP18V5_DCIN_FUSE) is the same reading) -- That is perfect.

4. SMC_BC_ACOK - 0v -- U7000 screwed up

when only battery pluged:

1. PP3V42_G3H - 3.49v

2. PPBUS_G3H - 12.23v -- Not good. Should be 12.56. Could be dead U7000, or dead SMC or both, I would lean on dead U7000. Measure R7051 and 52 and replace them. Replace U7000 at the same time. DO NOT power the board on with new resistors with the old u7000, you will blow them again

4. SMC_BC_ACOK - 0v

5. SMC_RESET_L - 3.45v

por

I checked R7051 and its resistance is increasing over time, now is 65.3 ohm. R7052 is 0.7 ohm which should be at 0 ohm. I will replace both in case they are all blown by U7000 already. Thanks for your advice!

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I would suggest trying to replace the mag-safe board.

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Yeah, will do. Need some time to wait for the part coming :)

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No. PPDCIN is present. That will do nothing.

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@j0vian - The MagSafe (MacBook Pro Unibody 13" and 15" MagSafe DC-In Board) in this series is passive, it's only the connector block. So unless the connector its self is damaged then it doesn't make sense to replace it. I would have guided the OP to this Apple T/N if I was suspecting it was an issue: Apple Portables: Troubleshooting MagSafe adapters.

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