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MacBook Pro A1278 (820-2327) Powers On For 3 Seconds
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abuholm [ 12 дек 2018, 14:08 ]
Заголовок сообщения:  MacBook Pro A1278 (820-2327) Powers On For 3 Seconds

Hi everyone, this macbook came with a short on u7300 and connected mosfets. After replacing all affected components and resistors, the board powers on and fan spins for 3 seconds and goes off. In that 3 seconds all voltages on the coils rise. I also noticed that SYS_ONEWIRE voltage is 2.88v but the Green light is on and the battery charges. I am at a loss on what to check next and any help will be appreciated.

recordsman [ 12 дек 2018, 16:13 ]
Заголовок сообщения:  Re: MacBook Pro A1278 (820-2327) Powers On For 3 Seconds

hi there! no liquid demage on board?
if TPS51116 U7300 was in short via PP1V5_S3_REG =DDTVTT_EN
L7320 and VOLTAGE=1.5V after
you must check DDRREG_PGOOD
change DDR3 plates
also need to be checking
C7342 C7341 C7308 C7307
i think this board after water demage...

abuholm [ 12 дек 2018, 19:56 ]
Заголовок сообщения:  Re: MacBook Pro A1278 (820-2327) Powers On For 3 Seconds

Thanks for the response, I have checked and there is no short on the capacitors. DDRREG_PGOOD and MEM_VTT_EN rise to 3.4v when I power on and then power goes off..

recordsman [ 13 дек 2018, 10:47 ]
Заголовок сообщения:  Re: MacBook Pro A1278 (820-2327) Powers On For 3 Seconds

so strange//
SMC drop off power i think, try to find damaged in second rails...

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