MacBook is not booting, no chime, just the fan spins on full speed

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2010年中 MacBook Pro 13" 一体化机

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Niklas Jakob @niklasjakob

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发帖于: 2018年11月7日

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MacBook is not booting, no chime, just the fan spins on full speed

Hey there i have a wierd Macbook.

The Macbook starts, fan starts to spins then shuts down and automaticly starts again it takes a few seconds and than goes full speed on the fan. No image no Backlight.

I checked all Power Rails =

Macbook is in S0 state - all power rails are good except PPVCORE_S0_CPU is only 0.15V

I reflowed U7400 and after the reflow WOW it worked. Ran the ASD all fine passed every test.

BUT next boot, back to the start same thing again .

Then I replaced U7400. WOW it worked. Ran the ASD all fine passed every test.

BUT next boot, back to the start same thing again .

So i guess there is a bad capacitor or something i heated up and made it get better temporary.

Or did i miss something? How do i find the bad cap the easiest way?

thank you for your help

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arbaman @arbaman

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There are not tricky poly-tantalum capacitors on PPV core. It might be a bad U7600, I’d try replacing that IC and the four mosfets too.

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i did change the u7600 and the mosfets but still the same result. Little bit confusing is that the voltage increased sligthly to 0.18v on PPVCORE. do you have another idea?

由 Niklas Jakob 完成的 2018年11月7日

Do you know how u7400 works? I just got 0.2V on the Gates of the Mosfets on the two ugate from the u7400. Seems pretty low.

VRON is 3.38V i think this is to enable the chip.

由 Niklas Jakob 完成的 2018年11月7日

You can look for ISL9504 online, but it's an old IC, not sure you can find any details about it. Here you can find some basic info: https://www.intel.com/content/dam/www/pu...

由 arbaman 完成的 2018年11月7日

its running now will need to test it if it will last. i just rework the hole area around the u7400. and it seem that it was a bad soldering connection i guess... i will see. thank you for your help

由 Niklas Jakob 完成的 2018年11月8日

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i did change the u7600 and the mosfets but still the same result. Little bit confusing is that the voltage increased sligthly to 0.18v on PPVCORE. do you have another idea? — Niklas Jakob
Do you know how u7400 works? I just got 0.2V on the Gates of the Mosfets on the two ugate from the u7400. Seems pretty low.

VRON is 3.38V i think this is to enable the chip. — Niklas Jakob
You can look for ISL9504 online, but it's an old IC, not sure you can find any details about it. Here you can find some basic info: https://www.intel.com/content/dam/www/pu... — arbaman
its running now will need to test it if it will last. i just rework the hole area around the u7400. and it seem that it was a bad soldering connection i guess... i will see. thank you for your help — Niklas Jakob

2010年中 MacBook Pro 13" 一体化机

MacBook is not booting, no chime, just the fan spins on full speed

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