MacBook Pro chime + no Video + Board is getting very hot

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2011年初 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18日

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MacBook Pro chime + no Video + Board is getting very hot

Hello Again,

i was wondering if any of you guys have encountered this problem before.

Ive got a Macbook Pro 2011 13” which has been water damaged. There were no obvious signs of corrosion. I had a green light but it was not turning on.

1. I found out i had a short on PPBUS. More prezise PPBUS_S5_HS. Found the short on Q7550 and replaced it.

That kind of fixed it. Now i have fan spin. Looks like it is working.

2. But when i tried it the first time i had no chime and artifacts on the screen.

I reset the SMC and rebooted. Now I have fan spin and a chime. BUT no backlight + no video at all.

I tried to reset the PRAM/NVRAM but that is not working at all?!

The board is getting very very hot.

I think there might be another short on the CPU that caused the Q7550 to fail in the first place.

But I would like to be wrong and some one has another explanation.

Do i miss something? How should i proceed?

Battery is new.

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All the Power rails seem to be good. the only one that looks odd is the firewire PPCP_FW line it is 13.6V instead of 12.8V.

由 Niklas Jakob 完成的 2018年11月26日

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All the Power rails seem to be good. the only one that looks odd is the firewire PPCP_FW line it is 13.6V instead of 12.8V. — Niklas Jakob

Jinajon @jinajon 声誉积分: 321 iMacGyver 5 1 · Answer 1 · 2018-11-20T03:03:14-07:00

I don’t have a hard-and-fast answer to your question, but I may be able to help you.

I use a product called “Freeze Spray” which is FANTASTIC stuff, and saves me endless hours fault-finding.

Basically you remove power from the board you are diagnosing, and spray a suspect area with the freeze spray. Give it a bit to cool down and frost over, and then apply power to the board. As soon as you apply power, any shorted components will heat up very quickly, and will cause the area to ‘defrost’ from an obviously identifiable location, allowing you to very quickly identify shorted components. (It is ‘nice’ if you can use a current limited power supply, but this isn’t always possible.)

There are plenty of how-to type videos on YouTube if you want to see what this process should look like.

Also, if you are doing water damage repairs and you do not have an ultrasonic cleaner, get one. They are a necessity for any water damage repairs. You can get cheap ones to get you started, but if you can, move up to a Crest CP500HT. What an ultrasonic cleaner does is clean your circuit board, but it gets underneath chips, BGAs, and other places you otherwise couldn’t. Many of the water damage repairs I have done went from a brick to booting up simply after a couple of minutes in the ultrasonic cleaner.

I hope this isn’t “preaching to the choir”! And I wish you good luck with the repair.