Motherboard SMDs missing “tinned” side after water damage

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MacBook Pro 13インチ Late 2020 (2つのThunderboltポート)

2020年11月発売。MacBook Pro 13インチモデルは、8コアのCPUと8コアのGPUを搭載したAppleのArmベースのM1 SoC。(モデルA2338 / EMC 3578、Thunderbolt 3ポート2基搭載)

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gatortpk @gatortpk

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投稿日: 2023年3月12日

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Motherboard SMDs missing “tinned” side after water damage

There was minor corrosion on a late 2020 M1 MacBook Pro logic board caused by water.

Here’s the initial wide view of the corrosion:

I was able to get the MacBook the same day and clean up the corrosion that evening. It didn’t look too bad, but after putting the logic board back in and connecting the battery, the fan spun up a few times and now it’s unresponsive.

The owner did do all the wrong things such as trying to turn it back on and charging it after spilling a little water on it. Hopefully that isn’t what killed it for now. Most of the corrosion was around the USB C ports, so I cleaned those as well. (Now I’ll be replacing them to rule them out.)

Below are an couple pictures after cleaning with distilled water and alcohol and a horse hair brush. I didn’t try any ultrasonic cleaning yet. My main concern are two SMDs that appear to be missing their “tinned” contact on one side (left toward the large chip). Is that what it looks like from the picture and could that likely be the culprit or at least one of the issues? Would those SMDs have lost continuity with the logic board trace below? Here’s a couple pictures at 10x and 20x magnification:

(I haven’t tried the logic board in a different upper case to rule out the keyboard, etc causing start up issues because I don’t have one.)

Thanks for any suggestions!

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Alisha C @flannelist 評価: 33.4千 26 37 33 · Answer 1 · 2023-03-12T14:50:51-07:00

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Alisha C @flannelist

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They could be an issue. That’s part of the power rails for the WiFi chip. Which is the big grey one that’s right there. But even if they’re oxidized on the surface of the soldered ends, they may still work perfectly fine.

If you have a multimeter you can check to see if they are short to ground. (You can use diode mode, or resistance mode for this).

I would actually be more concerned about this area.

It’s possible it cleaned up totally okay. But the two Texas Instruments chips (CD3217…….) cause a lot of hassles with regards to power issues in MacBooks. They are the controllers for the USB C ports and are part of the process involved in negotiating charge voltage (USB C is capable of outputting in several voltages).

In most models, they are encased in an epoxy sort of resin (underfill), like the WiFi chip. You can tell it’s got a border of resin around it and over some of the surrounding components. But these don’t look like they are. Liquid damage under there could cause some weird issues depending on how far it made it under the chip. That area of the chip carries signals for a few power rails. And if there’s no underfill, there could still be corrosion under the chip that you can’t get with isopropyl alcohol and a brush.

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Thank you very much for that info! That makes a lot of sense.

Would you suggest an ultrasonic cleaning, that could get any hidden corrosion under the Texas Instruments chips? I suppose I don’t have anything to lose. First I’ll check the SMDs next to the WiFi chip and see if they’re short to ground.

That does concern me that those Texas Instruments chips are responsible for the higher voltages to the USB C ports and that other damage besides corrosion could have happened when the owner tried charging and turning the MacBook on.

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MacBook Pro 13インチ Late 2020 (2つのThunderboltポート)

Motherboard SMDs missing “tinned” side after water damage

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