Had a weird short on a 2018 MacBook Pro board today

I was working on a liquid damaged A1990 board in my shop in Denver, and the 5V rail kept dropping to zero under load. After an hour with the thermal camera, I found a tiny speck of corrosion under a 0201 capacitor near the CD3215 chip, something I would have missed without the cam. Has anyone else run into a short that small causing a full rail collapse, or did I just get unlucky?

4 comments

4 Comments

jamie9403mo ago

Nah, that's pretty normal for those boards. A tiny short can definitely take down a whole rail, especially on the 5V line. The thermal cam is a lifesaver for finding those.

jamie9401mo ago

Brutal luck" is right - I felt that one too many times, like finding a needle under a haystack and then realizing the needle is actually smaller than the hay. @angela_harris nailed it with the liquid damage comment, that's usually what starts this whole mess in the first place. My thermal cam has paid for itself ten times over just from hunting down shorts that I'd never spot with my own eyes.

hollyl253mo ago

Jamie940 is right, those tiny shorts are a real headache on that model. It's wild how a speck you can barely see can kill the whole rail. Good call using the thermal cam, I'd have been stuck for hours without one too. Finding it under a 0201 is just brutal luck. Solid work tracking that down.

angela_harris3mo ago

Honestly that's not just bad luck, those tiny shorts are super common on liquid-damaged boards.