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Comment by luma | Hacker News Reader

It's still very useful for repair techs (and I don't mean parts-swappers, I mean actual techs). This data is pretty quickly reverse engineered and shared in China, and then made available to shops through services like ZXW, WuXinJi, JCID, etc. There's an entire shadow industry around creating and then sharing schematics and PCBs for common products which might need repair.

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It's not really useful for most repairs. These PCBs are very dense. The traces and even vias are buried below the surface. At best it might give them some hints about where to probe if they've never worked on that phone model before, but in a practical sense they're not going to be doing many repairs based on the schematics.

The repair process for a modern phone involves swapping salvaged parts on to salvaged PCBs.

Most of the parts on the PCB are custom and not available for purchase separately. The passives aren't likely to be points of failure, but even when they are they're usually swapped from some other donor board rather than purchased new.

> The repair process for a modern phone involves swapping salvaged parts on to salvaged PCBs.

Right, but, knowing what the nominal in-line resistance is between any two pins on the board, will let you do some empirical tests to determine whether a given black-screen fault lies in the board itself, vs in one or more of the SMT components, no? (And so whether you should bother attempting to salvage the board, vs just scraping off the high-value parts and chucking it in the bin.)

This reminds me of https://www.youtube.com/watch?v=reQq8fx4D0Q

>These PCBs are very dense. The traces and even vias are buried below the surface

You are so out of touch, PCB repair is very common.

This is just one example of via/pad repair: https://rewa.tech/iphone-12-pro-max-not-booting/

The whole repair industry in China is really insane.

>The repair process for a modern phone involves swapping salvaged parts on to salvaged PCBs.

This is always the case, but there is difference between swapping the whole camera module and just swapping the camera lens.

Hell they even use fiber laser to fix stripe line screen.

That's assuming they can get their hands on the "black box" ASICs

I suppose you could transplant the chips from a damaged board.

Yes, that's what people like Louis Rossmann famously do. Apple, in turn, tries to serialise each chip and make it only boot if all the serial numbers match.

You don't need a schematic to do that.

Aftermarket board and passive components; transplant the Apple chips from a damaged board. Then you don't need to cannibalise the board, you use a new one.

I assume most physical damage and corrosion etc affects the board and passive components.

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