Macbook Pro M1 A2338 - how to test for 20V?

[jkruns]

I have a stack of liquid damaged A2338's, most of which don't draw more than 5v and thus won't turn on.
So far I've put back the main boards back after cleaning and repair attempts and connected every single component before testing. This obviously take a huge amount of time.

My question is (maybe not limited to A2338 boards): what's the bare minimum that needs to be connected in order to test if it will draw 20V? Should it draw 20V without the battery connected?

[tomtom67]

I always test for 20V with the bare board, so nothing needs to be connected but the USB adapter. Some models need battery and/or trackpad connected to fully boot though.

In FlexBV / OpenBoardData there is one solution/checklist available to ease in 20V startup debugging.

Just had a Coke bathed A2337 here that put up a fight; turned out there were two tracks disconnected and a bad resistor in the ISL area, plus both double-mosfets (Q5230, Q5240) were blown.

[jkruns]

Thank you for that!
With regards to FlexBV, would you say it's worth the investment just for the solution/checklist?

[tomtom67]

As gar as i know even the free version has openboarddata integrated, so you may be fine with it. But as sattes on his web site, the first two jobs will pay the license fee, plus i wanted to support PLDs work. I mean it’s not much money compare to other tools, and well worth it.

[reformatt]

The butterfly mode (where it shows both sides of the board simultaneously and the connection lines between nets between the two) is a real time saver. The integration between selecting a component on the boardview and auto selecting it (or at least searching each instance) in the schematic is huge.

If you are doing frequent board repairs, it pays for itself just in the time you save. The Openboard data is a bonus. Paul has done amazing work on this and should be rewarded for it.