Delete comment from: Ken Shirriff's blog
Thanks for the write up, this was super interesting. And you actually saved me - for 2 years now I thought that my Macbook did have some kind of defect DC in board, but I always shied away from the complicated repair, since I was still able to charge it via a USB-C to Magsafe 2 adapter.
Now I took the time to test my 2 original Apple chargers and turns out - 1 of them is dead completely (0V at the Magsafe adapter) and on the other one I replaced the cable, but the replacement cable is apparently a cheap one and doesn't have the chip or something else is dodgey. I didn't get the ~3V, but only 1.9V.
So I now moved the original Apple cable of the 1 charger over to the working other one. And there we go - 1 fully working adapter.
One thing I am wondering about though: reading out the chip with the Arduino only works for me with the 2 original Apple Magsafe 2 plugs. All replacement ones I have, including the working USB-C / Magsafe 2 adapters, do not provide any data. However - once I plug them in (adapters via USB-C charger, the fake cables via lab power supply), they actually charge, the LEDs work correctly and in System Profiler I can even see (different) serial numbers for them. How does that work?
Do you think they have a custom logic implemented to provide correct data if it is requested? And if yes, why can't I read it via the Arduino?
So thanks again. I have back now 1 working proper 100% Apple charger. And I know that I can use the cheap components to build a 3rd party charger, if I ever have a constant 20V power supply available. :-)
Jul 1, 2022, 4:09:48 PM
Posted to Teardown and exploration of Apple's Magsafe connector