Dead Raspberry Pi Boards, PMICs, And New Hope

Since the Raspberry Pi 3B+ release, the Pi boards we all know and love gained one more weakpoint – the PMIC chip, responsible for generating all the power rails a Pi needs. Specifically, the new PMIC was way more vulnerable to shorting 5V and 3.3V power rails together – something that’s trivial to do on a Raspberry Pi, and would leave you with a bricked board. Just replacing the PMIC chip, the MxL7704, wouldn’t help since the Raspberry Pi version of this chip is customized – but now, on Raspberry Pi forums, [Nefarious19] has reportedly managed to replace it and revive their Pi.


First off, you get a replacement PMIC and reflow it – and that’s where, to our knowledge, people have stopped so far. The next step proposed by [Nefarious19] is writing proper values into the I2C registers of the PMIC. For that, you’d want a currently-alive Pi – useful as both I2C controller for writing the values in, and as a source of known-good values. That said, if you go with the values that have been posted online, just having something like a Pi Pico for the I2C part ought to be enough.


[Nefarious19] reports a revived Pi, and this is way more hopeful than the “PMIC failures are unfixable” conclusion we’ve reached before. The instructions are not quite clear – someone else in the thread reports an unsuccessful attempt doing the same, and it might be that there’s a crucial step missing in making the values persist. However, such an advancement is notable, and we trust our readers to take th ..

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