Strange AGS-101 Game Boy Advance SP problem

[Tokimemofan]

I have seen a lot of units with charge problems that seem to defy explanation. They seem to start by being picky with which charger they work with and eventually won’t charge the battery at all unless the charger is reinserted 3-4 times rapidly
I have seen this on many broken systems.
It is not a battery problem.
It is not a charger problem.
If a working already charged battery is inserted it will power on normally but the charge issue persists.
It does not seem to happen to AGS-001 as far as I have seen.
Things I have checked:
F1/F2 work
EM8 is good with no solder joint problems.
Charge port is clean, replacing does not fix this.

I suspect the problem is with the Mitsumi PM B3 but have no way to test this and there is no pinout for this chip.

 

[la-li-lu-le-lo]

I’ve encountered this problem with an AGS-101. Like you said, it’s not the battery or the charger, so it must be some part of the system. I ended up returning the problematic system and getting another one, and that one still works just fine. I don’t know what causes the issue, but it seems like some systems have the issue and some systems never develop the issue. It could be due to a manufacturing defect or a part that was only used in some units, although I thought all the AGS-101 systems were identical.

 

[Tokimemofan]

I’m going to be checking the Mitsumi PM B3, it is very similar to the Mitsumi PM C in the gameboy micro and I have seen those fail. These chips are labeled PMIC, but I suspect that they aren’t just for power management. It would be interesting to see if AGS CPU 30 boards can fail like this too. Japan never got the 101 but the last board used in Japanese units has the same layout as the 101.

 

[Tokimemofan]

Finally tested it, the PM B3 is not the cause of failure, will continue investigating.