I am probably not the first person to come across this problem, but in case it has not been posted yet, I will post one of my own. Sorry for no pics, I have to be at work in a few minutes.
When I plug in my PSPs wall charger to my stock plug on the PSP, it activates USB mode. Thats because there is power going through the wire used for the USB charge mod, and into the USB port, causing it to become acitve. Place a zener diode in the middle of that wire, so the power is directed from the USB port pin TOWARD the power plug. This way, you can still charge via USB, but plugging in the wall charger will NOT power up the USB port. Also, this is a good way to be able to use your wall charger and your USB cable at the same time, if you happen to have both still installed.
