In April I wrote a post about installing an MM3 modchip into my PSone with the original PM-41 board. I have also written a post about installing an MM3 modchip into my SCPH-7501 with the PU-22 board. This is a similar post, but covering the final revision of the PS1, the PM-41 (2) board.
Before I begin I'll give you a little bit of background information. I purchased eleven PSone consoles on eBay with the goal of installing MM3 modchips, and reselling them for a decent profit. Out of the eleven consoles eight were the older PM-41 board design, and three were the newer PM-41 (2) board.