This is my favorite version of the PlayStation 1. It's in newer systems, so the lasers are more likely to still be in good condition, but the system still has both the serial and parallel ports on the back. This board was used primarily with the SCPH-7500 series of systems.
I sell MM3 modchips in my store.
PU-22 MM3 modchip installation diagram
Above is the diagram for the PU-22. Pin four is located towards the top left side of the board.
This diagram is fairly straightforward. There aren't really any tricky points, or surface mount components you need to solder to.
Here are some tips I have for you when you are soldering your chip into the PU-22.
- Cut your wires to be as short and direct as possible.
- Don't connect pin two of the chip to anything.
- Pin 4 can either be connected to the pin 4 location in the diagram, or pulled high by connecting it to pin 1 on the chip.
- Watch out for solder splatter when you are desoldering the metal shield on top of the board.
- Placing the chip where the pin seven circle is seems to be the ideal location.
This section has photos of some successful installations which you can use to get a better understanding of how everything is wired and positioned.
Here are some sample installations I have done in SCPH-7501's:
This first images show a cleaner way to install the chip with six wires. I probed the board with a multimeter to find alternate points to solder the wires to that are much closer together. I use the capacitor to the right to get the VCC and GND (pins 1 and 8) connected to the chip with really short wires.
Below is a messier installation using the diagram at the top of the page.