PU-22 MM3 modchip installation diagram

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.

For more information about MM3 chips click here, for more information about PS1 modchips click here.

PU-22 MM3 modchip installation diagram

MM3 chip pinout

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.

Installation tips

Here are some tips I have for you when you are soldering your chip into the PU-22.

  • You don’t need to connect pin two, or pin four.
  • 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.

Diagram success rate

Here’s a list of people who have successfully modded their console with this diagram. Leave a comment and I’ll add you to the list.

  1. William Quade (me) (I’ve used this diagram many times and haven’t had any problems with it)

Example installations

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 image shows 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.

PU-22 MM3 install

Below is a messier installation using the diagram at the top of the page.

PU-22 MM3 install

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Nathan Face
Nathan Face

I’m guessing I don’t need to put the metal shield back?


Today i modded my new ps1 fat from eBay with this Diagram!
However It seems like The Chip Doesnt Work properly
I Can Start a Backup of ntsc dino Crisis only – Original Games dont load and a pal Backup of resi derectors cut doesnt start also
My questions:
The chipped ps does not Play Original pal Games anymore? Why? It should do so, Right?
Why does The ps Play a ntsc Backup But no pal Backup? The Chip should Play both types!
Where does This cracking stucking sound playback come from within of an Intro of a game? Too Long wires?