PU-18 PsNee modchip installation diagram

This board was used with a wide range of consoles from the SCPH-5000’s, and SCPH-5500’s, to even some SCPH-7000’s and SCPH-7500’s.

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

PU-18 PsNee modchip installation diagram

PsNee ATtiny45 pinout

Arduino pinout:

  • Pin VCC – VCC
  • Pin GND – GND
  • Pin 3 – Debug TX
  • Pin 4 – BIOS A18
  • Pin 5 – BIOS D2
  • Pin 6 – SQCK
  • Pin 7 – SUBQ
  • Pin 8 – DATA
  • Pin 9 – GATE_WFCK

PU-18 PsNee installation diagram

Above is the diagram for the PU-18.

All of the points are fairly easy to solder to.

Installation tips

Here are some tips I have for you when you are soldering your chip into the PU-18.

  • Cut your wires to be as short and direct as possible.
  • You don’t need to connect pins one and two of the ATtinyX5 chip. Just desolder the wire.
  • A good place to put the chip is underneath where the legend is, towards the middle of everything.
  • Use a multimeter to probe around for alternative VCC and GND points closer to where you position your chip for a cleaner installation.

Example installations

This section displays example installations to help you get a better understanding what a successful installation looks like.

  • William Quade (me)

PU-18 PsNee example installation

  • Nall Wolf

PU-18 PsNee example installation

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Jon Stoll
Jon Stoll
November 23, 2018 11:04 PM

This diagram worked perfectly. Only took about a half hour maybe 45 minutes and I was playing some Pepsi Man and all my 100% legal backups. Thank you.

December 14, 2018 4:57 AM

Alright, so this tutorial is great, i finally got it working with an Arduino Nano. I’m going to leave this information here if anyone rips up the pad for DATA and SUBQ. Both of these lead to the CD-ROM SUB CPU BIOS (The chip is above the DATA connection). For DATA, wire one end to the 4th pin from the left (Bottom side of CD-ROM SUB CPU BIOS) and the other to hole right of the pad. Or you can wire the other end to the 1st pin on the left side of the (4 CHL ANLG DEV) – (The… Read more »

Nall Wolf
Nall Wolf
January 2, 2019 2:44 PM

Used the guide to install a PsNee in my 5501, works great (as long as you don’t accidentally swap VCC and GND the first time… Oops!). Here’s a pic of my finished, working install. Don’t mind the grossness on the chip, that’s melted Scotch tape residue caused by my mistake I mentioned earlier.


February 9, 2020 8:28 PM

Found your site quote helpful while researching PS1 modchips so I thought I’d give back and share my Arduino install, used a pro mini clone for mine. My wire routing isn’t the best but I stand by ‘fugly but functional’, and it works fine. I’d tried the pic mod chips previous but I think I have a bad programmer as they never worked.


Andy Sew
Andy Sew
March 18, 2020 3:05 PM

Worked for me!

June 2, 2020 11:56 AM

Yet another successfull install thanks to your guide ! Attiny45 on a 5502, install pic here : http://fichiers.arthus.net/psxdev/modchips/psnee/pu-18-psnee-attiny-mod.jpg
Cheers !

Last edited 4 months ago by Arthus
Travis Price
Travis Price
June 10, 2020 6:39 PM

Hello I have issue getting my PsNee Arduino working. I installed it booted a back up no problem the first time. Swapped the game out for another back up and it wont read any back ups or the first that read as a game. I have adjusted laser. It will go to cd menu and play the disc as audio but not boot into game. Any help would be great. My PS1 is 5501 PU18

August 12, 2020 4:31 PM

Diagram is good. Hardest part for me was my insufficient solder/bad iron IDK wth it is. But finally got it after switching to another solder. Used loctite mounting putty to stick down and keep wires in place on PCB.

August 13, 2020 6:11 PM

Hi unfortunately i need some
Help looping for another point on the bd to solder WFCK?

August 15, 2020 9:58 AM
Reply to  Greg

Found my way with mm3 diagrams point 5 for gate WFCK

August 15, 2020 10:03 AM
Reply to  Greg

Here my bd with the psnee, works fine!

August 15, 2020 10:18 AM
Reply to  Greg

Here the picture!