PU-22 PsNee 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 PsNee chips click here, for more information about PS1 modchips click here.

PU-22 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-22 PsNee installation diagram

Above is the diagram for the PU-22.

This diagram is fairly straightforward. Be careful when soldering to the capacitor that connects to VCC and GND. In particular, the GND point can easily be bridged to nearby pins/pads.

Installation tips

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.
  • You don’t need to connect pins one and two of the ATtinyX5 chip. Just desolder the wire.
  • Use a multimeter to probe around for alternative VCC and GND points closer to where you position your chip for a cleaner installation.
  • Placing the chip on top of the chip in between SUBQ, SQCK, GND, and VCC is a good spot.
  • Watch out for solder splatter when you are desoldering the metal shield on top of the board. It isn’t necessary to put it back on, but I always do.

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)

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.

  • Jon Co

PU-22 PsNee example installation

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Preto Fonseca
Preto Fonseca
March 16, 2019 7:38 PM

Here’s my contribution, using a Attiny85. The only difference being that i took ground from other pad.
https://imgur.com/a/cZyAMPS

Tom
Tom
November 9, 2019 9:45 AM

Success! I messed up my first attempt by not keeping the leads extremely short. I’m sure it bridged a few traces. It wouldn’t boot backups without glitches. I went back and took my time making sure each connection was right and now it works flawlessly. comment image

John L
John L
November 14, 2019 10:53 PM

Any better locations to pull power from besides the SMD capacitor? My soldering iron has no temperature control and I keep making it come off

Lenny
Lenny
December 11, 2018 9:42 AM

I don’t have a vcc called pin on my Arduino nano is there a different name for it?

Jon Co
Jon Co
December 30, 2018 9:01 PM

I just installed this based on the instructions. Looks like the Vcc/Gnd has the polarities reversed in your diagram.

Mr. Metric
Mr. Metric
January 4, 2019 5:02 PM

I tore off the GATE_WFCK pad. Is there anywhere else I can connect the wire?

Mr. Metric
Mr. Metric
January 4, 2019 5:43 PM
Reply to  William Quade

I know the trace connects to a nearby pin, but I didn’t attempt soldering a wire to it because the pitch is so fine I’d probably ruin it with bridging

EJack
EJack
January 5, 2019 4:15 PM
Reply to  Mr. Metric

This happened to me as well, so I soldered directly to the pin with flux by having as few solder as possible on the tip and soldering a single strand from a multistrand copper wire
Tricky, but that worked

fullmontis
May 17, 2020 6:14 PM
Reply to  Mr. Metric

That happened to me too. For info in case anyone is in the same situation, instead of soldering directly onto the chip pin (which is rather tricky) I ended up scratching away the protective material from the thin track leading to the pad, raising it from the board and soldering the wire to it (and taping it down just to avoid further damage). It is tricky but still a lot easier than soldering directly onto the leg and helps avoid any bridges.

FoD
FoD
March 29, 2019 12:45 PM

Okay, I just did some testing with the Attiny85 and it does not play nicely with something like Tony Hawk Pro Skater 2, and it did not boot the backup. I will have to order some 45s or use the Mayumis I ordered from you.

FoD
FoD
March 29, 2019 1:18 PM
Reply to  William Quade

It works with Konami games, legit SRWF, Fatal Fury, but curiously NOT Tony Hawk Pro Skater 2 on like the second boot or something. I have read that the 85 has limitations compared to the 45, and I guess I found one.

Damien
Damien
June 27, 2019 8:13 PM

I accidentally pulled off the DATA pad. Is there an alternative one?

Damien
Damien
June 27, 2019 8:39 PM
Reply to  William Quade

Thanks. I thought there might be one there!

Vinicius Dornelles
Vinicius Dornelles
June 7, 2020 11:15 AM

can i use this diagram for the connections of PsNee on a arduino mini pro?
 

dean simidis
dean simidis
June 20, 2020 2:50 AM

what are the pin outs for an Arduino uno r3

kenny
kenny
September 26, 2020 5:21 PM

I accidentally lifted the capacitor for the VCC and GND wires. Do you know if that capacitor is polarized?