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.

  • 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.

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 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.

PU-22 MM3 example installation

PU-22 MM3 example installation

PU-22 MM3 install

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

PU-22 MM3 install

Subscribe
Notify of
guest
59 Comments
Most Voted
Newest Oldest
Inline Feedbacks
View all comments
Nathan Face
Nathan Face
April 6, 2018 4:24 PM

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

Volker
Volker
May 31, 2018 10:10 AM

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… Read more »

Mario
July 17, 2020 5:32 AM
Reply to  Volker

I think your laser assembly May be a little bit tired.Try another laser assembly, or cheap chinesse replacement. Túry read fine byť ste a little bit nikdy.

gregor
gregor
June 27, 2018 6:50 AM

what is my problem if i can play originals and pal copies but no ntsc games with my chipped ps?

gregor
gregor
June 27, 2018 5:36 PM
Reply to  William Quade

Hm the board is pu-22 1-671-858-21 wired like the the diagram shows
Is probably number 1 in the diagram for the ntsc region?
I guess that one soldering contact isnt right then…with a ntsc backup the cd player menu pops up, tv works fine.
I also have a boot cd and i can run ntsc games with it but i dont want to use it because its obviously chipped :/

gregor
gregor
June 27, 2018 6:51 AM

its an mm3 chip inside

Conner Allred
Conner Allred
July 13, 2018 2:54 AM

Worked for me on my 22!

Richard Bettridge
Richard Bettridge
September 6, 2018 2:32 PM

Why isn’t pin 4 required? I think pin 2 is for non-stealth firmware (rough google) but why not 4.

Daniel
Daniel
October 27, 2018 8:16 AM

Followed the instructions and installed MM3 to my original PlayStation from my childhood. Thanks very much.

Wrameses
Wrameses
November 16, 2018 10:14 AM

Is it ok to clean the motherboard with rubbing alcohol? I just want to clean a little residue

Globby23
Globby23
November 25, 2018 9:20 AM

Hello I need help. When I turn on my playstation there’s no display. The spinner isnt running but the laser on the cd spinner is on.

Naeem Ali
Naeem Ali
January 30, 2019 2:12 PM

Hi there, thanks so much for posting up this guide I’m looking to try installing the modchip using a tidier method. I’m thinking, could I solder directly to the motherboard’s respective chip legs instead of their pads? Say for pads 7, 3, 6, and 5. I’m thinking if I simply follow the traces back to their corresponding motherboard chip leg, could the modchip still work (provided I use good technique and a fine solder tip). I’ll basically follow the pad back to the leg by eyeballing the trace in between them first, then confirming with a multimeter. To this end,… Read more »

Terry
Terry
February 6, 2019 11:08 PM

Hey, so i installed the prewired chip i purchased on ebay. Now my ps1 boots fine to the no disc menu, but the drive never stops spinning, like it cant focus. Left the top off and it seems like the drive sends the laser out as far as it can but never finds anything, physically moving the laser just sends it back out. I swapped it out with another drive from another 7501 that was verified working and it does the same. Both of these drives worked before hand so im not sure whats going on. I double checked my… Read more »

Tracy
Tracy
March 20, 2019 1:51 AM

Hey there, just recently installed the modchip, thanks very much for the guide! It’s been working with nearly everything so far but it doesn’t want to load Pop’n Music 2 (NTSC-J), any time I try to play it I get the anti-modchip “software terminated” screen. Everything else works perfectly including other NTSC-J games and Spyro 3 (PAL version) which I had heard had anit-modchip protection programmed in. Is this a compatibility issue with the MM3 itself or should this game work fine and this suggests that there’s something not wired up correctly inside? Thanks for your time.

Tracy
Tracy
March 20, 2019 3:37 AM
Reply to  Tracy

Some extra information: I’m using a PAL SCPH-7502 model PS1. I’ve done a few more tests with other games, NTSC-U Crash Bash also works fine but Dokodemo Issho does not. It seems like Japanese games with anti-modchip screens are the problem, although I have managed to run NTSC-J Crash Bandicoot 3 without any issues.

e5frog
e5frog
October 15, 2019 10:33 PM

Nice!
The install images showing the numbers are quite small and grainy but the clean PU-22 installation with short wires using alternative solder points is nice and HUGE even if it’s not that easy to see the hook up.
Would be really nice to get an image where an old man can clearly see where to solder wires…

Chavez Garza
Chavez Garza
October 25, 2019 10:34 AM

Used the standard long wire diagram for a 1998 7501 console pu 22 board and got it working first try thankfully. Diagrams were great and your pre-programmed mm3 chip worked perfectly. Tip to others: pre tin wires and your board contact points so all you have to do is fuse them with a quick but deliberate touch, and don’t be afraid to use 30 watts to avoid cold bonds. My board was also lacquered, so be sure to clean the sites you need to solder thoroughly with alcohol and Q-tips until they shine.

David Martins
David Martins
November 8, 2019 2:11 PM

Hi there I have a couple questions. I’ve got the pu22 with a modcip installed. However there’s a couple of broken/ripped contact points. So if we look at the pic with the Sony cxd2938q just under it there’s a solder point where you have wired part of the chip (just above number c637 has a little trace to the CPU (think it’s the CPU) leg that one is broken off with the copper so all I have left is the trace….. The other point broken is the one just just below number 53. My question is can I straight solder… Read more »

Andrew Scott
January 24, 2020 9:48 AM

Hello William! This was my first time soldering anything ever! and i feel it went well. with pre-practice and your instructions. So at this point when i try to play a burned game, sometimes it goes to the default ps1 menu, other times itll make it to the black ps1 screen, a few times its gone to the default ps1 menu then after about 10secs it goes to the black ps logo screen then does nothing else, and once it even ALMOST loaded the game up. made it to the first screen past the black ps1 one, and then froze.… Read more »

Andrew Scott
January 24, 2020 5:09 PM
Reply to  William Quade

So I swapped out a laser from my other ps1 and now it works perfect! You’re a legend man. I really appreciate everything you do!

sam Riscile
sam Riscile
February 22, 2020 4:33 PM

Unfortunately i overheated contact point 6 but was able to solder directly to the board mounted capacitor, watch for splash & shorts, reinstall the heat shield, All good playing my most of my backup CDs I think I need a new laser

Leah Rowe
March 13, 2020 2:26 PM

hey will, i’m making a website covering PS1 modchip installs, among other things. I do them voultar-style though, so the guides are a bit harder to follow but the resulting mod is much cleaner. I have this guide:
https://retrofreedom.com/ps1pu22.html

What do you think?

Jeppe Krogh
Jeppe Krogh
March 20, 2020 4:45 PM

Hello William, nice of you to put a well documented guide here, i appreciate that 🙂 However, i seem to have run into a problem. I bought a MM3 chip from ebay for my SCPH7502, and followed your guide, up until i got to the solder-point number 6 on the board. There doesn’t seem to be any metal in this spot that i could solder the wire to. (sorry for my weak terminology lol). I don’t know if this PSX has been chipped before, but all of the other solder-points were untouched. My question is: Is there an alternative solder-point… Read more »

Luis Brenes
Luis Brenes
March 27, 2020 10:21 PM

Worked perfectly for me, I placed the chip over the “A” on the motherboard with double sided tape. Thank you!

John
John
May 5, 2020 7:33 PM

Wth I was trying to be super delicate and I’ve done tons of 9001s and 101s, but on this 7501 I got all the traces just disintegrated

Zeph
Zeph
May 8, 2020 3:44 AM

Yay I finally got a chip installed with the long wire points. I had killed 3 PSOnes before this so I decided to try an older model and it worked! The first time I had taped up the wires a bit and put the metal cage back but it didn’t even turn the disc spinner on. So I took it back apart and shortened a couple cords and redid the couple of points I wasn’t sure about and then left the tape and the cage off the 2nd try and it loaded the games up flawlessly! I do get a… Read more »

Greg L
Greg L
May 15, 2020 4:30 PM

Hi William, Thank you so much for all your work. You make things so much easier for us green hobbyists. I really appreciate all the work you’ve done. Im getting ready to mod my ps1 with your information, here, and I have a question about the process. I’ve discovered that my PS1 is a PU-22 SCPH-7501. In this diagram, you’ve listed two different PIC’s but did not mention the ones I have on hand. I do see that you listed them (PIC 12F629) in the very beginning of the installation guide, but its not mentioned on this page, so I’m… Read more »

Ilya Dyadkov
Ilya Dyadkov
May 26, 2020 12:21 PM

Working well on 7502 (PAL), chip 12C508A programmed with K150. William, thanks a lot !!!

Fez64
Fez64
June 18, 2020 7:28 PM

Having trouble with a PU-22 MM3 mod, It only seems to read whatever disc I put in as an audio CD, official or backup.

Marc
Marc
June 26, 2020 9:38 AM

Hi there,

I have managed to destroy the trace on the board that point 5 goes to. It’s a really short trace to a solder pad. I’m preparing to lift the pin on the chip and repair it with wire, but I’m really struggling to see where that solder pad went to, it looks like it just disappears? Can you help?

Marc
Marc
June 26, 2020 9:42 AM
Reply to  William Quade

Thanks so much for replying. I know I can solder the mod chip directly to that leg, but I’m worried about the existing trace being broken. I’ve destroyed the trace and that solder point. Are you saying if I solder the mod chip directly to the leg of the chip I don’t need to worry about that original trace?

Marc
Marc
June 26, 2020 10:23 AM
Reply to  William Quade

Thanks for the reassurance, I connected pin 5 by lifting the corresponding leg on the CD-ROM (I guess?) chip and it works fine 🙂 I really am curious as to what that small trace and solder point is for though. Do you think its more or less unused?

Mike
Mike
July 5, 2020 5:50 AM

I bought from aliexpress a modchip 12c508 12c509
here is the link
https://www.aliexpress.com/item/32862535900.html?spm=a2g0s.9042311.0.0.bdff4c4dqH9gGK
I want to ask is the modchip I buy is the mm3 modchip?
Thanks

Mike
Mike
July 5, 2020 9:34 AM
Reply to  William Quade

Do you have a link on where to buy mm3 modchips?
Thanks

Oliver
Oliver
July 20, 2020 11:32 AM

I just installed the chip and put my PlayStation back together, it turns on and outputs video but will the disc drive does not rev up. I’ve tried checking my connections and manually holding down the button which tells the ps1 the drive is closed, but it won’t rev up.

Oliver
Oliver
July 21, 2020 7:32 PM
Reply to  William Quade

I’ll check over the wires and see if I can find any shorts. I’ll also try removing the chip and see if its my ps1 but it was working before.

Retro_Rok89
Retro_Rok89
September 8, 2020 5:38 PM

Thank you very much for this guide!
I used it today to mod my PU-22 SCPH-7502.
It was a bit tricky to solder all the wires to the motheboard, but in the end, I’ve managed to do it.
Now it’s working great!