PU-8 MM3 modchip installation diagram

This was one of the earlier PlayStation 1 board designs that included RCA composite video output ports on the back. Most SCPH-1001’s here in the United States had this board inside.

Additionally many Japanese systems had this board including many SCPH-3000, SCPH-3500, and SCPH-5000’s.

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

PU-8 MM3 modchip installation diagram

MM3 chip pinout

PU-8 MM3 modchip installation diagram

Above is the diagram for the newer version of the PU-8 board. It has the smaller CD mechanics controller chip right next to pin 3.

All of the points being soldered to are pretty straightforward pads. They are all located on the bottom side of the board. You can ignore the other chip on the board. Some early PS1’s had a chip soldered like that onto the board from the factory.

Below is the diagram for the older version of the PU-8 board. It has the larger CD mechanics controller chip right next to pin 4.

MM3 PU-8 alternate diagram

Installation tips

Here are some tips I have for you when you are soldering your chip into the PU-8.

  • 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.
  • Placing the chip towards the middle of all of the pads you need to solder to is ideal. If you flatten the legs on the chip it will fit underneath the board without any modifications.

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 to mod one SCPH-1001 and didn’t have 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-1001’s:

This 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. The only real tricky point is soldering pin six to the leg of the surface mount chip.



PU-8 MM3 install

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October 17, 2018 8:20 PM

This is a great, definitive guide to console modchipping. Very accurate and detailed info. All I have to say from my experience with xeno GC and a ps1 mod from experience is that you shouldn’t worry too much if your freshly modded console doesn’t function properly after your first batch of tests. I have noticed on both a GameCube and a ps1 that it doesn’t seem to work after testing. However if you just let the console power on and off time to time the modchip should eventually ‘communicate’ to the console board and function as intended. Not sure if… Read more »

Nick stovall
Nick stovall
October 20, 2018 3:16 AM

Thanks for the install guide bought some chips off you a long time ago I was able to install it in the matter of about 10 minutes and it fired my backups right up

March 10, 2019 1:29 AM

This is the best and most detailed guide that can be found in 2019 to hardmod PSX.
I modded my PU-8 PSX using this guide. Here is the result

The CD reader seems a bit picky but nothing that Verbatim CD’s can’t fix.
Thanks for the guide!

February 21, 2020 2:51 PM
Reply to  carbonyle

I love the original 1001 models of the playstation, but the cd laser isn’t the best on these. I was able to swap mine with one from the newer slim psone consoles and it works amazing now. Just wanted to mention that if anyone is interested. Going to try this modchip install today, been wanting to play some imports.

David Doherty
David Doherty
June 3, 2019 4:05 PM

This absolutely works with an SCPH-1002 and an MM3! I didn’t realise that the MM3 was Stealth for the 1000 Series machines! Thanks William!

Leah Rowe
June 25, 2019 9:51 AM

Hey there 🙂 Thank you for these guides. I used your guide and, with a multi-meter, buzzed around on my PU-8 board to get closer soldering points. Most soldering points can be done directly to the drive controller chip. Well, a picture speaks a thousand words 🙂 See here for how I did my install:


Then I improved it in this follow-up:

December 26, 2019 5:38 PM

Hello. Thank you for this great guide. I bought a chip mm3 on eBay to install it on my PU-8 1001 psx. I installed it using the second picture. All solder ok. The thing is that 1 out of 15 times that I boot a game will work. It gets stuck at the playstation logo almost every time. I use verbatim CDs and I also tweaked a lot of times the POT on the laser. Nothing works, it’s frustrating. If you have another tip or if you can let me know what I’m doing wrong I will really appreciate. Thank… Read more »

July 8, 2020 3:23 PM

hey just wanted to say that im glad people found my install diagram useful, i made that image a few years ago and uploaded it to eurasia before they shutdown, i still to this day can’t figure out what that PCB module is that’s installed on the bottom of the board, its not a modchip, the console wouldn’t boot backups until i installed the MM3, so i have no idea what this module is used for, if anyone has any idea please let me know

July 10, 2020 9:02 PM
Reply to  William Quade

Hey I’m back. I’m about to swap out the mm3 for a psnee in my scph-1001 and I took a few more pics of my motherboard with that weird chip, where can I send you these? Should I upload to imgur and share the link?

July 10, 2020 9:12 PM
Reply to  William Quade
July 20, 2020 5:19 PM

I return to thank you for your documentation once more. I used your diagrams to install the SIO-X switch board. I’ve also used an alternate soldering point for the reset. My PU-8 didn’t match either board exactly. There’s a small piece of paper towel that was removed prior to putting it back together.