MM3 modchip installation guide

MultiMode 3, or MM3 modchips are very popular, and should work with every version of the PlayStation 1. They can be made using PIC12C508A, PIC12F629, and other PIC chips. This guide covers everything you need to know about choosing, programming, and installing an MM3 modchip into your PlayStation.

Guide structure

This guide is structured into several pages. It’s organized like this primarily so that comments can be more organized and useful for readers.

This page covers the MM3 modchip. It includes general information about the chip, and then links off to installation guides for each console model.

If you want more information about PlayStation 1 modchips in general check out this guide.

MM3 modchip installation diagrams

MM3 modchip

Below is a list of all PlayStation 1 motherboard versions, along with the console model numbers associated with them. You can get a good idea of what board you have by looking at the model number underneath your system (something like SCPH-7501).

To actually know what board you have you’ll most likely have to open up your console and look for the board version printed somewhere on the board (something like PU-22 or PM-41).

Once you know what board you have you can click on the board model and you’ll be sent to a page with the installation diagram.

  • PU-7
    • All SCPH-1000’s
    • Some early SCPH-1001, and SCPH-1002’s
    • Some early SCPH-3000’s
    • Some early SCPH 3500’s
  • PU-8
    • Most SCPH-1001, and SCPH-1002’s
    • Most SCPH-3000’s
    • Most SCPH-3500’s
    • All SCPH-5000’s
  • PU-16
    • All SCPH-5903’s
  • PU-18
    • All SCPH-5001’s
    • All SCPH-5500, SCPH-5501, SCPH-5502, and SCPH-5503’s
    • All SCPH-5552’s
    • Some early SCPH-7000, SCPH-7001, SCPH-7002, and SCPH-7003’s
    • Some early SCPH-7501’s
  • PU-20
    • Most SCPH-7000, SCPH-7001, SCPH-7002, and SCPH-7003’s
  • PU-22
    • All SCPH-7500’s
    • Most SCPH-7501’s
    • All SCPH-7502, and SCPH-7503’s
    • Some early SCPH-9000, SCPH-9001, SCPH-9002, and SCPH-9003’s
  • PU-23
    • Most SCPH-9000, SCPH-9001, SCPH-9002, and SCPH-9003’s
  • PM-41
    • Earlier SCPH-100, SCPH-101, SCPH-102, and SCPH-103’s
  • PM-41 (2)
    • Later SCPH-100, SCPH-101, SCPH-102, and SCPH-103’s

 

MM3 modchip drawbacks

The biggest problem with MM3 chips is how they base their timing on the internal oscillator within the PIC chips. Using the internal oscillator can sometimes cause the chip to become out of sync with the console when booting, meaning you’ll have to restart the console to boot.

Certain PIC programmers can also mess up the internal oscillator value when programming, which could be a problem if you are programming your own chips. Additionally it has been reported that certain batches of PIC chips have had problems with the oscillator value in the past.

MM3 modchip advantages

The MM3’s greatest strength is its compatibility and popularity. From my experience it is the single most popular PS1 modchip being used today. Because of this you’re more likely to find people who can help you if you are having problems installing your chip.

Additionally the MM3 is compatible with most PS1 consoles and can play anti modchip games if you install all seven wires. The only system that you definitely shouldn’t install an MM3 in is the SCPH-102 (install a ONEchip instead).

MM3 modchip source code

If you’d like to program your own MM3 modchips you’ll need the source code. Right now I only have the code for the PIC12C508A and the PIC12F629. If you have the code for other PIC chips let me know and I’ll add them to this post.

The MM3 chip has three different versions, one for each region. If you have an American system use the USA version, if you have a European system use the EUR version, and if you have a Japanese system use the JAP version.

  1. PIC12C508A
    1. MM3 PIC12C508A USA
    2. MM3 PIC12C508A EUR
    3. MM3 PIC12C508A JAP
  2.  PIC12F629
    1. MM3 PIC12F629 USA (assembly source)
    2. MM3 PIC12F629 EUR (assembly source)
    3. MM3 PIC12F629 JAP (assembly source)

I’ll have a tutorial on how to program these PIC chips in the future.

85 Comments
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Subsonix
September 14, 2020 9:19 AM

Hello 🙂 I followed your guide and successfully modified my first console (scph9002)
Thank you so much for your advice

Felipe Chierice
Felipe Chierice
May 2, 2018 11:50 AM

Hi Quade, nice guide!

I have a question, can I write the 12C508A program code into a 12C509A microcontroller, and use the same wire diagram? Thanks for your attention.

Felipe Chierice
Felipe Chierice
May 2, 2018 9:12 PM
Reply to  William Quade

Excellent then, thank you very much for the quick reply! I’ll work on it next weekend and give you a feedback.

Jeff
Jeff
March 24, 2020 8:06 AM

What type of solder and flux do you use?

Matt McGuffey
Matt McGuffey
April 23, 2020 1:32 PM
Reply to  William Quade

Hi William!
Can you additionally suggest a good and reliable fine point soldering gun? Just got my MM3 in the mail from you. Excited to install and rebuild my old JP library I had in high school 🙂

J Matson
J Matson
December 17, 2020 1:03 PM
Reply to  Matt McGuffey

I work as an electronics technician at a college and we use the Weller WES51 series soldering irons with TETS tips. They have worked really well for us, and I highly recommend them.

juri
juri
November 17, 2020 12:46 PM

hi william,
I recently got 2 PIC12C508A chips and I installed one on a psx scph-5502 following your pattern on PU-18 motherboards and it works perfectly with all types of both backup and original CDs.
The only thing is (but I think it’s a psx model problem) that both USA and JAP NTSC games make me see them in black and white maybe you know why?
one last question: the scheme you published ie the 7-wire mod by chance is the so-called stealth modification?
Thank you. Juri.

Juri
Juri
November 17, 2020 3:58 PM
Reply to  William Quade

Thank you for the response!
i read somewhere that the 55xx series psx have the oscillator which does not reproduce the 60HZ signal.
i connected the rgb cable and the result is identical. i also tried it on my 2015 lcd tv and same thing.
do you think it is for the oscillator?

Juri
Juri
November 17, 2020 5:06 PM
Reply to  William Quade

Thank you so much William.
Bye Bye…

Mark
Mark
May 2, 2018 2:57 AM

If I’m interested in trying to program my own mm3 mod chip, do you have a recommended PIC programmer? Did you buy one or make one from scratch? What software do you use for the .hex files, etc? How do I verify that it worked correctly, before soldering it to a PS1.

Thanks in advance. Love the site.

Christopher Spies
Christopher Spies
April 5, 2019 7:00 PM

Does the mm3 come pre programmed I am just wanting to be able to play my ntsc PlayStation so I can play Japanese games on ntsc

Christopher Spies
Christopher Spies
April 5, 2019 8:11 PM
Reply to  William Quade

Which one will I need I have a nstc scph-1001 PlayStation so I can go ahead n order the chip

christopher spies
christopher spies
April 5, 2019 8:27 PM
Reply to  William Quade

So I need to order the psnee chip n is there a diagram on ur website for 1001 playstations

FoD
FoD
April 24, 2019 12:04 PM

The Pic12C508A is recognized by my TL866. Any special way to load and write the hex file? Thanks.

FoD
FoD
April 25, 2019 6:02 AM
Reply to  William Quade

Cool, just like my SNES projects! Thanks.

Stanislav
Stanislav
May 17, 2019 5:38 AM

How to program 12С508 with programmer K150? I did not succeed, it just does not work

D244
D244
October 28, 2019 7:07 PM

hello good site a question also serves the 12C508 / P?

Mike
Mike
February 13, 2020 9:51 AM

What does each pin do exactly for this modchip? Interested in technical details. I got it installed first try so loving it!

Chris
Chris
March 5, 2020 9:41 AM

Hello, I installed the MM3 chip in my PU23 board and when I boot up the PS1 it takes me to the audio CD/memory card screen. I didn’t connect pin 2 to anything and connected pin 4 to pin 1. Any ideas what could be wrong?

Mido
Mido
June 25, 2020 11:53 PM

i have PIC 12F675 can i download MM3 PIC12F629 Hix file and work for 12F675
or i must buy PIC 12F629
what a programmer i can use
thanks for your effort

victor
victor
July 1, 2020 5:09 PM

Hello, I want to buy the PIC12C508A chip and program it myself, what should I do with the code file that you published? And what device should I use to connect the chip to my computer?

lilkuz2005
lilkuz2005
July 13, 2020 12:54 AM

has anyone tried to use cheat devices or cheat discs like gameshark with the mm3 chip, i have tested my 3 cheat carts and like 4 cheat discs with all my modded ps1 consoles running mm3 chips, schp-1001, scph-5501, scph-7501, scph-101, all of them will not work with cheat carts or discs, i think it has to do with the way the mm3 chip uses stealth, on power on the chip will send the wobble code for a few seconds and then stop, well when loading up a gameshark and taking time to pick your cheats the time runs out,… Read more »

Darkbit
Darkbit
August 2, 2020 5:12 PM

This chip will allow a japanese ps1 to boot/play american games normally?

Darkbit
Darkbit
August 2, 2020 5:19 PM
Reply to  William Quade

ohhhh nice thanks, so basically this chip works with any japanese model before model version SCPH-3000 right?

Darkbit
Darkbit
August 2, 2020 5:34 PM
Reply to  William Quade

thank you William, I’ll have that in mind if I can’t get an american version.

Darkbit
Darkbit
August 5, 2020 5:52 PM
Reply to  William Quade

do you know of any other chip that will do a japanese ps1 region free to play american games on it? I’ve been told that when you chip a japanese ps1 it will read anything (original and copy games and also original games from any region)

Lucas
Lucas
November 7, 2020 8:45 AM

With this chip, ps1 can read cd-rw? If not, is it theoretically possible someday?

Robert
December 4, 2020 9:30 AM

Hi wiliam,
I have scph-5502 pal, can u help me ,how to chip it?

Robert
December 4, 2020 11:21 AM

If i chiped my spch-5502 pal pu18 as i see in diagram, can i burn imeges on cdr an play all region games in color?

Robert
December 4, 2020 3:26 PM

Thanks William 👌

One more question man ,🙏

Are ther some chip or modifications in motherbord , to fix this problem, if colour problem appear ?

🤙

Robert
December 4, 2020 5:02 PM
Reply to  William Quade

Can I see picture how its looks when it’s done? To do that same my self,
Thanks man ☮

Robert
December 5, 2020 10:41 AM
Reply to  William Quade

comment image

Like this?

Robert
December 6, 2020 5:21 PM

PIC12C508A-04/SM SOIJ8 1.79€
PIC12C508A-04I/SM SOIJ8 1.91€
PIC12C508A-04/SN SOIC8N 2.76€
PIC12C508A-04/P PDIP8 2.11€
PIC12C508A-04I/P PDIP8 2.51€
PIC12C508A/JW CDIP08 16.03€

Witch to choose, to programme mm3?

J Matson
J Matson
December 17, 2020 1:05 PM

What AWG wire do you use for the MM3 mod chips?

Robert
January 20, 2021 7:48 AM

My scph 7502 pal not chiped is blinkink color imedge, what to do, to fix it?

Robert
January 20, 2021 11:50 AM
Reply to  William Quade

Its worked well with original cabels , until now, image is blinkink, what can it be?

Robert
January 20, 2021 12:00 PM
Reply to  William Quade

I tryed on older tv yellow and white plugs ,no wer to plug red one ,an it works well witaut blinking, but in black n white .

Robert
January 20, 2021 2:12 PM
Reply to  William Quade

Ok thank man

Robert
January 20, 2021 3:23 PM
Reply to  William Quade

Look man, i tried on same tv 2 wires conected wit other scph 5502 consol and it was colorfull withaut blinking, it must be a problem scph 7502 console , not in cables

Ale
Ale
February 22, 2021 1:37 AM

Hello! I purchased a chip and installed it on my PM 41 psone and it worked perfectly for about an hour. Now it doesn’t turn on and I checked that fuse PS606 from the service manual is blown. I bridged the fuse and some smoke came out 🙁 but the system still turns on so it might be possible to save it. What could be making the fuse blow up? I checked the soldering points with the guide provided in this page and everything seems correctly placed. Thanks!

Ale
Ale
February 23, 2021 1:38 PM
Reply to  William Quade

Would the position of the soldering points affect this fuse blowing up? I’m unsure if bridging the fuse without the modchip would still destroy the motherboard, or if I should switch the positions in which I soldered the chip

Cosmin
Cosmin
March 7, 2021 6:27 AM

Hello Wiliiam,
After i manage to modchip my SCPH-5502 Ps1 model with PIC12C508A every burned games runs in a grey image.
It starts fine but when the game is loading image is became grey.

Scott Sleep
Scott Sleep
March 14, 2021 6:44 PM

Gday william
My chip wants to work but stops a the playstation screen?
I tripple checked and yes its my first time doin this lol.
Any help wood be good.
Cheers
Scott

Scott Sleep
Scott Sleep
March 15, 2021 6:33 AM
Reply to  William Quade

The lasers brand new

Mike
Mike
May 27, 2021 7:10 AM

Hello, I have a modded ps1 and i wanted to play Pal games on it. But my image keeps moving. Could it be because im using an americant tv? I know they have a different frequence of image in europe so I was wondering if this could be the cause of my problem.

FrontaleBotsing
FrontaleBotsing
June 27, 2021 9:57 AM

Hi, I modded my ps1 SCPH-1002 witha 12c607/p chip. When I insert a copy of a game on a cd-r it will only play it as a music cd… Do you know why this is? Did I mod it wrong or is it a burning problem? Thanks in advance!

razvan
razvan
August 26, 2021 7:30 AM

i think the laser is faulty. had the same problem on a sega saturn, replaced the laser and it loaded backups fine.

John
John
August 4, 2021 9:31 AM

Can I write new code on the PIC12C508A that you sell here? Or you can only write once to it? Thanks

John
John
August 4, 2021 12:10 PM

if I use the AV multi out port on PS1 modded PAL, will it also show output in black and white when NTSC disk is played?