PU-18 Mayumi v4 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 Mayumi v4 chips click here, for more information about PS1 modchips click here.

PU-18 Mayumi v4 modchip installation diagram

MM3 chip pinout


PU-18 Mayumi v4

Above is the diagram for the PU-18.

All of the points are fairly easy to solder to, with the only tricky point being pin one. Just don’t apply too much pressure or you might knock the capacitor off of the board.

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.
  • The high speed clock line (pin 2) needs to be especially short and carefully routed.
  • Placing the chip in between the circles for pins 3, 5, and 6 seems to be the ideal location.
  • Flatten the legs of the chip so it can more easily fit underneath the board.

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.

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.

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December 14, 2018 8:38 AM

About to install this one… thanks for the chip. A few recommendations though… please pre-bend the leads on the chip so they are flat then cut the skinny parts off, then solder the wires to them when selling them pre-wired. Shrink wrap leads afterwards, if needed. Ship them in ESD safe bags, instead of regular plastic ziplocks. Thanks again for offering them for sale.

December 19, 2018 4:42 AM

Hi i want to now if you send the chips olso to the nederlands i think not or

September 1, 2019 1:59 PM

I used this guide to install my chip and di so quite successfully but it’s playing imports in black and white. PAL region games play in colour fine though.
What’s the deal, how do I fix it?..

September 1, 2019 2:52 PM

Did this install but imports are playing in black and white.
PAL games are still playing in colour though.
Anyone know how to fix this?

November 15, 2019 7:18 AM

For some reason dino crisis can sense my modchip. I have even tried all the modes. Is this normal? I’ve been installing mayumi v4s for years on both pu-20 and psone models no issue.

March 3, 2020 4:16 AM

Hi there =) Did the mod with a success [SCPH-5502 PAL], i first thought my chip [PIC12C508A] was bad because it wouldn’t boot but i found out that it was a motor problem from my cd drive and some of my backup cds i used wasn’t compatible (bad CD-R). The only small problem i crossed is that the chip can go out of sync during the boot, blocking at the PS Logo Black Screen and during playing (the cd don’t get read anymore, can be from my drive tho and only happened once on Yu-Gi-Oh! F.M. trying to get to… Read more »

Peter Jensen
Peter Jensen
May 29, 2020 4:06 PM

it didnt work for me? now my ps1 wont even play normal games? it just loads up to the memory card screen, but I cant do anything, anyone know what went wrong?

Peter Jensen
Peter Jensen
May 30, 2020 4:54 AM
Reply to  William Quade

oh Im sorry, I forgot to reconnect the lazer cable, my bad 😉 the chip works fine