Works with PM-41 (2) (A); No success with Mayumi 12F629 in a PM-41 (A) PSone

I recently attempted to install Mayumi in a PSone with a PM-41 (A) board using PIC 12F629 and the ported HEX. Even though I double-checked my connections and tested neighboring pins for shorts (none), something was seriously wrong. Before removing the mod and reflowing it would just stay on the white boot screen, even without a disc (never reached the CD Player/Memory Card manager menu). I can be pretty sure this wasn’t related to the chip because it did this even when I snipped the wires to remove the chip.

In the mean time I went ahead and installed another one in a PM-41 (2) (A) board and it worked perfectly. The first board was working fine with original discs after removing the mod wires and reflowing, so I clearly just had an installation fluke. Right? Well, I reinstalled Mayumi in the PM-41 (A), checked all my connections (all good; no neighboring shorts) and this time I didn’t lose the ability to boot originals... but it doesn’t boot backups. The installation was pretty clean with short wires. The chip was programmed back to back with the other working one so it should have been programmed correctly. Even so, I removed it all, read it out, and verified it to the original HEX (checked good).

I decided to try one more time. This time I did it “Voultar style” with pin 13 going straight to pin 2 of the PIC and the PIC mounted on top (super-short traces). Same problem: Boots originals, won’t boot backups. No success with Mayumi 12F629 in a PM-41 (A) PSone despite the same being an easy install on PM-41 (2) (A).

Anyone know what’s going on here? Tips? Tricks? Advice? Thanks!

Pic:

Full res: https://i.imgur.com/EAaZzYi.jpg

 

OK, I've since moved the exact same 12F629 Mayumi 4 chip between two PM-41 (A) and two PM-41 (2) (A) boards. It consistently works on the PM-41 (2) (A) boards and consistently doesn't work on the PM-41 (A) boards. I programmed the original Mayumi 4 HEX to a 12C508A and it worked just fine in both PM-41 (A) boards, so this only seems to be a problem with the 12F ports. I also tried a 12C508A MultiMode3 8-wire on a PM-41 (A), which works. I have not yet tried a 12F629 with MultiMode3 but I suspect it works and my issue is limited to Mayumi 4.0 on 12F629. We will see!

12F629 8-wire Mayumi 4 on PM-41 (2) (A) [works]:

Full res: https://i.imgur.com/V6GTxCO.jpg

12C508A 8-wire Mayumi 4 on PM-41 (A) [works]:

Full res: https://i.imgur.com/OChdXkQ.jpg

12C508A 8-wire MultiMode3 on PM-41 (A) [works]:

https://i.imgur.com/dBUzWDi.jpg

Gallery link:
https://imgur.com/a/GQ2fN49

 

12f508 work fine.

When you say "12f ports" - you mean the 12f629 port. The 12f508 and 12f509 doesn't require porting and work just fine with the original hex.

 

Exactly. AFAIK, 12F508/12F509 were intended to be compatible with the same HEX. I referred to this Mayumi HEX as "the 12F ports" because it's the port to multiple 12F-series chips (12F683, 12F675, and 12F629):
https://assemblergames.com/threads/ps1-mayumi-4-0-12f683-12f675-12f629.54179/

I'm using 12F629, 12C508A, and 12C509A. Until running into the issue with the ported Mayumi HEX on 12F629 I had not downloaded the original Mayumi HEX. Since then I have and it works well on my 12C508A chips in the same PM-41 (A) boards which gave the 12F629 trouble even with the ported HEX. The ported HEX on 12F629 works fine on PM-41 (2) (A) boards, so I know the chips themselves function.