Need help identifying a 7-wire PIC 12C508 PlayStation mod chip on PU-18/SCPH-5501

I need to move a PlayStation mod chip from a PU-18 SCPH 5501 board to a PU-22 SCPH-7501. It works but the drive is flaky. None of the diagrams I'm seeing online match up with this so pulling up the appropriate diagram for the PU-22/SCPH-7501 is going to be tricky unless someone here can help me ID it.


Full rez: https://i.imgur.com/PYOyiaq.jpg

I buzzed it out and the one going straight to the chip is connected to the pad usually connected to PIC 12C508 pin 3, but it's connected to pin 7 here. Sure enough, pin 3 is connected to where pin 7 should be. It looks like that's the only difference from, say, a MM3. Any idea why these pins are swapped?

It boots Legend of Dragoon so I assume it is a stealth chip. Actually, I'm missing Disc 1 but it boots Disc 2 up to the point where it tells me to insert Disc 1 and it also boots a backup of Disc 1 (I didn't patch it but perhaps my source did).

This PlayStation came with a Bung Multi Xchanger that I bought so the mod could be from around the time that Bung was selling the MGD^3 series.

 

My guess is that it's simply a badly installed MM3. Pin 3 normally connects to the X1/X2 speed control line from the mechacon MCU and pin 7 is the door switch. Since pins 1, 8, 5 and 6 are correctly connected, the chip would still at least somewhat work, but the stealth feature would be broken.

I would try installing it in the 7501 exactly as you would for a standard MM3 and see if it works.

 

Thanks. Before checking back in this thread I installed it into the PU-22 SCPH-7501 system with pins 3 and 7 backwards (as they were in the previous console) and it booted my Legend of Dragoon Disc 1 backup... but I got the anti-piracy screen (unlike the PU-18 SCPH-5501 system).

Doesn't this confirm that stealth was working with this screwy pinout on the PU-18 SCHP-5501 install? Any reason why it would work on that one and not on the newer one? Going to sleep now but I'll try switching them back in the morning.

 

OK. I lied: Instead of going to sleep I tried swapping the two pins and installing like an MM3. It still doesn't pass the anti-piracy check where it was passing in the original system with the flaky drive and reversed 3-7 pins. Weird. Oh well. I'm giving it to a friend who moves out of state tomorrow so he'll just have to deal with patching a few games.

Still curious what this is!

 

The definitely suggests that it was working before - and that the chip isn't an MM3. It's also certainly possible that the chip simply doesn't have the code to handle the PU-22 board and up. The reason that the MM3 will work on both the old (<= PU20) and the new (>= PU22) boards is that it's specifically coded to detect which board it has been installed into and select the correct stealth mode for it. If the modchip is not coded to do this then trying to install it like an MM3 is not going to work - the PU22 wiring for the MM3 wires the pin that used to be X1/X2 to another signal on the CD mechacon chip called XLAT that indicates when the MCU is sending a command to the CD DSP - and unless the code in the modchip is written to handle this you are going to get a chip that boots but stealth mode doesn't work.

 

Thanks for your help. He'll just have to live without stealth, I guess. I'll be ordering more PIC 12C508s so that I can do all of my other systems.

Very strange that it doesn't fit any of the pinouts I can find but I don't really have time to see if the hex is protected. Sounds like it's going to have obsolete code anyway. Thanks!

I switched the 3 and 7 again (back to the wonky pinout I received it in) and reassembled. Tried Legend of Dragoon Disc 2 (original) and Legend of Dragoon Disc 1 and they both triggered the anti-piracy screen. It definitely seems that stealth only works in the earlier board.

I'm sure he's going to be happy with it anyway and the installation is now MUCH better than it was. Thanks!

 

https://imgur.com/a/6MlbM

The install matches MM2. They basically even used the same colours as this install diagram. This has partial stealth which may explain why it didn't work.

Also, I suggest you get 12F508 instead of the one-time-programmable C variant. Any hex files meant for 12C508 will also work on 12F508. If you have a bad flash, it's no big deal to simply reprogram it.

 

Thanks. I did a lot of searches for MM2 installation diagrams and could not find that for PU-18 and newer. Found a lot of links to forums that required memberships to see. Bah! Thanks again. I guess there's no point to an MM2 diagram for the newer revision boards so it's no wonder I didn't find anything when searching for those.

Thanks for the suggestion. I saw some reports of 12F508 being kind of problematic when used for PSX mods (inexplicably working in some consoles and not others even without reflashing). The price of 12C508 is cheap enough that I figured the write-once part isn't a big deal. I'll get some of each to play around with. I may even have some old 12C508 PICs around from doing Wii mods BITD.

 

That link I sent you above has the install diagrams for all boards up to 9000. Honestly though, if you're going to be programming some new chips, you might as well just throw away an MM2 and burn a new MM3 one.

12F508 is fine. I doubt you will have any issues that couldn't arise from using 12C508, but that's your call.

 

Thanks!

It was a going-away gift for a coworker who moved out of state Sunday, hence, why I needed to move it and MM3 wasn't an option. I didn't have time to order chips so I decided to move that chip to a better-working console.

I had ulterior motives:
I needed an excuse to meet up outside of work to get my other stuff back and it needed to be enticing enough that he wouldn't just ignore me, hence, the cobbled-together modded PlayStation (he had expressed interest in the past). He had already worked his last day and avoided coming by my office, no doubt because he forgot to bring the SNES games he was borrowing from me (International Superstar Soccer, Super Street Fighter II, and Sunset Riders). He did send me a FB friend request so I wasn't too worried that he'd duck out on me but things were down to the wire. Our employer does not allow me to meet/befriend non-management associates outside of work due to my position, which is why I only contacted him through FB after his last day.

Worked! He's in Florida with a free modded PS and I got my SNES games back. I've got several more PS consoles (repaired three more yesterday) so I'm not sweating that at all.

 

Yeah, I totally get reusing MM2. Even if stealth doesn't work, it'll still work for like (just guessing) 95% of PS1 games. Glad you got all your stuff back!

 

LOL! I totally didn’t remember this when I started a new thread this morning asking why my 12F629 Mayumi (ported HEX) worked on my SU-41 (2) (A) PSone but not on my slightly older SU-41 (A) PSone. I kept my CLK so short it practically doesn’t exist and did the whole thing Voultar-style (chip-mounted; short wires directly to the chip), so maybe there is something to this story about the flash PICs being more particular than the OTP PICs.

I’ll try a 12C509 with the older HEX... like Voultar used. If it’s only particular chip/board combos that are problematic, well, I have another SU-41 (2) (A) and perhaps it’ll work there as well as the last 12F629 + SU-41 (2) (A). I’ll report back!

 

The 12f508/9 work fine, including that code and those consoles.

Can't confirm for the 12f629 port.

 

Can I see what you're talking about when you say "short wires directly to the chip", don't recall seeing a diagram for that.

 

He doesn’t show himself soldering to pin 13 (leg 4 of the PIC) but you can see it there before he slaps on his SOP to DIP adapter. I was using DIP PICs so I had to flip it over, cut the legs, and pain-stakingly trim around the chip to make my connections. He gets VDD for leg 1 of the PIC from pin 2 though it’s a bit easier to get from the capacitor right next to it (show off!).

 

Not really seeing the point if you’re only pulling a few off the IC then having to do all that crap for aesthetics. Usually takes me like 2 minutes to prep and finish a PSone, thanks for the video though.

 

Yeah. His only major point beyond showing off/visual aesthetic is that Mayumi is particularly sensitive to wire length due to relying on the clock signal from the console. Getting CLK from the console is also what makes it boot more reliably than MM3, assuming you get the wire length short enough. His PIC orientation is such that leg 2 is positioned right over the CLK source, minimizing the length of the most important wire. I only did it that way the fourth time so that I could conclusively eliminate wire length as the issue.

 

I've literally never had issues with an MM3 not booting and I've had the same modded PSone for nearly a decade and have modded probably 300 of them or more over that time. What's the source on that as I've heard it repeated here before.

 

MM3 works fine - my guess is that the idea it was unreliable came from people that were using badly written programming software that trashed the oscillator calibration value. In that case, Mayumi would appear to be more reliable since it doesn't use that calibration value and hence overwriting it would have no effect.

 

Thank you for clearing this up, I couldn't ever figure out what people were even talking about over the years. What actually happens, it hangs at the SCEA screen or just reads as a CD-R?