Recreating mod chip designed for the Playstation 1.

[Katcher]

So before I begin I apologise if I've posted this in the wrong section and for the size of the attached image. This just seemed the best place to ask from my understanding.

I'm looking to recreate a modchip as close as possible to one I bought, and accidentally threw out , from Obscure Gamers a year ago. Sadly that site shut down and the seller pointed people to ASSEMblergames, a site of which the mods and admin have seemingly abandoned making it impossible to sign up to as it requires them to authorise your account after email verification. This has made communication incredibly difficult to purchase a new one and rather than trying to find another seller I've decided to try and recreate the modchip myself.



All I know from this image (and from memory) is the fully assembled modchip is a 15mmx15mm (or 20mmx20mm) PCB with 8 solder points(if the image isn't clear enough the 4 on the left are labelled 1 to 4 from bottom to top and 5 to 8 top to bottom on the right) that connect to each pin on the chip used and a SMD component unknown to me. One of the big issues with recreating this chip is trying to figure out what chip is being used(or usable equivalent that is able to be programmed with the right Hex File required for my SCPH-5552 PAL PlayStation), trying to figure out what that other SMD component is and what it's purpose is, and how to program the chip. Having never created a PCB before now, advice on how to create one would be nice not only for this but for also any future projects.

My reasoning for wanting to recreate the modchip this way instead of finding one from another seller is solely down to how it's presented. It's nice and elegant and a much better solution than just taking a chip, soldering wire to each leg, then soldering the other ends to the correct points on the PS1's motherboard. Any help is appreciated and hopefully I've made enough sense and if this was posted to the wrong place...sorry.

[KL27x]

There's 99.9% chance that "the chip" on there is a microcontroller which needs to be flashed with a program you don't have.

If the reason you want it is because it is on a breakout board rather than having to dead bug, then you would be better served to buy the mod chip from someone else and put it on a breakout board. You don't even have to make your own. You can buy a breakout board for practically every chip package out there right off eBay for maybe a dollar or 2.

[james_s]

I modded my Playstation about 20 years ago, the mod chip was a PIC12 microcontroller using firmware I found online. I'm pretty sure I no longer have that firmware but it should still be out there somewhere, maybe here. https://assemblergames.com/threads/tutorial-making-your-own-ps1-modchips.55904/

[Katcher]

I modded my Playstation about 20 years ago, the mod chip was a PIC12 microcontroller using firmware I found online. I'm pretty sure I no longer have that firmware but it should still be out there somewhere, maybe here. https://assemblergames.com/threads/tutorial-making-your-own-ps1-modchips.55904/

I've been looking at that tutorial. It doesn't provide the file I need though I did I look around for a PIC12F508 specifically after taking another look at that tutorial and found what I was looking for from Microchip as a SOIC package. If I get a bunch of those that just leaves me with with the question of what that second component in the image is and what it's purpose is. Does it need to be there? Would I risk damaging something if I forgo using it?

[mikerj]

The second component looks like a MLCC capacitor, probably just 100nF for supply decoupling.

[james_s]

This looks like it should work for you.

https://assemblergames.com/threads/ps1-modchip-hex-pack-v2.66568/


What second component? It's been a long time, but it seems like there was only the PIC when I did it.

[Katcher]

The second component looks like a MLCC capacitor, probably just 100nF for supply decoupling.

Nice to know my hunch was right on that just on looks alone. Now all that's left is figuring out how it all connects together, creating a schematic then creating a PCB. Any wisdom you can enlighten me with?

This looks like it should work for you.

https://assemblergames.com/threads/ps1-modchip-hex-pack-v2.66568/


What second component? It's been a long time, but it seems like there was only the PIC when I did it.

There is a MLCC capacitor below the PIC. Thanks for the link though. It's got the Mayumi v4 Hex I need for my model of PlayStation.

[james_s]

When I installed mine I just soldered kynar wire to the pins of the Pic, stuck the IC to a convenient spot with a dab of hot glue and then soldered the wires to the proper spots. I didn't use a PCB, there was only one component. A decoupling capacitor is probably not a bad idea but in my case it works without it.

[Katcher]

So I managed to throw together a PCB using EasyEDA that looks similar to the one I'm trying to recreate. One thing I'm not entirely sure of is where I should be connecting the decoupling capacitor to the PIC12F508. Right now I have it connecting to pin1(VDD) and pin8(VSS). To me it seemed to make the most sense. I am probably wrong as balls though.

[james_s]

Yes it goes between the power and ground pins, so that's right. That layout is bizarre though, why wouldn't you rotate the IC 90 degrees so all the pads just line up directly with the pins they connect to? Then you can put the decoupling capacitor directly next to pins 1 and 8 that it connects to and not have those huge long thin traces between the cap and the IC. That's precisely why those pins are used for power and ground. The whole point of a decoupling capacitor is to put it as close to the IC as possible, minimizing any inductance.

[Katcher]

I honestly have zero idea how any of that even works. I'm just recreating the original mod chip like in the image. It's also the only way things will fit on the PCB. I could bring the location of the microcontroller down a little further if that might help?

[james_s]

Is there a reason the pcb needs to be that exact shape and size? The fact that someone else made it that way doesn't mean you have to. Personally rather than reinvent the wheel I think I'd just buy a SOIC prototyping board, you can get them for under a buck from China.

[Katcher]

Is there a reason the pcb needs to be that exact shape and size? The fact that someone else made it that way doesn't mean you have to. Personally rather than reinvent the wheel I think I'd just buy a SOIC prototyping board, you can get them for under a buck from China.

Space. It's going to be attached to the underside of the PU-18 motherboard around where the EJECT button of the console is when looking it it from above. The smaller the better. The initial square design is much easier to compact if needed where as a more rectangular shape resulting from the pins facing the left and right wouldn't be if I want to make the pads as easy to solder to as possible.

11x11mm Modchip PCB design:


Funky Space Invader looking PCB(Approx. 14x11mm):


The design of the third one is a bit Space Invader looking down to eliminating as much unneeded space. I'm also using a new lib(that is what it's called right?) for the PIC12F508-I/SN I'm gonna be using which appears smaller than the one I used at first. I'll need to update the first and second designs with that one if it is. Considering the size of the entire PCB and given how close things are anyway with the layout I prefer, do I really need to worry about it as much?

[KL27x]

Don't make the pads so big. Bigger != better. The size of wire you are going to be soldering to them is probably 30AWG solid. The pad you want is maybe 50 mil by 50 mils. If you have extra space, you are better served to turn it into extra clearance around the pads. If for no other reason, this is easier on your eyes when you install it. Looking at a sea of shiny solder blobs, it is taxing to try to see a tree for the forest.

Also in this square design, you have no clearance between pads and traces. This is bad. The soldermask is not going to perfectly align with the copper, and the default soldermask opening is slightly larger than the pad*; you can make a board where you can solder a wire and the end of the wire ends up touching the edge of the trace or plane that is running alongside, peeking under the misaligned soldermask.

Around hand solder pads, I try to make clearance at least 20 thousandths on a rigid board, and I like even more if there is unused space. 

*If your software allows to change the size of the soldermask, and you wanted maximum strength of the pads to reduce risk of delamination through multiple reworking, you could make the pads as large as possible but leave the soldermask openings the aforementioned 50 mil by 50 mils. But not all software allows for that.

[Mr. Scram]

You called and they listened. Some background on how it works.

https://hackaday.com/2018/11/05/how-the-sony-playstation-was-hacked/

[Katcher]

Don't make the pads so big. Bigger != better. The size of wire you are going to be soldering to them is probably 30AWG solid. The pad you want is maybe 50 mil by 50 mils. If you have extra space, you are better served to turn it into extra clearance around the pads. If for no other reason, this is easier on your eyes when you install it. Looking at a sea of shiny solder blobs, it is taxing to try to see a tree for the forest.

Also in this square design, you have no clearance between pads and traces. This is bad. The soldermask is not going to perfectly align with the copper, and the default soldermask opening is slightly larger than the pad*; you can make a board where you can solder a wire and the end of the wire ends up touching the edge of the trace or plane that is running alongside, peeking under the misaligned soldermask.

Around hand solder pads, I try to make clearance at least 20 thousandths on a rigid board, and I like even more if there is unused space. 

*If your software allows to change the size of the soldermask, and you wanted maximum strength of the pads to reduce risk of delamination through multiple reworking, you could make the pads as large as possible but leave the soldermask openings the aforementioned 50 mil by 50 mils. But not all software allows for that.

Scotsman here. Not a chuffing clue what mils are. I work in mm. The pads I have are 2x2mm. If that does seem too large I could probably set them to 1.5x1.5mm. Trace width is 0.300mm and I'm not sure what making them thinner might affect. I agree that my trace clearance is shitty. I'm actually in the process of trying to clear it up.

[KL27x]

A mil is a thousandth of an inch. 50 mil is 1.27mm

[KL27x]

Another tip, here. If you are going to have this fabbed, 2 layer board costs just about the same as a SS board. So you can play with vias and whatnot if that makes your pad arrangement more logical (less crossed wires over the top of the pcb when installed. In fact, you could put the pads on the bottom and glue the chip side to the motherboard to make the board dimesions even smaller.*

Also, the thickness of the FR-4 for a board this tiny does not need to be the standard size of 1.6mm. A 0.8mm board would be plenty rigid enough.

*If you wanted to put a silkscreen on the bottom, I would redesign the board so the bottom is the top. And the chip is on the bottom. Manufacturers like the silkscreen to be on the top layer.

[Katcher]

A mil is a thousandth of an inch. 50 mil is 1.27mm

Okay so I've changed the pad size from 2x2mm to 1.5x1.5mm and I'm in the process of re-tracing everything. I'm sticking with 0.300mm thick traces to save potential headaches. I have the decoupling capacitor connecting to pad 1 and pad 8. Pad 1 connecting to the VDD pin on the IC and Pad 8 to the VSS pin. Is there a better way to connect them together. Like connecting the pads to the pins as is but connecting the capacitor to the appropriate traces or vice versa?

Another tip, here. If you are going to have this fabbed, 2 layer board costs just about the same as a SS board. So you can play with vias and whatnot if that makes your pad arrangement more logical (less crossed wires over the top of the pcb when installed. In fact, you could put the pads on the bottom and glue the chip side to the motherboard to make the board dimesions even smaller.*

Also, the thickness of the FR-4 for a board this tiny does not need to be the standard size of 1.6mm. A 0.8mm board would be plenty rigid enough.

*If you wanted to put a silkscreen on the bottom, I would redesign the board so the bottom is the top. And the chip is on the bottom. Manufacturers like the silkscreen to be on the top layer.

I've tried using vias and can't seem to get them wired right so I'm just going with traces on the top layer. As for board thickness I'm settling on 0.6mm though if that's not gonna be rigid enough I'll go for 0.8mm.

[KL27x]

OK, well, if you are using the full featured PCB CAD, you typically "route" your traces rather than drawing wires. You change layers while routing and the via automatically appears. But if you're just drawing copper wires, then I guess it can be trickier.

Another tidbit, here, and a bit of a pet peeve. Complex routing looks cool, but on a tiny board like this, the routing creates a considerable kerf. If you left the board rectangular, V-scoring would save a bit of money in higher volumes.

[Katcher]

OK, well, if you are using the full featured PCB CAD, you typically "route" your traces rather than drawing wires. You change layers while routing and the via automatically appears. But if you're just drawing copper wires, then I guess it can be trickier.

Another tidbit, here, and a bit of a pet peeve. Complex routing looks cool, but on a tiny board like this, the routing creates a considerable kerf. If you left the board rectangular, V-scoring would save a bit of money in higher volumes.

I'm using EasyEDA and only just figured out how to do what you just described with it a minute ago. I'm just gonna stick with how I'm doing it with this design however. Seems to be the simplest option for now. And I'm not really going for complex routing if your on about what I'm wanting to do with the capacitor. I was just wondering if the way I'm connecting it all(Capacitors to Pad 1 and 8 then Pads 1 and 8 to their respective pin) was maybe unnecessary. What's V-scoring though?

[tsman]

Somebody already mentioned it near the top of this thread but your PCB is just breaking out the SMD IC pins to bigger pads and has a decoupling capacitor. You can get SOIC 8 breakout PCBs for very cheap. The decoupling capacitor probably isn't even necessary.

If you're doing this to learn some PCB design then that is fine as well obviously.

[Katcher]

The plan is to recreate the modchip I bought initially. I doubt I could buy a PCB exactly like the one I'm trying to recreate. I appreciate the help but sadly at this point it's moot.

[KL27x]

"Routing" has two meanings here. Signal routing in software is the one thing. But in the other post I was referring to the board outline being routed by a CNC milling bit, vs V-score, which is making a V shaped groove partway through the PCB material. The cost for tab routing isn't really anything to write home about, but the kerf can add up when the board is so tiny. That small difference might mean the difference btn fitting say, 12x18 pieces on the stock sized copper clad they use in a machine, vs fitting 13x19, or about 14% more boards to the same size raw material.

Not that it matters if you are just making 10 board for yourself. Go nuts.

The way you did the capacitor is totally fine, but you could also make a more direct connection for the caps, if you wanted the absolute minimum ESR for your decoupling cap. It really doesn't matter; just a note because you asked.

[james_s]

A decouple capacitor should always be wired directly to the power and ground pins of an IC, as short and direct as possible. In this application it is probably not critical but in things that really need good decoupling those long spindley traces between the IC pins and capacitor would wreak havoc.