Mahjong -> Jamma adapters (Interest check)

[buffi]

Mahjong PCBs have a real weird pinout which looks basically nothing like Jamma. Voltage pins, video, audio and controls are all different, see:
https://forum.arcadeotaku.com/viewtopic.php?p=120446&sid=d7f05df295c31cda40f019f166ce492b#p120446

I'm currently using a hacked together adapter that looks... not great, and want to replace it with something nicer, so I threw together a PCB design for it that I'll have printed some time soon-ish once I've double checked it, and figured out if I want to change something.

Would there be any interest from anyone else in getting some of these? Would be pretty cheap since there's not really any components other than a JST header.
Dunno how many people are into Mahjong though.

Before:

After (early draft):

 

[buffi]

Not a lot of interest which I guess is not too surprising, so guess this is mostly for me.
Think this is basically done now, so will order it some time this week and then try it out when it arrives at some point

 

[nobody]

Yeah it's a niche product for a niche hobby.

But nice work BTW.

 

[froztbite]

If you order extras I would be interested in getting at least one. Been toying with the idea of making a mini Mahjong control panel and was going to make similar looking adapter from your first post but the new one you designed would be much better solution.

 

[buffi]

Yeah, there's not much difference in cost so I went ahead and ordered 15 of them. I'll let you know when I've tested it

 

[buffi]

First attempt. Some text is a bit too small.
Will try it out in the cab later today to see if I wired it right

 

[djsheep]

I've been meaning to get a Mahjong game.

I have a set in the real world and actually play. Two questions.

1. Is the Mahjong pinout universal amongst all games?
2. What are the definitive Mahjong games for arcade?

 

[buffi]

I've been meaning to get a Mahjong game.

I have a set in the real world and actually play. Two questions.

1. Is the Mahjong pinout universal amongst all games?
2. What are the definitive Mahjong games for arcade?

1. Some games are Jamma with separate outputs for panel. Some have a split pinout on two smaller edge connectors. Most use a standard edge header similar size of Jamma but different pinout.

2. Not sure tbh

 

[buffi]

Well uh… one botch needed but otherwise seems ok

 

[andynumbers]

Hi there! Somehow I missed this thread. I would be interested in these. I am assembling a small collection of mahjong PCBs and could benefit from this.

There are a few bullet points worth mentioning about the mahjong pinout:

Problem: Most mahjong PCBs have a speaker+ connection and no speaker- connection. A common ground elsewhere on the board is used in place of the SPK- connection. However, this is not 100% consistent for all PCBs. Some later PCBs do have a SPK- pin. (Psikyo PCBs I think use this)
It is important to note that most of the time when a common ground is used in place of SPK-, pin#10 is blank.
I have a very early mahjong PCB that has SPK+ on both pins 10 and L! So caution must be used for cases like this.

Solution: some kind of selectable jumper to choose between a common ground and a populated SPK- pin.

Other things worth mentioning:
I haven't encountered one yet, but it's possible there could be a PCB that uses -5v. This would theoretically be on pins B and 24 if used. Maybe include a selectable jumper to route this to the JAMMA -5v pins?

Mahjong control pins seem to differ between Sega candy cabs and Egret IIs. Perhaps a solution would be to simply bypass the JAMMA wiring and include a connector on your JAMMA adapter to simply plug a mahjong control panel straight into your adapter, bypassing any non-standard JAMMA mahjong pinout. I have 4x Egret II mahjong panels and I can get you the Egret II specific pinout for these controls if you want it. Aero city seems to be totally different where the harness just goes straight to the control panel directly. Astro and blast I'm not sure on but I think it's similar to the Aero where the JAMMA internal control wiring is simply bypassed.

Anyway, that's my two cents. Hope you are able to make something out of it!

 

[buffi]

Solution: some kind of selectable jumper to choose between a common ground and a populated SPK- pin.

Extremely helpful suggestion. I think having an actual switch to bind either jong SPK- or common GND to jamma SPK- should be worth it. Should fit fine. Thanks a lot for that suggestion.

Maybe include a selectable jumper to route this to the JAMMA -5v pins?

Yeah, I might see if I can add a jumper or at least two bodgewire testpoints on the bottom of the pcb for this.

Perhaps a solution would be to simply bypass the JAMMA wiring and include a connector on your JAMMA adapter to simply plug a mahjong control panel straight into your adapter, bypassing any non-standard JAMMA mahjong pinout

This is already on there
If you look on the pic above, theres an unpopulated JST connector for exactly this usecase. Theres silkscreen lines for where to cut if you also want to disable the connections to jamma side.

I couldnt find any info on jamma panel wiring for inputs (Astro City which I use seem to only use external connectors), so I just routed COM ports to P1 and KEY ports to p2 to allow making my own wiring for panel connectors->panel. Will finish that up and show what I mean later.

Would be happy to send you one of these when I have the next revision done (changes mentioned here + fix video gnd which I forgot to route in v1)

 

[buffi]

I’ve been testing it on Psikyo pcbs and Jaleco games btw which use spk- and spk+, so very good to learn about those differences!

 

[buffi]

This works pretty well for my Psikyo games, but will make a v2 that does the changes mentioned above.

To clarify a bit how the panel wiring works, it requires making a separate cable to connect the panel to the cabinet wiring like this

This will repurpose p1 and p2 controls as Mahjong COM and KEY

The other option is to connect the cables to the connector on the adapter. I like that less though, so I have that unpopulated (right in pic)

 

[buffi]

Bigger text, SPDT Switch for Audio (Jong SPK- or GND to Jamma SPK-), Unpopulated jumper for -5V.
Gonna do some minor cleanups and then order some.

 

[andynumbers]

So if I'm looking at this correctly, your control pinout is specific for your net city setup. Would you be willing to make different versions of this adapter for different control pinouts? I'm envisioning two possibilities here:

An Egret II specific version: The Egret II MJ panel follows this very oddball pinout located here: https://andynumbers.files.wordpress.com/2015/04/pinout.png (just pay attention to the "MJ function" and "Jamma function" rows in this picture)
One thing to note is that "button 6" is an external connector on the Egret so you'd need to have a JST YL pigtail hanging off the adapter. Also, you can leave off theoretical 2P keys on this adapter since that would never be used in this case.

Sega Naomi JVS to JAMMA IO pinout: For the whopping 3 or so mahjong control panel games that run on Sega Naomi, there is a standard pinout used on the Sega JVS to JAMMA IO board that makes more sense than what the Egret did. The pinout is simple: http://psikyobabble.com/pics/misc/Mahjong_Multiplex_NAOMI_Type-X.JPG
The "keys" just go in order starting at JAMMA pin 17 (1P start) and go down in order to JAMMA pin 22. The "coms" are on a separate output 14-pin JST NH connector, so you would want to put this connector on your JAMMA adapter.
Anyway, it may make more sense to base a "generic" mahjong to JAMMA adapter on this particular pinout since it would potentially be something people would already be set up for.

Let me know what you think about this idea. I would be in the market for 4 adapters that are Egret II specific. Unfortunately I don't think I would buy the adapter you already have created since I would have to make mods to it or use the unpopulated header.

 

[buffi]

Once again great comments!

your net city setup

It's an Astro City, but same panel pinouts I think! In terms of pins I used on the adapter, I just went with something that felt like it made sense.

An Egret II specific version: The Egret II MJ panel follows this very oddball pinout located here: https://andynumbers.files.wordpress.com/2015/04/pinout.png (just pay attention to the "MJ function" and "Jamma function" rows in this picture)

That's some odd decisions though! I really wonder why they insisted on just using P1 controls and non-jamma standard pins, especially when not even fitting all pins in there.

Sega Naomi JVS to JAMMA IO pinout: For the whopping 3 or so mahjong control panel games that run on Sega Naomi, there is a standard pinout used on the Sega JVS to JAMMA IO board that makes more sense than what the Egret did. The pinout is simple: http://psikyobabble.com/pics/misc/Mahjong_Multiplex_NAOMI_Type-X.JPG

This makes way more sense though, and I should probably change my adapter to something closer to this. It seems weird that it only uses COM keys on the externa IO port though and not KEY as well, since they should all fit there. I might change my KEY pins to be compatible (very minor change), but will keep COM ports as P2 as well.

The "keys" just go in order starting at JAMMA pin 17 (1P start) and go down in order to JAMMA pin 22. The "coms" are on a separate output 14-pin JST NH connector, so you would want to put this connector on your JAMMA adapter.

If I were to replace my external connector with a JST NH instead, it would be fully compatible with this setup. A 14 pin JST NH has a slightly awkward (long) footprint though, but I'll look into that! It's a good idea!

Let me know what you think about this idea. I would be in the market for 4 adapters that are Egret II specific. Unfortunately I don't think I would buy the adapter you already have created since I would have to make mods to it or use the unpopulated header.

Not sure on the Egret 2 compatibility. Its a weird pinout for sure

 

[andynumbers]

It seems weird that it only uses COM keys on the externa IO port though and not KEY as well, since they should all fit there. I might change my KEY pins to be compatible (very minor change), but will keep COM ports as P2 as well.

There's not enough room for all keys to fit on that connector because the first 3 pins and the last 3 pins are reserved for additional +5V and GND connections.

Some more food for thought: "Keys" are inputs, just like regular button inputs on a standard JAMMA. "Coms" are "outputs", kind of like having multiple isolated common grounds. Outputs can't exist on a PCB's JAMMA connector (such as the JVS to JAMMA IO), so they have to be moved to a dedicated external connector. It's also worth noting that for the JVS to JAMMA IO there is a jumper that selects the function of that external connector. The pins can function as inputs for 6-button fighters, or outputs for mahjong and other oddball non-jamma games.

 

[buffi]

Outputs can't exist on a PCB's JAMMA connector (such as the JVS to JAMMA IO), so they have to be moved to a dedicated external connector

Yeah this makes sense I guess for the JVS IO. I mean bidirectional pins are a thing but I get why they did it like that.

Since NH connectors should mate ok with NH headers with less pins, I might just jam two separate six-pin NH connectors as external connectors instead of the one I have there now, and have them follow the same order as Naomi. Then a cab suited for Naomi should slot right in plug&play (ignoring the NH KEY header).

 

[buffi]

Since NH connectors should mate ok with NH headers with less pins, I might just jam two separate six-pin NH connectors as external connectors instead of the one I have there now, and have them follow the same order as Naomi. Then a cab suited for Naomi should slot right in plug&play (ignoring the NH KEY header).

Went ahead and did this

 

[twistedsymphony]

I've got a small collection of Mahjong games. Ive never actually got around to hooking up a panel on any of my JAMMA cabs though (just JVS because it's plug and play)

one issue I see with this board this is that it's a straight through connector and a whole lot of Mahjong games already have a right-angle adapter for the Mahjong edge. this include those games on Jaleco Mega System 32, Sega ST-V, Aleck 64, SSV and other systems



There right angle adapter like this seems a lot more common than boards with a Native MAJAN* pinout
once you have an additional straight through adapter on there it's sticking straight up and could cause fitment issues with a lot of cabs (certainly mine)

*Both Aruze and Kaneko refer to the Majong edge as a "MAJAN" I don't know what it stands for nor have I found any official documentation but thats the closest I've found to a name in the same vein as "JAMMA"