Sega Model2/3 - JAMMA Adapter Thread

[biggestsonicfan]

RESOURCES:

• Sega Model 2 and 3 Filter Board Pinouts

For Sale:

• Sega Model2b to JAMMA adapter - Yahoo Japan (Verified seller by @biggestsonicfan and @Fredo . A proxy service may be required)
• Sega Model3 to JAMMA adapter - Yahoo Japan (Same seller as above)

Original thread post below (it's no longer relevant):

Spoiler: Original Post

For a while, we've had some discussion of Sega Model2 (specifically b/c) JAMMA adapters in the Last Bronx conversion to Sonic the Fighters thread but I feel the need for a separate thread is long overdue.

In that thread, however, user @Tailsnic Retroworks posted their recent acquisition along with a JAMMA adapter I'd never seen before. After making a deal with them, they sent it over to me for potential cloning of the adapter.

The adapter:



The depopulated scans:





High resolution (1200dpi) scans hosted here.


I am currently making a schematic of the amplifier, but I'm afraid I might need help actually getting this board into a CAD program. I'd prefer to CAD this thing in KiCAd, but I'm not sure how how to create the HA13001 part for the layout.

EDIT1: Traces traced and schematic sort of initially laid out:

 

[chacal231077]

Good idea .


it lacks more than an amplified stereo RCA output connectors and not amplify according to its choice. . Me i prefer the audio output directly from the filterboard to the cabinet amplifier

 

[biggestsonicfan]

it lacks more than an amplified stereo RCA output connectors and not amplify according to its choice. . Me i prefer the audio output directly from the filterboard to the cabinet amplifier

Many people prefer that, I'm afraid, myself included. I think what I will do is make a small, very small, run of the adapter with the amp, and then remove the amp and add RCA connections to it instead of an amplifier for an "improved" design.

Anyway, here's what the design looks like thus far:

A big thank you to @Frank_fjs for their Jamma Fingerboards which I converted to KiCad to use as a nicely designed JAMMA edge here!

EDIT: Looking for this connector type. It's unusual to have the single bottom shroud. Thought it might have been a JST, but JST doesn't have that sharp right angle out of the plastic.

 

[biggestsonicfan]

The amplifier circuit is 100% done. Not a fan that the new pot is bigger than the old one but it was closest compatible and in-stock one I could find. The new connector peices came in and they're a lot wider/longer (how ever you want to put it) than the old ones, so I will need to adjust for that. I already did with PWR_BTM there.



What I plan to do next is add the Test1 and Test2 buttons, then the remaining headers and tackle the GND and +5V copper fill before I connect the header connections to their JAMMA edge connections.

I still need to figure out how to properly create edge holes for the HA13001 so it can mount.

 

[biggestsonicfan]

So a while back, @twistedsymphony asked "which games use more than 3 buttons per player?", and I might have an answer now....

While reversing this JAMMA adapter, I noticed both pins "26" and "d" are used, connected to "GUN1" and "GUN2" respectively. As I don't have a House of the Dead machine, I can't verify how this would work with a HOTD setup, but this is something I'm going to need to document somehow if someone ever wants to JAMMA convert (GOD WHY?!) a lightgun machine to be compatible with HOTD.

EDIT: Question: Should the RGB ground and AUDIO- not be connected to the same GND? I think I read that somewhere, and this JAMMA adapter is indeed wired that way, so I can fix that if needed.

 

[biggestsonicfan]

Well, I did connect the RGB ground and AUDIO- to the same GND, oh well. I also noticed a few things on the board that weren't connected previously:

• The JAMMA finger 14 (V.GND) was not connected to anything.... I connected it to common GND.
• TEST1 button was not connected to the JAMMA edge as a bypass if using arcade service buttons.
• TEST2 button was not connected to the JAMMA edge as a bypass if using arcade service buttons.

This is what the board looks like according to the JLPCB preview:



Very excited to see my first complex PCB in person when it's done. I made an order of 5 (smallest order JLPCB allows) and 3 are claimed, so if anyone wants one let me know here, I will have 2 available soon.

 

[Mrhide]

Well, I did connect the RGB ground and AUDIO- to the same GND, oh well. I also noticed a few things on the board that weren't connected previously:

• The JAMMA finger 14 (V.GND) was not connected to anything.... I connected it to common GND.
• TEST1 button was not connected to the JAMMA edge as a bypass if using arcade service buttons.
• TEST2 button was not connected to the JAMMA edge as a bypass if using arcade service buttons.

This is what the board looks like according to the JLPCB preview:



Very excited to see my first complex PCB in person when it's done. I made an order of 5 (smallest order JLPCB allows) and 3 are claimed, so if anyone wants one let me know here, I will have 2 available soon.

i would take one pretty please with a cherry on top !

 

[biggestsonicfan]

i would take one pretty please with a cherry on top !

You have been added to the list for an original amplifier version!

I am intrigued in making a version 2, but can only do so if there's enough interest. Also, if there's enough interest in a version without an audio amplifier, I could make one of those too.

Version two is looking a little something like this so far:

Instead of built-in amplifier with a discontinued amp chip, this runs on Adafruit's MAX9744 board using some PCB spacers and 2.54mm headers. It also includes screw terminals as audio outputs so you can wire them to speakers however you'd like, such as an RCA cable or 3.5mm phono cable to it.

[A few hours later]

I edited the board to make it JUST a direct wire connection to JAMMA using an autorouter with thicker 0.5mil traces:

So that may be an easier, and faster option for me to make as well. It still has the test buttons! But it does NOT have the the Sensor and Gun connectors, because I honestly don't think you should be wiring your HOTD cab for JAMMA, LOL!

So there are some new options, but I do hope to sell the original batch first, as it was the most expensive to build (time and investment wise).

 

[twistedsymphony]

EDIT: Question: Should the RGB ground and AUDIO- not be connected to the same GND? I think I read that somewhere, and this JAMMA adapter is indeed wired that way, so I can fix that if needed.

I missed this edit.

Audio - May or may not be ground depending on the system. you should always check to see if it's tied to ground to confirm if it's balanced (not tied to ground) or unbalanced (tied to ground).

you can cause blown traces, blown amps, or PCB damage if you handle it incorrectly.

with that said, given that this is line-level out from the mobo it's most likely unbalanced (grounded), but still worth verifying!

 

[biggestsonicfan]

EDIT: Question: Should the RGB ground and AUDIO- not be connected to the same GND? I think I read that somewhere, and this JAMMA adapter is indeed wired that way, so I can fix that if needed.

I missed this edit.
Audio - May or may not be ground depending on the system. you should always check to see if it's tied to ground to confirm if it's balanced (not tied to ground) or unbalanced (tied to ground).

you can cause blown traces, blown amps, or PCB damage if you handle it incorrectly.

with that said, given that this is line-level out from the mobo it's most likely unbalanced (grounded), but still worth verifying!

Thanks for your answer. I think you're right. I was mostly worried about introducing noise into the video signal via the common ground, but I don't think that'll be an issue. I wonder how this adapter worked without a video ground

 

[twistedsymphony]

I wonder how this adapter worked without a video ground

weirdly I've seen a lot of JAMMA edges that rely on the harness to provide video ground (usually bootlegs), I don't like it personally. In those instance I think it's safe to just provide the common ground from PCB to the video ground as thats how most PCBs will handle it.

 

[twistedsymphony]

Some design suggestions:

1. If you use JST NH connectors on the input. this is what's used on the filterboards already and I'm pretty sure you can buy pre-crimped JST NH wires so it would make the harness an off-the-shelf part instead of having to make them.

Also consider vertical JST NH headers instead of right-angle. This would have a few benefits. Considering the thickness of a Model 2/3 system you wont really be adding any height over what the stack already takes up and you could seat this PCB closer to the stack since the cables would be occupying the vertical space instead of horizontal. ALSO if the connectors were arranged amicably this would allow you to design daughter-boards that could plug directly in on the top. So maybe you make a plugin IO board to use this with a PC, or a plugin IO board to use it with a JVS system, or something else altogether.

2. Provide a VGA input in addition to the JST NH input. This would serve a few benefits

• on Model 3 units you could use a VGA cable to link up video instead a JST NH harness
• it would more easily open up the usage of this board to other non-JAMMA PCBs
• it would make it much easier to place a video converter board between the model2/3 system and this IO board for those that need to run at 15Khz or 31Khz

3. Provide a pair of RCA audio ports wired in-line with the normal JST NH input. if wired in-line it could act as a line level stereo output (with your PCB essentially doing the conversion from JST header to RCA) OR it could act as an RCA input. giving us that extra option on Model 3, or again for use with some other type of PCB

4. Consider adding a 4-pin JST NH 5V power header (similar to those used on Sega JVS IO boards). this simple addition would allow for this PCB to act as a power pass-through for additional IO boards, such as the aforementioned Video converter. or a Sega Type 1 JVS IO... just adding this and appropriate RA to NH harness would allow the use of this PCB with JVS hardware.

5. I'm not sure how you're handling the Stereo to Mono conversion on the output of the Amplifier but might I suggest using Taito's Stereo over JAMMA setup. Basically they use an amplifier with a Balanced output and then Left+ goes to JAMMA audio + and Right- goes to JAMMA audio -. The result is that cabs that support this setup (such as Egret 29 and Egret II) get Stereo over JAMMA and cabs that don't support it will just naturally merge this into Mono. If you're interested you can see how this plays out in the Cab Harness side: Taito Egret 29 Restoration

Given the weirdness of things like SuperGuns and other people's custom harnesses it might be best to make this switchable between the above and something where JAMMA Audio - is just plain ground, but I'll leave it up to you whether you think either of these things are worth the effort.

6. PLEASE include some screw posts for PCB feet in all 4 corners with plenty of clearance so there's no risk of damaging interference with traces or components. I know people like to make these things as small as possible but I know I'd personally rather have a board like this take up a little bit more space and not have to worry if my connectors will fit or if I wont have any way to mount it somewhere.

 

[biggestsonicfan]

Whew, quite the list there. Let's see if I can address all this.

1. If you can point to a reliable source of JST-NH headers and "off the shelf" cables, I would be thrilled to use them! The Adam Tech connectors I am currently using are SUPER cheap though from Digikey with high stock, but they share the same pitch as the JST-NH headers, so it wouldn't be too hard to change them.
2. I like this idea and will keep this in mind for any future builds.
3. I was looking into this, actually, but this would be for a JAMMA-non-amp adapter setup.
4. Interesting idea. I will also keep this in mind.
5. Ugh, so currently, and I think this is stupid, but one channel goes to the SPEAKER +/- and the other channel goes to COINCOUNTER 1/2. So it is a custom, however, it can produce combined mono output over the single SPEAKER +/- set of JAMMA pins by placing the 4.7K Ohm 5% resistor between pins 2 &3 of the little "MONO/STEREO" header. It was just like this on the original board, and I was making a clone. I don't particularly like this setup but it does the job.
6. While there are 4 3M post screws on the clone board, I admit the clearance isn't the best, but hey, it's what you get when you clone a random possibly Chinese adapter in the first place. But yes, 4 post holes is my goal. I will revise my smaller board to have better clearance and add two additional upper holes.

 

[twistedsymphony]

If you can point to a reliable source of JST-NH headers and "off the shelf" cables, I would be thrilled to use them!

Any JST stuff can be ordered directly from JST: www.jst-mfg.com

I'm not sure if they carry the Pre-Crimped wires but Digi-Key does: https://www.digikey.com/catalog/en/partgroup/nh-series/87280

I was looking into this, actually, but this would be for a JAMMA-non-amp adapter setup.

The beauty is that there is no need for any components between the RCAs and sound input header, so it would work just as well as an input as it would as a pass-through.

Ugh, so currently, and I think this is stupid, but one channel goes to the SPEAKER +/- and the other channel goes to COINCOUNTER 1/2

Is this how the original adapter was setup? that's uh probably not good. Man I can just hear that coin counter clicking away the credits to the beat of music O.o

 

[twistedsymphony]

oh, I just had another thought on #3....

some of the Model 3 boards that used the DSB2 board had an additional little "Audio Mixer" PCB, basically just 3 sets of JST headerss and some resistors, to allow merging of the audio output from the main board and the DSB2 into a single output. If you wanted to be fancy you could find a way to build that into your adapter too.



of course you would only really need to add the second header and the resistors since the output would be fed straight to your amp.

 

[chacal231077]

Too bad we can't invent a Sega Model 2/3 Multi-Filter Board in JVS Hybrid version from the Naomi model
Even if the Video output would be VGA 24khz, the goal is to reduce the video cables, audio and those of the control in usb.

I'm sure it's possible we will be in 2021 soon lol

 

[biggestsonicfan]

If you can point to a reliable source of JST-NH headers and "off the shelf" cables, I would be thrilled to use them!

Any JST stuff can be ordered directly from JST: www.jst-mfg.com
I'm not sure if they carry the Pre-Crimped wires but Digi-Key does: https://www.digikey.com/catalog/en/partgroup/nh-series/87280

With just the 25-pin header alone at a minimum quantity of 200 for $86+, that is way over my budget. I could make so many sets of JST-NH to Adam Tech cables with headers for that price.

They do have all the headers though, but for those prices, it just inflates the cost per adapter so much. Gonna have to stick with ArcadePartsAndRepair for my JST-NH housing needs.

 

[biggestsonicfan]

Too bad we can't invent a Sega Model 2/3 Multi-Filter Board in JVS Hybrid version from the Naomi model
Even if the Video output would be VGA 24khz, the goal is to reduce the video cables, audio and those of the control in usb.

I'm sure it's possible we will be in 2021 soon lol

The idea keeps crossing my mind but I can't really justify the design costs of a PCB that big, lol.

 

[biggestsonicfan]

Alright, so I'm studying the only available Model3 to JAMMA adapter I can find, and unless someone else posts pics of another one, this is the only one i have for analysis.



The JAMMA adapter itself only converts controls and RGBSG as well as a ground from the filter board to the JAMMA adapter.

A second adapter, a 24 pin ATX, powers the 3.3v, 5v, 12v, and GND rails. Obviously not fully JAMMA compliant out of the box.



It appears an option is to also have the GBS attached to the ATX adapter cable for the 5v input, as well as the RGB input JST-NH header leading to the input. The picture doesn't show anything going back to the JAMMA adapter though, but I guess that might be assumed?

Some notes from the translated page:

• Spikeout requires additional wiring for the sound source board.

That's interesting. I really need to know more about Model3 to confidently make my own version of the adapter.

 

[twistedsymphony]

Spikeout requires additional wiring for the sound source board.

yes, this is one of the games that uses the DSB2, and the additional wiring is likely that audio mixer pcb I mentioned earlier as well as maybe some additional power wires for the DSB2 (though it may simply plug power into the Model 3 filterboard) AFAIK the rest of the games that use the DSB2 are all fancy controls, no other joystick/button games. Star Wars Trilogy, Daytona 2, and Sega Rally 2 are some of the other games that use it.

if you don't know what the DSB2 is, it's essentially a second PCB in it's own cage that does high quality music the mobo feeds it signals as to which audio track to play and then the audio output is mixed back into the normal audio output from the main board.