Redgun project (SCART To JAMMA Adapter 3)

[viletim]

For those unfamiliar, the SCART To JAMMA Adapter is a product I created several years ago to make it easier to play game consoles on a JAMMA arcade cabinet. It had built in video and audio amplifiers, as well a controller expansion connection to attach additional controller interface boards. The only controller board that ended up getting released (aside from basic terminal blocks and JAMMA pass through) was a Playstation 1/2 interface.

I still think there is merit in this idea so I decided to have another go at it. This time I've split the project it half. One part handles analog audio and video for CRT arcade monitors, the other part in the interface for the controls. Each part will be available separately and do not depend on each other for operation. In the future, most arcade machines will contain LCD or similar flat panel displays, making the video part less relevant.

The video section is just about ready for production. The prototype is pictured below. The RGB video amplifier is identical to the previous version. A television jungle IC has been added to the design which decodes composite video, s-video, and component. There is a comb filter for the composite video. The video inputs are auto switching. There is a simple user interface with led display and buttons to set up the video related parameters like which signal goes over which input, colour control, comb filter disable, etc.

The audio amplifier is a class D design which is now in stereo instead of mono like the previous version.



There's only one RGB input but it can be increased to four with this four input automatic SCART switch. It was originally intended as an accessory to the Framemeister. It's small enough to be stuck to the the top without blocking the labels and buttons.




These two (Redgun-video and SCARTMUX) are about ready for production and I intend to submit the files to factory before the end of the month.

The next part is the controller interface (Redgun-JAMMA). This is still in the preliminary stage of development. It mounts on top of the Redgun-video board as shown in the photo. The board contains a JAMMA connector, a big microcontroller, an SD card interface for software updates, an audio amplifier (redundant), and a serial bus connection called RG-bus.



Then there are the controller pods. This is a small, lower cost board that sits between the console and the (main) Redgun-JAMMA board. The pod implements the actual controller interface and receives new data from the main board continuously at a fast rate (about 500 hz refresh rate). The pod I have in the photo below should be capable of implementing any pre-USB protocol, with software updates loaded from the main board.



The general idea is you have one controller pod for every console you want to keep permanently attached to the arcade cabinet. The consoles are stored outside the cabinet (eg. on a shelf beside it) for easy access to change games. The cable management is reasonable because the controller cables between the controller and the pod are very short and the RG-bus cable is light weight telephone cable. The pods are connected in a daisy chain. Here's photo showing two consoles connected to the Redgun-JAMMA board.



The Redgun-video board should be available by April. For those that intend to used it by itself, does it needs a kind of mini JAMMA adapter board to interface power/video/audio and break out the controller wires into a ribbon cable? Or is this not necessary?



I'm also looking for general feedback at this point. Do you find this concept interesting? More for the controls or the video part?

[emphatic]

Looks wonderful.

[andy251203]

Count me interested. I've been interested in this for years now. I bought one of the last JAMMAcon devices by Shane Kiely when that was still available, but I'm always interested in a quality Tim Worthington product.

One idea for the redgun video board is that you could use it as a video interface to turn an arcade monitor into a TV essentially. Mount an arcade monitor in a TV-like enclosure, add the redgun board and you have a TV. Not sure if anyone would want to use it this way, but if you happen to have spare arcade monitors lying around it's one possibility.

[donluca]

This board is one of the most complete I've ever seen which leads me to an observation:

There are several of us which are looking for a simple, goddamn SCART to Jamma thing which does one single thing: get the video output from SCART, clamp/restore, amplify, done.

Nothing else as lots of us already have a cab wired for stereo with our own amplifiers and already have our own solutions for the controls.

It's clear that you're aiming for a solution which does it all (and then some), but I'm pretty sure that the price will be quite high (and rightfully so), too high for people like me (and many others) who are looking just for a solution to hook RGB up to Jamma.

May I ask if you're going to provide a simpler, bare bone solution to convert the RGB signal to JAMMA?

[RGB0b]

For those that intend to used it by itself, does it needs a kind of mini JAMMA adapter board to interface power/video/audio and break out the controller wires into a ribbon cable?

Yes. I can definitely see people using this who've already wired an MC Chthulu or similar in their setup. Just a "basic" JAMMA board that plugs on top like the other one would be great.

Also, I can see this being used in CRT's: If this can be wired directly to the tube, this could be another alternative for RGB modding a CRT. I'd definitely like to experiment with this once it's released.

[DirkSwizzler]

I'm mostly excited that you're working on video conversion. The options in the composite and s-video to RGB space are lackluster.

I'm hoping it won't be terribly hard for me to repurpose that board to convert composite and s-video to RGB scart. And possibly the same for component, but at this point I'm assuming any conversion you're doing isn't designed for HD video. And the Garo is already handling that reasonably well for me.

[the Goat]

Super cool project.

[FairWitness]

I have one of your older SCART To JAMMA adapters and it's awesome. Can't wait to see this one materialize as it looks to have a lot of smart additions.

[viletim]

May I ask if you're going to provide a simpler, bare bone solution to convert the RGB signal to JAMMA?

The bare minimum to go from SCART to JAMMA is a video clamp + fixed gain RGB amplifier + sync separator. Probably a SCART connector input and terminal block output. Is that what you mean?

For those that intend to used it by itself, does it needs a kind of mini JAMMA adapter board to interface power/video/audio and break out the controller wires into a ribbon cable?

Yes. I can definitely see people using this who've already wired an MC Chthulu or similar in their setup. Just a "basic" JAMMA board that plugs on top like the other one would be great.

The MC Chthulu board is bit hopeless, but the Brook Fighter and PS360 boards have a 20 pin header that I could accommodate.

Also, I can see this being used in CRT's: If this can be wired directly to the tube, this could be another alternative for RGB modding a CRT. I'd definitely like to experiment with this once it's released.

It's not really good for that. A could have added the features required but it would have added more cost and delays for something almost nobody wants.

I'm mostly excited that you're working on video conversion. The options in the composite and s-video to RGB space are lackluster.

I'm hoping it won't be terribly hard for me to repurpose that board to convert composite and s-video to RGB scart. And possibly the same for component, but at this point I'm assuming any conversion you're doing isn't designed for HD video. And the Garo is already handling that reasonably well for me.

You would be able to wire a SCART cable to the output terminal block. The RGB signals are compatible when the contrast control in in the centre position and the sync just needs a series resistor. There are even some (crappy) arcade monitors out there which have their inputs terminated with 75 ohm resistors. It's all strictly SD/15 khz video only.

[BuckoA51]

Cool idea, I bet places like Arcade Club here in the UK would be interested in this.

[donluca]

May I ask if you're going to provide a simpler, bare bone solution to convert the RGB signal to JAMMA?

The bare minimum to go from SCART to JAMMA is a video clamp + fixed gain RGB amplifier + sync separator. Probably a SCART connector input and terminal block output. Is that what you mean?

That's *exactly* what I was looking forward.

After dumping money on several projects which all yielded very poor results I got fed up with it and called it a day and waited for someone to come up with a proper solution.

Ideally what I'm looking forward, in laymen terms, is a scart connector on one side and whatever thing with R G B S signals on the other one. Heck, even solder pads would be fine to keep costs down as I'd still have to hook it up to a jamma connector.

[mtn360]

Definitely interested in the whole package. I'd likely want to put a PCE, MegaDrive, Amiga 600 and SNES into one of my cabinets first.

[mR_CaESaR]

Yay! I've been waiting for this for a while since I wanted another version 2, but could no longer find any.

The MC Chthulu board is bit hopeless, but the Brook Fighter and PS360 boards have a 20 pin header that I could accommodate.

If you're not too far from me, I'm more than happy to lend you a Brook Universal Fight Board for testing.

I don't suppose you have indicative pricing on the production boards do you? I'd imagine with the jump in features from the v2, the price point will be more than what the v2 sold for?

[mikaeltarquin]

Is this project still active? I'm extremely interested in buying basically the whole package.

[8bitForLife]

I would like to know also.

[Hasuki-san]

sounds amazing, so fingers crossed that it will be available for buying and shipping sooner than later. Keep us updated, we are all interested !

[buttersoft]

Another awesome project. People gatekeep and complain about rising prices, but the energy in the retro space is great AFAIC, and you've always been a big contributor, Tim

[viletim]

Is this project still active? I'm extremely interested in buying basically the whole package.

Yes, I'm working on it and I've made some changes since the first post. I'll have an update in a couple of weeks.

[P.H.U.]

I came into the arcade hobby right as your SCART2JAMMA 2.0 went OOP. Been waiting for 2+ years for your SCART2JAMMA 3.0. But now that I have acquired tri-sync cabs (New Net City) that allows me to quite easily connect my consoles to a cab, see what you have in store, and my own DIY explorations into the subject, I'm pretty much out of the market and won't be buying it.

I love how you added component video transcoding though. Being an American, it is the best possible way to get video from an unmodified Wii. But to be quite honest, the only unique title in the Wii's library that lends itself to play on a cab is TvC. I have some critiques to your design if you want to hear them. If not, I'll just keep them to myself. But I can say that most of them echo what donluca has stated. He and I have had numerous discussions on this over on arcade-projects.com.

[psykom1]

I've been lurking on your projects forever as I had bodged my own scart to jamma adapter together a while back.
This all-in-one solution is really sharp.
I look forward to seeing this come to fruition.

[P.H.U.]

Hey Tim,

Based upon previous discussions over on arcade-projects.com and what is stated in this thread. Seems there are two camps:

• Those that are totally onboard with what you have planned.
• Those that feel what you have planned is too ambitious.

No need to discuss the sentiments for those that are totally onboard with what you have planned. They'll be fully supportive of what you will produce once it comes out. For those that feel it is a bit too ambitious, here is a wishlist:

1. What you have solutioned for the A/V from consoles is more than we require. But is fine as is.
2. Multi-console PCB's with the 20-pin header have become the standard for controlling consoles with arcade parts, so.....
   • In addition addition to your fully planned Redgun-JAMMA board, how about producing an alternate lite version, which would include just the following:
     • Two 20-pin multi-console headers for installation of two multi-console PCB's
     • Optionally, screw terminals for those that still like pad hacks
     • A CPS2/3-style kick harness housing

Many potential buyers of your solution have already invested in multi-console PCB's and would like to use them along with your Redgun-video module. Having to buy the JAMMA module fully populated would be redundant for those of us that have multi-console PCB's.

Question about audio output. Given there shall be 3 types of cab users when it comes to audio:

1. Pure JAMMA audio people
2. JAMMA cab owners that shall rewire for stereo
3. Cab owners with stereo amps already

What is your current audio output design on the Redgun-video module? For Pure JAMMA audio people, they would need amped mono. JAMMA+ cab owners would need line-level stereo from either a 3.5mm stereo jack or preferably from female RCA's to connect to their stereo cabs. JAMMA cab owners that will rewire their cabs for use with your solution need amped stereo. Can you elaborate what audio outputs you have available. It's not clear from the info you've put forth so far?

Lastly, here is a suggestion. Probably too late in the cycle for implementation. But I'll suggest it anyway. Add a VGA connection capable of amping a 15khz hacked VGA signal (using Calamity's drivers) and combining separate H/V sync into Csync from that VGA connection to your design. I feel in doing so, you would open your solution up to MAME users, increasing your potential market. I say this because I have been using the J-Pac for a long time. I find that the amp in the J-Pac isn't very good with contrast. I see the market for the J-Pac is ready for disruption. I feel if you do this, MAME users can leverage your onboard audio amp. A feature that the J-Pac doesn't have. Also, the J-Pac uses keyboard emulation which has its own limitation. If you do produce a lite version of the Redgun-JAMMA board, the multi-console PCB's do have the ability to interface to a PC. So what you would end up with is a solution that taps into the niche market for arcade hobbyists that will interface consoles to cabs and you'll tailor your device for the MAME crowd which is much bigger than the console-to-cab niche. I think that would be pretty cool and would be offer a tremdous value for those MAME ppl that would have never otherwise thought to have interfaced their retro consoles to a cab. Then would add value for console to cab guys too. Don't do it if you don't think there is any gain for you $$$-wise.

EDIT: An HD15 video input helps a ton with the much older consoles too.

Also curious what IC you decided to use for the video amp?

Appreciate your work Tim. Let me restate I am on the fence on this. Not out of the market yet.

[crocky]

Love this!

I had a few questions:

1. Will auto-switching have a safe operation if more than one consoles are on or do we need to be extra cautious?
2. Since the board is software updateable can we expect it to run every console (controllers) from A2600 to X360 eventually some day?
3. Do you have a tentative date of launch in mind?


Cheers

[viletim]

Here's what the current version of the JAMMA board looks like.



The differences are that I've added a video section and made changes to the controls section. There's now a CPS2 kick harness header on the board, along with a 10p IDC box header which is connected in parallel. It supports 8 inputs. Typically 3 player1 kick buttons, 3 player2 kick buttons, 2 volume -/+ buttons.

The way the RG-bus works is different now too. I won't go into too much boring detail - basically all the brains has been moved into the pod. This has makes the JAMMA board cheaper and the pod more expensive, but will speed up software development time. The SD card socket is inside the pod now. The pod also has the volume -/+ buttons.

The idea of the pod is to get the controller interface close to the console which should be external to the cabinet. The RG-bus is a real bus, and can accept multiple controller pods connected in a daisy chain. It can also be quite long, tens of meters is fine. If you connect two pods to the bus and turn both consoles on the second one to come on will detect traffic on the bus and stay silent until the first one is turned off.


donluca,
I designed a simple board that is nothing but a fixed gain video amp. I'll have a prototype ready in a couple of weeks.

P.H.U.,
I agree with you about the video hardware. I think most people won't need the big video board.
The fighter boards available are good for their intended market (fight sticks), but have peculiarities which are less than ideal for used in an arcade cabinet. For example they often to require a special button combination held down while plugging in the controller to put the board into the correct mode. This is awkward if the console is not right next to the cabinet. They also have limited or no reprogram inputs.

I do want to support fighter boards and pad/stick hacks. For now it's the only practical way to interface to some modern consoles which require controller authentication. Support for these will be via the controller pod though. This way the fighter board can be power cycled and put into the correct mode under the control of the pod, without the user having to do a silly dance.

All controller functions are programmable by the way. The programming user interface is audio based (like a telephone automated attendant).

There is a stereo amplifier on board. The amplifier output is via the JAMMA card edge or pluggable terminal block. There is a jumper which determines the output type for the JAMMA card edge. The three positions are single channel mono, stereo Neo Geo style, or disconnected. There is a line output via 3.5mm socket which is always active. There's also a dip switch on the board that mixes the stereo input to the amplifier into mono.
At the moment the only hardware I have actually produces is the SCART switch which I have produce 200 of already and are sitting here awaiting finishing and testing. All the rest is still very changeable at this point.

I don't have one, but I always thought the JPAC was a pretty good product for the money, with the only downside being the lack of audio amp. I hadn't heard about the video amp problem before. I agree with you about adding VGA/MAME/PC support would increase the market size, but it adds cost and complexity.

The current controller pod design doesn't support USB. I would be better to design another pod that just does USB for this purpose. And it could be reprogrammed via the PC I suppose.
Also, regarding MAME and 15khz drivers. I haven't followed this stuff for over 10 years, but why are people still combining H and V sync signals together? Can't every video card make a composite sync signal these days? It makes it so much simpler.

Finally, the design of the video amp on the video board is the same as the SCART To JAMMA V2. It's uses an LM1281 VGA monitor preamplifier chip. It has excellent gain and bandwidth. The downside is that it requires a 12V supply - and it better be 12.0 volts exactly, with close to zero noise on it. The PSRR is terrible. It's also requires lots of current and gets quite hot.
The video amp that I put on the JAMMA board is made with high speed opamps similar to those on my AV-Driver board, but four times higher bandwidth. The gain is fixed at 5.7 so would have an output af 4 Vpp normally. It runs from 5V and doesn't use much power.

crocky,
Auto switching works the same way on the SCART switch and the video board. There are two modes of operation. One will switch to the first active signal and not switch again until the signal goes away. The other mode will rank the inputs in order and a higher rank input will take precedence over lower ranking one. None of the inputs are connected together directly, everything is multiplexed.

The current pod hardware is good for all pre-USB consoles with the exception of the Colecovision (can be done, just needs extra hardware).

I can't give a launch date, but I'm working on it full time at the moment. It should be more a matter of months than years.

[donluca]

donluca,
I designed a simple board that is nothing but a fixed gain video amp. I'll have a prototype ready in a couple of weeks.

Amazing! I've been waiting for something like this forever. Even a DIY version (without tiny smd parts if possible! ) would be absolutely fine to me. Just the printed PCB and then we add the connectors, components and whatnot.

[P.H.U.]

donluca,
I designed a simple board that is nothing but a fixed gain video amp. I'll have a prototype ready in a couple of weeks.

Amazing! I've been waiting for something like this forever. Even a DIY version (without tiny smd parts if possible! ) would be absolutely fine to me. Just the printed PCB and then we add the connectors, components and whatnot.

For the simpler version, audio output is also a consideration. Would like to see:

1. Line-level stereo output to 3.5mm jack or female RCA's (at a minimum)
2. Amped mono w/volume control (implemented with #1 above would be ideal)
3. Amped stereo w/volume control (as a nice to have)

Hi Tim,

• I believe the J-Pac uses the MAX4386E amp. Perhaps you have seen it in your travels and know of its limitations. But it does lack contrast, at least in my experience.
  • It's a small concession twisting H and V sync to get Csync for Calamity driver users. Made easier these days with breakout terminals.
• Component/S-video/composite remain as inputs on the Redgun-video module after your redesign, correct?
• Looks like the controller pods connect to controller cables that terminate to DB15 breakout terminals? Is it your intention then that users can make their own controller cables? If so, that would be awesome! Also, I can picture how the pod would work with multi-console PCB's and am gaining comfort with the considerations you've put in.
• Excellent work on the audio design. Zero concerns now that you've explained it further.

So excited about this project again. Been waiting literally years. I'm back on board!

[donluca]

Audio output is not really a priority for me, as I get line-level audio out straight from the board, but I can see why people would like to have it. It could be done as a quick'n'dirty solution with just a diode and some resistors IIRC, but I don't know exactly how amplified audio is done on arcade PCBs and if it needs to be altered in any way.

[Capcomista]

Hi Tim!

One friend of mine has the Scart to Jamma V2, he sent me a video with an explanation on how it works and it looks very interesting. I have a Sega New Astro City cabinet and some Tototek PS2 adaptors for Saturn and other consoles so I would like to know if I can plug 2 PS2 cables to the board to use these adaptors. My main concern goes to the posible input lag on the controls too.

Please Tim, keep us informated about your last udtes on the board, thanks!

[ninjaz0mbie]

This is probably a silly question, so I apologize for my naivety, but does this conversion from SCART to JAMMA happen in real time? Is there any lag introduced? e.g. could I plug in my Sega Saturn and play Virtua Cop?