Open MVS

The Open MVS is a kit designed to consolize Neo Geo MV1C arcade boards. It’s made up of a multi-piece 3D printed case, designed to give the feel of an AES home console, as well as the circuitry to add high-quality RGB video and stereo audio via a Genesis 2-style output connector. It’s almost entirely plug and play, with only two very easy wires required to solder.

The goal of this project is simple: To provide the retro gaming community with a cost-effective way to safely consolize their MV1C; All video and audio outputs are the proper voltages and 100% safe to use with all SCART equipment. It’s also an option for people to fork the project and implement their own changes. Hopefully this will also reduce the amount of glued-together, poor-quality solutions often found on eBay for astronomical prices.

The files are available for download on their Github / Thingiverse pages and RetroRGB will be hosting the original design here as well:

Main Files:

Board & Circuit files:
Github – https://github.com/tianfeng33/O-MVS
Direct – http://retrorgb.com/assets/openmvs/OMVS_2021-03-13.zip
OSH Park – Front Board / Rear Board

Case Files:
Thingiverse – https://www.thingiverse.com/thing:4792013
Direct – http://retrorgb.com/assets/openmvs/OMVS_v1.0_RC.7z

Compatible RGB and Component Video Cables:

Any properly-built Genesis 2 RGB cable is compatible with the Open MVS’ circuitry. This includes RGB SCART cables, HD Retrovision and RAD2x cables. All links can be found here: https://www.retrorgb.com/genesisrgbcables.html

Power Supplies:
3-Prong:  https://www.digikey.com/en/products/detail/mean-well-usa-inc/GST25A05-P1J/7703645
2-Prong:  https://www.digikey.com/en/products/detail/mean-well-usa-inc/GSM25B05-P1J/7703501
Wall Wart Style:  https://www.digikey.com/en/products/detail/triad-magnetics/WSX050-4000-R/6165629

More about the project:

3D Printed Case

The case in the Open MVS was designed by Avram from TaiToc Labs as a way for anyone with a large format 3D printer to make their own. A printer that can handle 300×300 millimeter prints or larger is best, however you might be able to make one with a 250x250mm printer.

The case is made of a different few pieces and will take quite a long time to print, but is absolutely an option for do-it-yourselfers. There’s also a basic plexi piece in the kit that can mount underneath the MVS logo, however you can place whatever you’d like there.

Circuitry

The internal boards and circuits were designed by Tianfeng and inspired by his previous work on the Sega Triple Bypass and Omega MVS replacement boards.

The front board connects to the MV1C’s JAMMA output and breaks out all the necessary signals. The controller ports, power button and test menu button are available right from there as well.

The power circuit breaks out to a DC input jack, which is compatible with many 5v power supplies.

The video signals are broken out from the JAMMA connector and sent to a rear board that integrates the same proven, tested circuitry Tian used in the Omega MVS replacement board. RGB video output is properly shaped to match a Genesis 2’s and sync is available on both the composite video (as 75ohm csync) and csync (as TTL like the Genesis 2) pins. This allows it to be compatible with every properly-made Genesis 2 cable on the market.

The audio board is the only soldering required during installation, but it’s just two simple wires. This allows for filtered stereo audio instead of mono, which is a great upgrade when used in a home environment. Also, the filter used isn’t too aggressive, so you still get the grittiness you’d expect from Neo Geo games, while filtering out some noise you might not have heard in a noisy arcade, but would definitely notice on decent home speakers.

The other reason for the audio mod is power: The JAMMA standard includes both 5v and 12v power rails, but the MV1C only uses the 12v for audio. Integrating the complete audio circuit on the AV board means 12v isn’t required at all. This makes the power circuit much cheaper and easier to integrate. It also allows for a fully external, international AC to DC power adapter!

Motherboard (MV1C) Preparation

There’s a few mods you should perform to the MV1C before installing the Open MVS kit.

First, replace the battery with a new, socketed design that lays flat on the motherboard. If you’re just using the motherboard as-is without any other mods, you could just leave it snipped, but I really don’t like removing functionality from a board, and I suggest adding the socket that comes with the kit.

As a note, the battery itself has to be a rechargeable one, such as an LIR2032, or ML2032. Definitely do NOT use the non-rechargeable kind!!

Next, you’ll need to address the heatsink, to fit in the case. This is attached to the audio op-amp, which will not be used at all in this kit; The power lines aren’t even connected, as 12v isn’t being used. There’s a few methods you can use to make everything fit:

- Remove the heatsink and desolder the op-amp
- Remove the heatsink and carefully bend the op-amp on its side.
- Remove the heatsink, carefully bend the op-amp on its side and replace it with a smaller heatsink that will fit in the case.

If you think there’s a chance you might use this in an arcade machine at some point in the future, it’s recommended that you bend the op-amp, so it’s there if you ever need it. The model used (STMicroelectronics TDA7240A) is no longer made and if you remove and lose it, you might not be able to find a replacement.

Lastly, solder the two wires needed for the L & R audio channels. These will run to the new audio amp on the rear board.

Other Notes

I’d always recommend doing a thorough visual inspection of the motherboard before completing the install, just to see if anything else needs to be addressed.

Also, you can take this opportunity to install a UniBIOS, VMC, or clockgen mod.

Main Files:

Other Links:

More about the project: