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“HDMI for Neo Geo MVS” is not one universal product. It can mean a direct digital modification that taps video and audio inside the arcade board, the current DIY NeoPico-HD project, or a conventional RGB-output MVS connected to an external scaler. The best choice depends on your exact motherboard, audio wiring, soldering ability, display, and whether you value reversibility over an integrated HDMI connection.
What an MVS normally outputs
Neo Geo MVS hardware was designed for JAMMA arcade cabinets, not televisions. Its native picture is RGB with sync in the 240p class, normally leaving through the JAMMA edge or a consolization/supergun board. Audio arrangements vary: cabinet wiring may provide amplified or mono-oriented audio, while a properly designed consolization circuit can provide attenuated line-level stereo.
Signals available at the JAMMA connector are not the same as the digital signals inside the board. Video and audio are converted to analog by the MVS before reaching many external interfaces. A direct HDMI modification taps those digital buses before the relevant DAC stages; an RGB setup sends the analog output to a scaler.
The NEO-JAMMA supergun documentation specifies 240p output, RGB adjustment potentiometers, sync conditioning and separate audio options, and notes that an HDMI television needs an external upscaler: NEO-JAMMA supergun documentation.
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- [Inputs RGBs or AV] Switch to AV input if abnormal RGBs display occurs. Compatible with Neo Geo CD and Neo Geo AES.
- [Aspect Ratio Switch] Switch HDMI output between 16:9 wide screen and 4:3 square screen.
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What “direct digital HDMI” means
A direct mod does not first convert the MVS to composite, component or ordinary analog RGB. It captures the internal digital pixel data, reconstructs an HDMI-compatible timing, and can embed digitally captured audio in the same HDMI stream.
- Advantages: no extra analog conversion stage, integrated audio, and firmware control over line doubling, timing, scanlines and color processing.
- Risks: board-level soldering, revision-specific tap points, power and grounding requirements, HDMI signal-integrity problems and the possibility of damaging custom chips or traces.
- Important limitation: digital capture does not guarantee untouched reproduction. Color conversion, pixel aspect ratio, DARK/SHADOW handling, scaling and timing remain design decisions.
The 2015 FPGA project
The project that closely matches the original phrase “HDMI Audio and Video for Neo Geo MVS” was a 2015 FPGA implementation, not a universally available retail product. Its author tapped MVS video and audio before the DACs, used RAM for scan doubling, converted audio for HDMI, and inserted audio data islands into the HDMI stream.
The report describes an MVS refresh of approximately 59.1 frames per second, a 720×480p-style output, optional scanlines and roughly 100 microseconds of processing delay. A television rejected an early timing until it was adjusted, while a monitor accepted it. The author also noted small differences in some shadow effects. These are observations from that implementation, not specifications for every later MVS HDMI design. See the original project report.
NeoPico-HD: the current open-source approach
NeoPico-HD is a separate, current project using an RP2350B Raspberry Pi Pico 2 (the 48-GPIO variant) to capture MVS digital video and I²S audio before the DACs and generate HDMI.
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- Line Doubler HDMI – Kaico's SEGA Saturn & Sega Genesis HDMI Adapter for Sega consoles with support for RGBS and Composite outputs.
- All in One Cable - The Kaico HDMI Converter supports Megadrive/Genesis 1 & 2, Sega Mega CD, Sega 32X, Neo Geo CD, Neo Geo CDZ,Neo Geo AES, & Sega Saturn console.
- The Kaico SEGA Genesis HDMI Adapter and SEGA Saturn HDMI Adapter is a plug-and-play device, requiring no additional software or hardware installation.
- Regional Use - The Sega Genesis AV cable is compatible with Sega Genesis, Sega Saturn, and Neo Geo systems in Europe, America, and Japan, ensuring seamless connectivity across regions.
- Includes All Cable Attachments – Comes with 3 additional add on cables for use with Saturn, Megadrive 1, Megadrive 2 and Neo Geo CD & AES
Documented capabilities
- Working 480p HDMI video with 60-fps capture.
- Experimental exact-clock 720p output; the project warns that this timing is non-CTA and needs broader sink testing.
- RGB555 capture and DARK/SHADOW inputs, with parts of shadow processing still described as experimental.
- 48-kHz HDMI audio.
- An on-screen display for resolution, audio and color selection.
- UF2 firmware releases, including the MVS asset named
neopico_hd_mvs.uf2.
Hardware and installation requirements
- A compatible Neo Geo board; MV1C is the board explicitly identified as tested in the repository.
- An RP2350B Pico 2, HDMI connector and wiring to the documented GPIO.
- A mandatory common ground between the MVS and Pico.
- A clean +5-V supply to the HDMI connector.
The repository provides a build workflow based on the Pico SDK: export PICO_SDK_PATH=/path/to/pico-sdk followed by ./flash. Use the current README and source for pin assignments, tap locations and dependencies rather than copying an old diagram.
Earlier development discussion mentioned roughly 20 wires and a custom PCB under development; those comments describe prototype work, not a guaranteed assembled retail kit. The project is DIY/open source, not confirmed plug-and-play hardware. See the development discussion at Raspberry Pi forums.
Board compatibility comes first
“MVS” covers many motherboards. An MV1C guide cannot be assumed to fit MV1F, MV1FZ, MV2F, MV4F or another revision. Digital tap locations, audio routing, available signals and power arrangements can differ.
- Read the exact silkscreen model and revision on your board.
- Match that model to the project’s current installation documentation.
- Confirm video taps, I²S points, ground and power before ordering parts.
- If no verified guide exists, use a professional installer rather than adapting an MV1C diagram by guesswork.
For conventional consolization, the Jamma Nation X guide also stresses board-specific audio and encoder wiring.
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- Outputs 1080p – This SEGA Megadrive / Genesis HDMI Adapter outputs a crisp 1080p signal for full compatibility with modern HD and 4K TVs. Also works seamlessly with the SNK Neo Geo CDZ, AES, and supports add-ons like the Mega Drive 32X and Mega CD.
- Aspect Ratio Switch – Allows the user to output the 1080p image in either 16:9 format or 4:3 depending on the user’s preference.
- Wide Console Compatibility – The Kaico SEGA Megadrive / Genesis 1080p HDMI Adapter supports all Megadrive / Genesis consoles across European, Japanese, and North American regions, as well as the SNK Neo Geo AES, CDZ, Mega Drive 32X, and Mega CD.
- S Video Output – The Sega Megadrive / Genesis 1080p HDMI uses the S Video output from the Saturn console for the most vibrant and clean display output possible.
- 12 Months Support, Repair, and Replace Warranty with Kaico on all HDMI adapters
Audio is not “just another JAMMA pin”
Never feed an unknown MVS audio point directly into a television, scaler or capture card. Depending on the board and harness, the signal may be amplified, mono-oriented, insufficiently attenuated or unavailable from the JAMMA edge when the board is powered only from +5 V. Some arrangements require +12 V for audio circuitry or a pre-amplifier tap.
The NEO-JAMMA documentation distinguishes direct stereo from JAMMA-derived audio and specifies different power arrangements. NeoPico-HD avoids that analog path by capturing I²S before the DAC, but it still requires correct power and common-ground wiring. A line-level stereo output from an adapter such as the Arcaniac MVS-to-JAMMA adapter is not the same thing as a complete HDMI solution.
Direct HDMI versus RGB and an external scaler
| Approach | Signal path | Strengths | Trade-offs |
|---|---|---|---|
| Direct digital HDMI | Internal digital video/I²S audio to HDMI | Integrated output, short digital path, configurable timing | Invasive, revision-specific DIY work; display compatibility varies |
| RGB supergun or consolization plus scaler | MVS analog RGB/audio to external scaler | Modular, serviceable and easier to replace | More hardware; analog levels and sync must be correct |
| Composite or S-Video conversion | Low-bandwidth analog encoder to scaler | Simple on some builds | Lowest image quality for pixel-focused MVS use |
| CRT/PVM/BVM | Native RGB arcade-style display | Original signal presentation | Suitable displays are scarce and require maintenance |
| FPGA recreation or modern platform | Separate hardware reproducing Neo Geo behavior | No vintage-board modification | Not the same physical MVS; authenticity and compatibility vary |
The modular route is often the safer default. The NEO-JAMMA project outputs 240p and expects an external upscaler. Suitable scaler classes include OSSC, GBS-Control/GBS8200 and RetroTINK products, provided the source levels and sync are compatible.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choosing a scaler or interface
| Option | Published price signal (18 Aug 2026) | Best use | Qualification |
|---|---|---|---|
| NeoPico-HD DIY | About $5 was discussed for the RP2350B board only | Experienced builders wanting integrated HDMI | Not a confirmed complete kit; excludes PCB, HDMI hardware, wiring, tools and labor |
| RetroTINK-4K Pro | $750 | High-end RGB processing and extensive controls | Requires a suitable analog source; price from the official page on that date |
| RetroTINK-4K CE | $475 | Lower-cost 4K-class processing | Requires suitable RGB/component output; see the CE announcement |
| RetroTINK-5X Pro | $325 | Midrange analog scaling | Documentation notes possible sync issues with Neo Geo AES; do not assume every MVS setup behaves identically |
| RetroTINK-2X Pro | $139.99 | Composite, S-Video or component sources | Not a natural raw-RGB MVS choice without additional conversion |
Prices are dated snapshots, not permanent prices. Product details are available from the RetroTINK catalog, 4K Pro, 5X Pro and 2X Pro pages.
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- The SEGA Megadrive/ Genesis 1080p HDMI Adapter supports all Megadrive / Genesis consoles across European, Japanese, and North American regions, as well as the SNK Neo Geo AES, CDZ, Mega Drive 32X, and Mega CD.
- This SEGA Megadrive/ Genesis HDMI Adapter outputs a crisp 1080p signal for full compatibility with modern HD and 4K TVs.
- Video Output Mode: 1080P HDMI. Video input Mode: RGBS. Support input resolution: 240p, 288p, 480p, 480i, 576i, 576p.
- The Aspect Ratio switch allows the user to output 1080p images in either 16:9 format or 4:3 format depending on their preference.
- Hassle Free! Easy to use, plug and play with well-prepared cables. - Needs an extra micro-USB cable (included in the box) for power supply.
Installation planning and safety
- Identify the motherboard before buying a board, harness or installation service.
- Use ESD precautions, magnification and a temperature-controlled soldering setup.
- Photograph the board and document every wire; use removable connectors and strain relief where practical.
- Verify supply voltage, current capacity and whether the chosen audio path needs +12 V.
- Provide the HDMI interface’s required +5 V and tie grounds exactly as documented.
- Test with the intended television, monitor, scaler and capture device before final enclosure work.
- Avoid trace cuts or irreversible changes unless the verified guide for that exact revision requires them.
Troubleshooting by symptom
No HDMI image
Check common ground, HDMI +5 V, connector wiring, firmware selection, board revision and every digital tap. A missing ground or unsupported tap can produce a completely dead output.
Image appears, but the television says “no signal”
Try a known-compatible monitor or scaler, then use a documented 480p mode before experimental 720p. HDMI sinks differ in EDID and accepted blanking. NeoPico-HD’s 720p mode is explicitly non-CTA and not guaranteed on every display.
Audio is missing or distorted
Confirm that the firmware and I²S wiring match, that the audio source is digital or correctly attenuated, and that you have not connected amplified JAMMA audio to a line input. On conventional builds, verify the board’s required power rail and audio routing.
Wrong colors or missing shadows
Recheck RGB555 wiring, color selection and DARK/SHADOW connections. Shadow behavior is an identified experimental area in NeoPico-HD and differed slightly in the historical FPGA project.
Intermittent drops or Pico resets
Inspect power stability, ground resistance, solder joints, HDMI strain and short circuits. Separate firmware, wiring and display variables by testing one known-good configuration at a time.
Which route should you choose?
Choose direct HDMI when
- Your exact board is verified, especially if it is the documented MV1C target.
- You can perform fine board-level soldering or pay a specialist.
- Embedded HDMI audio and no separate scaler matter more than reversibility.
- You accept open-source, development-stage caveats and display testing.
Choose RGB plus a scaler when
- You want a modular setup that is easier to replace and repair.
- You prefer a non-destructive or reversible installation.
- You already own an OSSC, RetroTINK, GBS-based scaler or similar device.
- You want to isolate MVS board work from HDMI timing and display troubleshooting.
Use a professional modder when
- The board is rare, valuable or already difficult to repair.
- You cannot positively identify the revision or read board-level schematics.
- Reliability and warranty-backed workmanship outweigh DIY savings.
Bottom line
For a supported MVS and an experienced builder, NeoPico-HD offers the most direct modern path: digital video and I²S audio captured before the DACs, 480p HDMI, and an experimental 720p option. It is not a universal, plug-and-play accessory. For most owners prioritizing serviceability and predictable troubleshooting, a properly wired RGB supergun or consolization board feeding a quality scaler remains the more practical solution. Whichever path you choose, verify the motherboard, audio level, power rails, grounding and display timing before applying power.
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