SNK Neo-Geo MVS¶
SNK's Multi Video System (1990): the arcade version of the Neo-Geo, with cartridges and multi-slots (the operator loads several games, the player chooses). Unlike the CPS-2, no "suicide": a dead battery loses the settings, not the game. The real danger is battery leakage eating the traces.
Identification¶
| Field | Value |
|---|---|
| Manufacturer | SNK |
| Year | 1990 (Japan, 16 April) |
| System / family | Neo-Geo MVS |
| Connector type | JAMMA (single-slot MV-1) + D-button harness |
| Media | Cartridges (multiple slots) |
| Players | 2 |
| Screen orientation | Horizontal |
| Resolution | 320×224, 3840 colours on screen (65536 palette) |
| Buttons | 4 per player (A / B / C / D) |
Architecture¶
| Block | Chip | Clock | Role |
|---|---|---|---|
| Main CPU | Motorola 68000 | ~12 MHz | game logic |
| Sound CPU | Zilog Z80 | ~4 MHz | drives the sound |
| Sound | Yamaha YM2610 | 4 FM + 3 SSG (PSG) + ADPCM-A/B (samples) | |
| Video | SNK customs (LSPC, NEO-B1…) | 320×224, 381 sprites, 65,536 palette (4096 on screen), sprite scaling | |
| Media | cartridges (slots) | trivial swap, no laser/critical battery on the hardware side |
A very long-lived architecture (1990-2004): late games use huge sprite ROMs, but the 68000/Z80/YM2610 base never changes — hence simple preservation (no suicide encryption on the base hardware).
Multi-slot variants¶
The operator loads several cartridges; the player chooses from the menu.
| Model | Slots |
|---|---|
| MV-1 (and MV-1x…) | 1 |
| MV-2 | 2 |
| MV-4 | 4 |
| MV-6 | 6 |
The single-slot MV-1 is JAMMA (standard cabinet); the multi-slots use the SNK connector + a JAMMA adapter.
MVS (arcade) vs AES (home)¶
MVS and AES (home console) run the same machine code, but the cartridges have a different pinout — deliberately, to stop operators buying the cheaper home cartridges. (Source: Wikipedia.)
Region & UniBIOS¶
Region (Japan / USA / Europe): changes the language, the screens ("Winners Don't Use Drugs"), blood, etc. Set via soft-dips / BIOS.
UniBIOS (Razoola)¶
A homebrew replacement BIOS, the reference tool for Neo-Geo preservation and diagnostics. Version 4.0 = latest official (free for personal use since 2021).
Features:
- Region-free: switch JP / US / EU on the fly.
- MVS/AES mode (arcade ↔ console): changes some behaviours/endings.
- In-game cheats (invincibility, etc.).
- Hardware diagnostics: test menu (RAM, ROM, sprites, sound, controls, colours) — valuable for troubleshooting a board.
- Memory card manager.
In-game menu — one of the combos: Start + Select, Start + Coin, or Start + A + B + C.
Installation: replace the MVS or AES board's BIOS chip (EPROM / flash) with a chip flashed to UniBIOS. (Source: ConsoleMods, RetroRGB.)
The battery / backup (⚠ not a "suicide")¶
The MVS board has a battery (lithium ~3.6 V) that backs up an SRAM (bookkeeping, soft-dips, settings). Major difference from the CPS-2: when the battery dies you lose the settings/counters, but the games still run (possibly a "backup ram error" to clear). No decryption key, no board death.
Battery leakage = trace corrosion
The real MVS scourge: leaking batteries that eat the board's traces (sometimes irreversible damage). Remove old batteries ASAP and replace with a battery holder (3.6 V lithium or coin cell) or a supercap — never leak again.
Repair: corroded traces¶
- Remove the battery immediately (the source of the leak).
- Neutralise / clean the electrolyte: isopropyl alcohol ≥ 90% + brush; rinse well. (Handle with gloves — corrosive residue.)
- Inspect the traces under a magnifier: green/blackened areas are corroded; the solder mask can hide a cut trace.
- Scrape the mask at suspect points, test continuity with a multimeter.
- Bridge cut traces with fine wire (wire jumper), point to point.
- Check continuity, clean, re-mask if possible.
- Fit a battery holder (or supercap) for the future.
The affected traces vary by board / battery location — no universal list. Work by continuity, board in hand.
Common faults¶
| Symptom | Likely cause | Lead |
|---|---|---|
| Corroded traces near the battery | Battery leak | Remove the battery, clean, repair the traces (wire / jumper) |
| "Backup RAM error" | Flat battery / SRAM | Clear via BIOS/UniBIOS; replace the battery |
| Cartridge not read / corrupted graphics | Slot oxidation / cart contacts | Clean the slot and cartridge edge |
| No image / crash | Power, customs, JAMMA contacts | Diagnosis (UniBIOS useful) |
| Settings lost at every power-off | Dead battery | Replace the battery / holder |
Original service manual ✅¶
Manufacturer manual archived locally. It typically carries the schematics, the block diagram, the expected voltages and waveforms, the parts list and the disassembly procedures — the reference when a symptom matches no known fault.
- Neo Geo MVS (MV1FZ) — SNK service manual — PDF
Status
A manufacturer document with no explicit licence, kept for preservation (machine long out of production). Source: Internet Archive.
Recap¶
An MVS board has few electrolytic capacitors (sound/video stage) — the real issue is the battery (corrosion, see above), not the caps. Targeted recap only if sound/video is degraded or a cap leaks. Kits: Console5.
Mods¶
- UniBIOS (see above): region-free, MVS/AES, diagnostics — the #1 mod.
- Consolisation: use an MVS board at home via a supergun or a consolisation case (RGB output + controllers).
- Native RGB: clean RGB output over JAMMA (no mod required).
- Memory card: progress saves on some games.
- Battery holder / supercap: see Repair.
Conversions¶
- Changing game = swap the cartridge (trivial, multi-slots).
- MVS ↔ AES: different cartridge pinout → conversion adapters.
- Multicarts (e.g. "161-in-1"): bootlegs, mentioned for information.
- ⚠️ Do not host ROMs — we describe the method, not the protected content.
EPROM reprog / encryption by game (pre-1999 games = direct reflash; 2000+ encrypted = decrypted ROMs needed): encryption-by-game table.
→ Neo-Geo converts guide (MVS↔AES) · Multi: NeoSD / Darksoft
Modernisation & mods¶
The common ground for every JAMMA board
Video, power, control panel and upscalers depend on the cabinet rather than the board: everything is centralised in Modernising a cabinet. To run the board outside a cabinet (at home, on a display): supergun.
- Battery 🟢: a save battery is fitted (settings/counters/RTC). ⚠️ On this platform, a dead battery does NOT kill the game — it is a leaking battery that corrodes traces. Check and replace it before it leaks → save batteries.
- Storage 🟢: a cartridge system — the modern route is a multi-game cart / flashcart rather than reprogramming, where one exists for the platform → PCB preservation hub.
- Scan rate 📺: ~15.62 kHz / 59.2 Hz — standard resolution, a classic 15 kHz chassis is fine — the most common JAMMA case → tri-sync and upscalers.
(Computed from the MAME sources —
snk/neogeo.h (24 MHz / 4 / 384)— pixel clock ÷ htotal.) - FPGA / emulation: see the Emulation & FPGA section below.
Repair (technician)¶
- Cartridge slot contacts: the No. 1 cause of MVS faults (missing graphics/sound, crashes, freeze) → carefully clean the slot connector and the cartridge fingers (eraser + IPA). Always try another cartridge before suspecting the motherboard.
- On-cartridge encryption (CMC42/CMC50, SMA, PCM2, NEO-PVC per game): on the cartridge, not the motherboard — an unreadable encrypted game = a cartridge custom, not an MVS fault.
- Sound: Z80 + YM2610 (FM+ADPCM) — diagnose the sound stage; memory card for saves.
- Capacitors: recap (especially single-slot and period PSU). UniBIOS is very handy for diagnosis. Oxidised BIOS sockets: turned-pin socket.
→ Methods: PCB fault-finding · Recap · EPROM · Traces & vias
Expected clocks — measurement table ✅¶
Values extracted from the MAME sources for this platform. On a scope or frequency counter, a clock that is missing or off-value points straight at the crystal, the divider or the chip at fault — the fastest starting point on a dead board.
| Component | Expected clock | Role |
|---|---|---|
| M68000 | 12 MHz | main CPU |
| YM2610 | 8 MHz | FM+ADPCM (sound) |
| Z80 | 4 MHz | sound CPU (usually) |
How to read this table
Several values for one component = several board variants in this family (or several instances of the chip clocked differently). These frequencies are those of the clock signal at the component's input, not of its original crystal — on many boards the clock is divided down from a single master crystal.
DIP settings ✅¶
1 games on this platform, settings extracted from the MAME sources (INPUT_PORTS_START blocks). The Position column gives the switch's physical reference on the board (SW2:!3,!4 = bank SW2, levers 3 and 4) — which is what lets you set it up without the paper manual. Games are sorted by MAME set name.
DIP settings — MAME set kizuna4p
| Setting | Position | Options (default in bold) |
|---|---|---|
| Players | SW:2 | 2 · 4 |
Check against your own board
These settings apply to the game and revision described by MAME. One title may have several DIP sets depending on region or revision, and some systems use soft-dips (settings in memory, via the test menu) rather than physical switches. In case of a discrepancy, the board's silkscreen and the test menu are authoritative.
See also: DIP reference · game manuals
Emulation & FPGA¶
- MAME: mature emulation (MVS/AES, UniBIOS).
- FPGA / MiSTer: the Neo Geo core is a MiSTer flagship (MVS/AES, games loaded from SD, UniBIOS supported) — a very faithful hardware rebuild, including sprite timing.
Photos / assets¶
(To add: MV-1 board, battery/corrosion area, cartridge slot, MVS cartridge.)
Sources & attribution¶
Text (content synthesised here, sources for attribution):
- Wikipedia — Neo Geo (system) (specs, slots, MVS/AES) — CC-BY-SA — https://en.wikipedia.org/wiki/Neo_Geo_(system)
- ConsoleMods — Neo Geo: Universe BIOS (UniBIOS) — CC-BY-SA — https://consolemods.org/wiki/Neo_Geo:UNIVERSE_BIOS_(UniBIOS)
- RetroRGB — Neo Geo UniBIOS v4.0 free for personal use — https://retrorgb.com/neo-geo-unibios-v4-0-free-for-personal-use.html
- UniBIOS (Razoola) — official site — https://unibios.free.fr/
- Neo-Geo Development Wiki — https://wiki.neogeodev.org/
Image:
-
mvs-pcb.jpg— Cyberjobe (Wikimedia Commons), public domain — https://commons.wikimedia.org/wiki/File:Neogeo_snk_pcb.JPG
Review & corrections
How this space is used
Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.
Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.