Konami GX (System GX)¶
Konami's high-end 2D/2.5D base (1994): a 68EC020 + big sprite/tile customs, in Types 1 to 4 (including dual-screen versions). Sexy Parodius, Salamander 2, Tokimeki Memorial, Run and Gun… The base of the GX converts.
Identification¶
| Field | Value |
|---|---|
| Manufacturer | Konami |
| Year | 1994 |
| Type | 2D/2.5D (zoomed sprites, effects) |
| Variants | Type 1 / 2 / 3 / 4 (Type 3/4 = dual monitor / DMA) |
| Settings | EEPROM / DIP |
Architecture¶
| Block | Chip | Role |
|---|---|---|
| CPU | Motorola 68EC020 (@ ~24 MHz) | game logic |
| Sound | K054539 (+ sound 68000) | PCM samples |
| Video | Konami customs (K055673 sprites, K054156/K053936 planes, zoom/rotation) | rich 2.5D, "Mode 7" effects |
The System GX pushes 2D with rotation/zoom (K053936 "Mode 7") — hence the warped
backgrounds of Racin' Force or Run and Gun. Type 3/4 handle two monitors
(dual-screen) or advanced DMA. Emulated in MAME (konami/konamigx.cpp).
Conversion & swap¶
The System GX allows game swaps with care (reinit the EEPROM by holding TEST at power-on); ⚠️ orientation differs by Type 1/3/4. → Konami GX / Viper converts.
EPROM repair: 68EC020 program on the ROM board, often 2× 27C040 → game-by-game EPROM table.
Notable games¶
Gokujō Parodius / Sexy Parodius, Salamander 2, TwinBee Yahho!, Daisu-Kiss, Tokimeki Memorial, Run and Gun (Slam Dunk), Lethal Enforcers II, Racin' Force, Konami's Open Golf Championship, Soccer Superstars, Dragoon Might, Fantastic Journey, Winning Spike…
Common faults¶
| Symptom | Likely cause | Lead |
|---|---|---|
| Corrupt sprites/planes | GX customs / RAM | RAM test, contacts; rare customs |
| No sound | K054539 / sound 68000 | Sound-stage diagnosis |
| 2nd screen dead (Type 3/4) | dual-screen output/harness | Check the 2nd output |
| Lost config | EEPROM / battery | Reinit (TEST at boot); see converts |
| No image | Power, 68EC020, contacts | Base diagnosis |
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). A leaking battery corrodes traces — check and replace it before it leaks → save batteries.
- Storage 🟡: the game lives in EPROM/mask ROM on the board. Changing or restoring a game means reprogramming the EPROMs (and, for a mask ROM, using a pinout adapter) → EPROM method.
- Media preservation: replacing the original storage, multicarts, ODEs and modern options by family → PCB preservation hub.
- Scan rate 📺: ~15.62 kHz / 59.2 Hz — standard resolution, a classic 15 kHz chassis is fine → tri-sync and upscalers.
(Computed from the MAME sources —
konami/konamigx.cpp— pixel clock ÷ htotal.) - FPGA / emulation: see the Emulation & FPGA section below.
Repair (technician)¶
- Game swap = EEPROM reset: a GX booting to an error after a swap may need an EEPROM reset (held procedure), not a repair.
- Konami customs (K055673 sprites, K054156/K053936 zoom/rotation planes): corrupt = **RAM
- buffers first**, the custom next (donor).
- Sound: sound 68000 + K054539 — diagnose the sound stage.
- Capacitors: recap. ROM-board type per game (see converts).
→ 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 | 8 MHz | main CPU |
| M68EC020 | 24 MHz | main CPU |
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.
Original manuals for games on this platform ✅¶
Manufacturer manuals for games running on this board. Beyond the instructions, they very often carry the full DIP settings, the connector pinout, the test procedure, the parts list and the expected voltages.
- Lethal Enforcers II — original manual (PDF)
→ Full catalogue: service manuals, wiring & game manuals
DIP settings ✅¶
8 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 ggreats2
| Setting | Position | Options (default in bold) |
|---|---|---|
| Select Connector | SW1:4 | 3P 4P · 1P 2P |
DIP settings — MAME set le2
| Setting | Position | Options (default in bold) |
|---|---|---|
| Stereo | SW1:1 | Stereo · Mono |
| Coin Mechanism | SW1:2 | Common · Independent |
| Stage Select | SW1:3 | No · Yes |
| Mirror | SW1:4 | No · Yes |
| Flip Screen | SW1:5 | Off · On |
DIP settings — MAME set le2j
| Setting | Position | Options (default in bold) |
|---|---|---|
| Stage Select | SW1:3 | Yes · No |
| Mirror | SW1:4 | No · Yes |
DIP settings — MAME set opengolf
| Setting | Position | Options (default in bold) |
|---|---|---|
| Sound Output | SW1:1 | Stereo · Mono |
| Coin Slots | SW1:2 | Common · Independent |
| Number of Players | SW1:3 | 2P · 4P |
DIP settings — MAME set puzldama
| Setting | Position | Options (default in bold) |
|---|---|---|
| Flip Screen | SW1:3 | Off · On |
DIP settings — MAME set racinfrc
| Setting | Position | Options (default in bold) |
|---|---|---|
| Flip Screen | SW1:3 | No · Yes |
| Cabinet | SW1:4,5 | 2in1 · Upright (Mono) · Unused · Upright (Stereo) |
| Car Number & Color | SW1:6,7,8 | No. 1 (Red) · No. 2 (Blue) · No. 3 (Yellow) · No. 4 (Green) · No. 5 (Red) · No. 6 (Blue) · No. 7 (Yellow) · No. 8 (Green) |
DIP settings — MAME set tokkae
| Setting | Position | Options (default in bold) |
|---|---|---|
| Cabinet | SW1:4 | Upright · Vs. Cabinet |
DIP settings — MAME set type3
| Setting | Position | Options (default in bold) |
|---|---|---|
| Sound output | SW1:1 | Stereo · Mono |
| Left Monitor Flip Screen | SW1:2 | Off · On |
| Right Monitor Flip Screen | SW1:3 | Off · On |
| Number of Screens | SW1:4 | 1 · 2 |
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
Procedure — a dead board, step by step ✅¶
What this adds
The general method lives in PCB diagnosis. This is its application to this platform: the same order, but with the values actually expected here, so you do not have to go back and forth.
Tools: multimeter, oscilloscope (or frequency counter), current-limited bench supply, desoldering braid. → Tooling
If the board is still in a cabinet
A CRT holds its charge with the machine unplugged. → CRT safety
1. Inspection, power off. Corrosion, cut tracks, oxidised EPROM legs, leaking SMD capacitors, dubious earlier repairs.
2. The connector, before anything else. A large share of "dead boards" are a contact problem, not a fault. Clean the contacts with isopropyl alcohol and reseat — not with an abrasive eraser on a gold edge, which takes the plating off and brings the problem back worse. It costs two minutes and settles the question.
3. Power, measured on the board. Aim for +5.0 V measured as close as possible to where power reaches the board — not at the PSU output: the drop is in the loom, and that is exactly what makes a board boot on the bench and not in the cabinet. Where you probe depends on this board's connector — JAMMA edge, JVS loom or a proprietary harness — plenty of makers kept one long after JAMMA arrived — see Identification above. → Wiring Check −5 V and +12 V too if the sound stage uses them. Suspected short: bring it up current-limited and find the hot spot.
4. /RESET. It must release after power-up. Held low = the CPU never starts. A 1–2 Hz loop is not the reset circuit, it is the watchdog: the CPU is crashing at boot, so look at the bus, not at the reset.
5. Clocks — the values expected on this platform.
- M68000 → 8 MHz (Main CPU)
- M68EC020 → 24 MHz (Main CPU)
No clock on the M68000 (8 MHz) and there is no point measuring anything else: the fault is the crystal, the divider, or the chip itself. That single measurement splits a dead board in two.
6. Bus. Activity on the main CPU's address lines tells you whether it is running or frozen. Frozen with good clocks and good reset → work RAM, bus buffers, ROMs.
7. It boots but the picture or the sound is wrong — that is another job: see Common faults on this page, then signal tracing.
Emulation & FPGA¶
- Emulation: MAME (
konami/konamigx.cpp). - FPGA / MiSTer: no confirmed dedicated core → MAME.
Lineage¶
After the 68000 beat-em-up era; for 3D, Konami moved to the Hornet (PowerPC) then Viper. For 573 security: see System 573.
Photos / assets¶
(To add: GX Type 1/3 board, sprite customs, K054539.)
Sources & attribution¶
- MAME —
konami/konamigx.cpp(68EC020, K054539, K055673/K053936, Types 1-4, games) — https://github.com/mamedev/mame - Internal page: Konami GX / Viper converts
- Wikipedia — Konami GX — CC-BY-SA — https://en.wikipedia.org/wiki/Konami_GX
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.