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Namco System 12

The System 11 evolution (1997), still PlayStation-based but more powerful — the base for Tekken 3, Soul Calibur and Mr. Driller. An interchangeable COH board (PS1) + a per-game ROM board, locked by a KEYCUS (CPLD).

Identification

Field Value
Manufacturer Namco
Year 1997 (Tekken 3)
Base Sony PlayStation (PS1, revised)
Structure COH board (PS1) + game-specific ROM board
Security KEYCUS (CPLD KCxxx / MACH211) per game

Architecture (≈ PS1)

Block Chip Role
CPU MIPS R3000A (PS1) game logic
GPU custom Sony (PS1) 2D/3D rendering (more RAM than System 11)
Sound Namco C352 32 PCM voices
Media COH board + ROM board + KEYCUS program flash (2E/2J per revision)

The System 12 has more memory and an interchangeable COH board (PS1 base), hence a more ambitious catalogue than the System 11. Emulated in MAME (namco/namcos12.cpp).

Security (KEYCUS)

Like the System 11, each game has a KEYCUS — here a CPLD (KCxxx, MACH211 type) — plus a program flash (2E/2J). A conversion means handling the target game's KEYCUS, which is very hard (CPLD patch). → System 11/12 per-game KEYCUS · Namco converts guide.

Notable games

Tekken 3 (1997), Soul Calibur (1998), Tekken Tag Tournament (1999), Ehrgeiz, Point Blank 2/3, Mr. Driller (1999), Libero Grande, Paca Paca Passion, Um Jammer Lammy NOW!…

Common faults

Symptom Likely cause Lead
Won't boot KEYCUS (CPLD) / flash / ROM board Check KEYCUS; see converts
Corrupt graphics video RAM / ROM board RAM test, contacts
No/partial sound C352 Sound-stage diagnosis
Lost settings RTC/config battery Replace
No image Power, COH board, 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.
  • Flash storage 🟡: data in flash/SIMM — reprogrammable, but a failed block is permanently lost: image it before working on it → PCB preservation hub.
  • Scan rate 📺: PlayStation-based (Sony GPU) → standard ~15 kHz output, a 15 kHz chassis is fine. (Derived from the platform documented above — the screen configuration lives in the GPU device rather than the driver, so it is not measured here.)
  • FPGA / emulation: see the Emulation & FPGA section below.

Repair (technician)

  • KEYCUS (CPLD KCxxx / MACH211 per game): required to boot — check first.
  • PS1 base (COH board): PS1-type faults (recap, GPU/RAM); program in flash.
  • Sound: C352 — diagnose the sound stage.
  • Capacitors: recap. ROM board / contacts: clean.

→ Methods: PCB fault-finding · Recap · EPROM · Traces & vias

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 namcos12
Setting Position Options (default in bold)
Service Mode DIP SW2:1 Off · On
Freeze DIP SW2:2 Off · On

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. There is no measurement table for this platform — MAME's sources yield nothing usable for it. Any frequency quoted under Architecture on this page serves as a marker; otherwise compare against a working board rather than against a number: an invented value condemns healthy parts. → PCB diagnosis

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 (namco/namcos12.cpp).
  • FPGA / MiSTer: no core (a full PS1 base).

Lineage

After the System 11 (1994), before the System 10 (NAND, 2000) and the System 246/256 (PS2).

Photos / assets

(To add: COH board, ROM board, KEYCUS CPLD, program flash.)

What the Tekken 3 kit manual establishes ✅

Read off the Namco America manual archived below, §1 Specifications and §3.1 Precautions.

Item What the manual requires
Power supply 150 W computer-grade · +5 VDC, +5 % / −1 %, 5 A minimum · +12 VDC ±5 %, 2 A minimum
Monitor horizontally mounted · scanning retrace interlace or non-interlace, selectable · horizontal sync 15.75 kHz · vertical sync 60 Hz
Harnesses 56-pin JAMMA plus a second 48-pin harness

⚠️ The +5 V tolerance is asymmetric: +5 % but only −1 %. In other words 5.25 V is allowed, 4.95 V is not. A supply set "roughly to 5 V" that sags under load leaves the range from below before it ever leaves it from above — which tells you which way to turn the pot.

Namco forbids the multimeter on this board

It is written as such in §3.1, and it runs against every troubleshooting reflex:

"The TEKKEN 3 PCB can be damaged by even the small internal voltage of a multimeter. Never attempt to troubleshoot the PCB with such instruments. In the event of a PCB failure please contact your distributor for factory repairs."

— a multimeter's own small internal voltage is enough to damage the board. The manual refers you to the distributor for factory repair, and asks that a returned board be wrapped in anti-static foam or bubble wrap with a note describing the fault and an RMA number.

⚠️ This wiki reproduces the reservation without arbitrating it. It is the manufacturer's, it is categorical, and it contradicts the method this wiki describes elsewhere for JAMMA boards — PCB fault-finding. On a System 12, measuring it means taking a risk Namco explicitly advises against.

Two mounting requirements the manual sets as conditions, not advice: leave clearance for the heat sink's ventilation and for the EMI shield box; and check that the JAMMA harness carries its two ferrite cores, which must end up within a few inches of the EMI box once installation is complete.

Archived original documents ✅

Manufacturer documents archived locally, found on Internet Archive on 13 August 2026 and identified from their title page. ⚠️ The items declare no licence — kept for preservation, provenance named.

Sources & attribution

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.