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Capcom ZN-1 / ZN-2

Capcom arcade platform (1995/1997), based on the Sony ZN hardware (PlayStation architecture), shared with Tecmo, Taito, Psikyo… A ZN motherboard + a publisher-specific B-board. Star Gladiator, Rival Schools, Street Fighter EX…

The Sony CXD8530CQ CPU on a ZN board — it is the PlayStation's processor, and it sums the architecture up.
The Sony CXD8530CQ CPU on a ZN board — it is the PlayStation's processor, and it sums the architecture up. Photo: Baz1521, CC BY-SA 3.0, via Wikimedia Commons.

Identification

Field Value
Manufacturer Capcom (Sony ZN hardware)
Years ZN-1 (1995) · ZN-2 (1997)
Base PlayStation (arcade)
Structure ZN motherboard + publisher B-board
Media ROMs (B-board)

Architecture (≈ PS1)

Block Chip Clock Role
CPU MIPS R3000A ~33.9 MHz + GTE/MDEC (like the PS1)
GPU Sony custom (PS1)
Sound QSound (Capcom ZN boards); other manufacturers = in-house chips
Media B-board ROM (Capcom) / boards per publisher ZN-1 then ZN-2 (faster)

ZN = a PS1-based Sony arcade platform, licensed to Capcom (CPS Changer → "ZN"), Tecmo, Taito, Psikyo, Eighting… — hence physically different boards per publisher, but a common PS1 base.

ZN-1 vs ZN-2: the ZN-2 (1997) is a faster revision (optimised bus/memory) for later games, but still an arcade PS1 base.

Notable games

  • Capcom: Star Gladiator, Rival Schools, Street Fighter EX / EX2, Plasma Sword, Tech Romancer.
  • Other publishers (same ZN base): Bloody Roar (Hudson/Eighting), Beastorizer, Brave Blade / Shanghai (Raizing/Eighting), Tecmo golf, Sonic Wings Limited (Psikyo), Taito FX-1…

Security & preservation

Some B-boards have a protection / battery → suicide vigilance on those titles. The security relies on the CAT702 chip (common to the Sony ZN family). See also the kinship with the PlayStation.

→ Same ZN base & CAT702 chip on the Taito side: Taito G-NET (mod-BIOS, CF cards)

Faults & preservation

  • Contacts motherboard ↔ B-board.
  • Targeted recap.
  • Protection battery depending on the game.
  • Emulation: MAME (zn.cpp); the CAT702 crack (2009) opened up the security understanding (see G-NET). PS1 emulators don't apply (distinct arcade hardware). No FPGA/MiSTer core (a full PS1 base).

EPROM repair

PlayStation base (R3000). Program/data on a ROM board (mask ROM + EPROM) per game; CAT702 security. Conversion/de-protection: ZN converts (via Taito G-NET).

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 🟡: 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 📺: 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)

  • CAT702 protection (ZN security ASIC) + a battery on some B-boards: watch for suicide — a dead board can be a flat key/battery, not a fault. See backup batteries.
  • PS1 base (R3000A + Sony GPU): the same fault families as a PS1 (recap, GPU/RAM).
  • Sound: QSound (Capcom boards) — diagnose the sound stage.
  • Capacitors: recap PSU + audio filtering. Oxidised EPROM sockets: turned-pin socket.

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

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. On this platform the battery is the first suspect: its leakage eats tracks under the holder, and the damage is often hidden by the battery itself. Lift it to look.

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.

Procedure — replacing the battery without losing the key ✅

Not every board in this family is concerned

Check on this page whether your game is one of the encrypted ones before touching anything. On the others the battery only holds settings, and losing it costs nothing but a re-setup.

The order is the whole procedure

The decryption key of the CAT702 lives in SRAM held up by that battery. Cutting the old cell before the new one is soldered erases it, instantly and for good: the board goes silent and only a de-suicide brings the game back. So the new cell goes in first, in parallel.

  1. Board powered off, old battery left in place.
  2. Measure the old cell in circuit and note it (a CR2032 is 3 V nominal). This is what tells you whether you are ahead of the failure or already behind it.
  3. Solder the new cell in parallel with the old one — piggyback — watching polarity. A reversed cell discharges the old one through itself and erases the key just as surely.
  4. Re-measure at the holder: the voltage must have come back up. Do not go on before it has.
  5. Only now, remove the old cell.
  6. Power up and check the game boots.

→ Backup batteries

Already dead? This procedure will not bring it back — the key is gone.

Photos / assets

(To add: ZN motherboard, B-board, battery.)

Sources & attribution

Image:

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.

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