Sega Astro City¶
Sega's emblematic candy cab (1993): a compact seated cabinet, 29" screen, interchangeable control panel, JAMMA standard. A pillar of the "City" series and a reference for Japanese fighting/shmup play.
Identification¶
| Field | Value |
|---|---|
| Manufacturer | Sega |
| Year | 1993 |
| Type | Candy cab (compact seated cabinet) |
| Screen | CRT 29", Nanao MS8 (sometimes MS9), 15/24 kHz, rotatable (tate/yoko) |
| Controls | 2 players, interchangeable panel (typical config: 8-way stick + 6 buttons/player) |
| Power | 100 V (Japan), ~140 W |
| Accepted PCB format | JAMMA |
| Dimensions | 905 × 750 × 1445 mm (W×D×H) |
| Weight | 93 kg |
⚡ Connector & power¶
| Aspect | Value |
|---|---|
| PCB connector | JAMMA (56-pin edge) — no JVS (a 1993 cabinet) |
| Monitor sync | 15/24 kHz (Nanao MS8/MS9), no native 31 kHz |
| Power | 100 V AC (Japan) |
| Consumption | ~140 W |
| Dimensions | 905 × 750 × 1445 mm (W×D×H) |
| Weight | ~93 kg |
(Sources: Arcade Otaku; consumption/dimensions from the service manual.)
→ Detailed wiring: a JAMMA cabinet → see JAMMA wiring (56-pin pinout) and Control panels & buttons (Sega layout, interchangeable panel).
Anatomy¶
- Marquee (lit header) at the top.
- 29" CRT monitor on a rotatable frame (horizontal and vertical games).
- Interchangeable control panel (unscrews, harness to the board).
- Coin mech + service door.
- Sega PSU + JAMMA harness (+ kick harness per game).
- PCB tray (approx. 48 × 40 cm).
The "City" series¶
Sega's candy cab lineage: Aero City (predecessor) → Astro City (1993) → New Astro City (1995, Nanao MS9 monitor, improved speakers) → Blast City, Net City, Versus City (two back-to-back)… then the Naomi cabs.
Wiring¶
JAMMA connector (edge)¶
The cabinet is standard JAMMA (56 pins, finger-to-finger). Reference pinout (source: Arcade Otaku):
| Pin (solder / component) | Solder side | Component side |
|---|---|---|
| A / 1 | Ground (GND) | Ground (GND) |
| B / 2 | Ground (GND) | Ground (GND) |
| C / 3 | +5 V | +5 V |
| D / 4 | +5 V | +5 V |
| E / 5 | −5 V | −5 V |
| F / 6 | +12 V | +12 V |
| H / 7 | Key (notch) | Key (notch) |
| J / 8 | Counter 2 | Counter 1 |
| K / 9 | Lockout 2 | Lockout 1 |
| L / 10 | Speaker − | Speaker + |
| M / 11 | Audio ground | Audio + |
| N / 12 | Video Green | Video Red |
| P / 13 | Video Sync | Video Blue |
| R / 14 | Service | Video ground |
| S / 15 | Tilt | Test |
| T / 16 | Coin 2 | Coin 1 |
| U / 17 | Start 2 | Start 1 |
| V / 18 | P2 Up | P1 Up |
| W / 19 | P2 Down | P1 Down |
| X / 20 | P2 Left | P1 Left |
| Y / 21 | P2 Right | P1 Right |
| Z / 22 | P2 Button 1 | P1 Button 1 |
| a / 23 | P2 Button 2 | P1 Button 2 |
| b / 24 | P2 Button 3 | P1 Button 3 |
| c / 25 | (P2 Button 4) | (P1 Button 4) |
| d / 26 | (P2 Button 5) | (P1 Button 5) |
| e / 27 | Ground (GND) | Ground (GND) |
| f / 28 | Ground (GND) | Ground (GND) |
Buttons 4-6 & the key
Buttons 4, 5, 6 (fighting games) generally go through a separate kick harness, not standard JAMMA (pins 25/26 in parentheses = not universal). Respect the key (pin 7): a reversed connection can fry the board.
Internal harness (cab side)¶
Connectors of the Astro City's internal harness (source: Arcade Otaku, Wiring Guide). The control panel handles 5 buttons + start per player.
Player 1 / Player 2 — 12 pins (same pinout for both):
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1 | Start | 7 | Button 2 (SW2) |
| 2 | Right | 8 | Button 3 (SW3) |
| 3 | Left | 9 | Button 4 (SW4) |
| 4 | Up | 10 | Button 5 (SW5) |
| 5 | Down | 11 | +5 V |
| 6 | Button 1 (SW1) | 12 | GND |
Audio — 4 pins, stereo:
| Pin | Function |
|---|---|
| 1 | Left + |
| 2 | Left − |
| 3 | Right + |
| 4 | Right − |
Kick harness (buttons 4/5/6, fighting games) — a separate AMP UP 10-pin harness:
Auxiliary: 10 pins (AUX 1 → 10). Earth: pin 1 = Earth, pin 2 = N/C.
Monitor connector (video + AC)¶
The monitor runs through a single 15-pin AMP connector (the one you unplug during disassembly): it carries the RGBS video signal (pins 1-5), the monitor AC (6-7) and the degauss (9-10):
Stereo sound¶
The Astro City can output stereo sound — notably better on games that support it (Konami shmups, CPS-2…). (Procedure after Arcade Otaku.)
Needed: a stereo amp (often already in the cab, otherwise cheap), a stereo game, and a loom for the amp input (the JVS conversion loom exposes RCA — handy for CPS-2, Gradius IV).
- Unplug the mono harness from the speakers: locate the two yellow AMP-Universal Power connectors at the bottom of the cab (the female has a loop between pins 2-3, red + blue wires). Unplug; let the female hang at the bottom. Don't cut it (useful for a future mono game).
- Plug the male into the PSU's yellow "Sound Out" connector → speakers connected to the amp.
- Volume to zero (otherwise you risk frying the speakers).
- Connect a loom to the amp's "Sound In" (red) input. A JVS loom for RCA / 3.5 mm jack outputs (CPS-2, Gradius IV). For a 4-pin JST (old Konami): pins 1-2 = left, 3-4 = right — check the game's manual.
- Connect the game (amp + JAMMA), volume to zero, power on, raise slowly (via the sound test if available).
Disassembly¶
(After thomj's "Strip Down Guide" / Arcade Otaku; applies to Astro City, Astro City II and New Astro City.)
- Remove the panel behind the fluorescent tube (Phillips screws; sometimes security Torx originally).
- At the front: open the control panel, remove the screws of the monitor bezel.
- Unplug the AMP connector feeding the bezel speakers.
- Remove the monitor bezel.
- Unplug the monitor: remove the 15-pin AMP connector; handle the remote board (unplug the ribbon, or unscrew the remote board in the CP).
- Remove the bolts holding the monitor to the chassis, take out the monitor.
- Separate the two halves of the base: screws at the rear bottom + on the sides (very stubborn).
JIS screws (classic trap)
The base screws are JIS (Japanese Industrial Standard), different from Phillips/Pozidriv — a Phillips screwdriver damages the head. Use a JIS bit + ratchet for torque. The most seized ones may need a screw extractor or grinding the head with a Dremel.
Internal boards¶
The main electronic sub-assemblies ("boards") — dedicated pages to create:
- 🖥️ Monitor: Nanao MS8 CRT chassis (sometimes MS9), 29", 15/24 kHz. → Repair: Nanao MS8 · Nanao MS9
- ⚡ Power block (Sega PSU) → Sega PSU repair.
- 🔗 Harness / distribution: JAMMA + kick harness + power + monitor.
Monitor adjustments (CRT)¶
- Geometry / convergence / purity via the chassis adjustments (mind the HV).
- Recap the monitor chassis if the image shakes / colours bleed.
- Degauss in case of colour patches.
High voltage
A CRT stores high voltage even when off. Discharge the tube before any work; don't work alone if untrained.
Common faults¶
| Symptom | Likely cause | Lead |
|---|---|---|
| Shaky image / bleeding colours | Monitor chassis capacitors | Recap the chassis |
| Colour patches on screen | Magnetised shadow mask | Degauss |
| No image but sound OK | Chassis / HV / monitor connectors | Chassis diagnosis |
| Game won't start | JAMMA harness / power / board contacts | Check power, reseat the board |
| Flaky buttons/stick | Worn microswitches, CP harness | Replace switches |
Maintenance & restoration¶
- Clean the plastic body ("curvy body"), marquee plexi and bezel.
- Refurbish the control panel (stickers, buttons, stick — often Sanwa/Seimitsu).
- Check the JAMMA harness, clean the contacts.
Common mods¶
- Native RGB: candy cabs already output clean RGB to the monitor.
- Supergun-friendly: connect isolated PCBs easily (JAMMA).
- LCD screen: LCD conversions exist (loses the CRT look).
- 31 kHz / tri-sync: the MS8/MS9 is 15/24 kHz; for 31 kHz (Naomi/VGA) you need a tri-sync monitor/chassis swap.
- → Modernising a cabinet: OSSC/GBS-Control, a Mean Well PSU, JVS conversion, I-PAC/J-PAC encoders, PC/FPGA in the cab.
Manuals & schematics (archived)¶
Locally archived copies (protection against dead links):
- 📘 Service manual — PDF
- 🔄 Monitor rotation (tate/yoko) — PDF
- 🏷️ Decals — Instruction Space · Warning
Photos / assets¶
(To add: full cabinet, rotatable monitor, control panel, JAMMA harness.)
Repair & maintenance
CRT monitor (discharge HV!) → CRT safety + Nanao MS8 / MS9 chassis · Sega candy PSU → PSU repair · recap → Recap.
Sources & attribution¶
Text (content synthesised/transcribed here, sources cited for attribution):
- Arcade Otaku Wiki — Sega Astro City (specs) — https://wiki.arcadeotaku.com/w/Sega_Astro_City
- Arcade Otaku Wiki — JAMMA (pinout) — https://wiki.arcadeotaku.com/w/JAMMA
- Arcade Otaku Wiki — Sega Astro City Wiring Guide (internal harness) — https://wiki.arcadeotaku.com/w/Sega_Astro_City_Wiring_Guide
- Arcade Otaku Wiki — Astro City Stereo Wiring — https://wiki.arcadeotaku.com/w/Astro_City_Stereo_Wiring
- NFG Games / GameSX — Sega City cabinet pinouts (AMP Universal MATE-N-LOK connector families, 12-pin matrix CP, 10-pin kick) — https://gamesx.com/wiki/doku.php?id=arcade:sega_city_cabinet_pinouts
- New Astro City Strip Down Guide by thomj (Arcade Otaku) — disassembly — https://wiki.arcadeotaku.com/w/New_Astro_City_Strip_Down_Guide
- Hard-Candy.com — Astro City — to reference — https://www.hard--candy.com/wiki/candy/Astro_City
Image:
-
astro-city.jpg— "The real dog god" (Wikimedia Commons), public domain — https://commons.wikimedia.org/wiki/File:Sega_astro_city_candy_cab.jpg
Review & corrections
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