Interactive Connector Diagram
Click or tap any pin in the diagram below to inspect its signal assignment, electrical specification, and wire colour standard.
Click any pin to view its signal assignment, electrical spec, and wire colour.
Used in Retro Machine Hubs
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Connector Specifications
TI-99/4A Rear AC
Pin 1 = 18V AC, Pin 2 = 8.5V AC, Pin 3 = Common AC Return, Pin 4 = Earth/NC
TI-99/4A DC Molex
Pin 1 = +5.0V DC, Pin 2 = GND, Pin 3 = -5.0V DC, Pin 4 = +12.0V DC
Amiga 2000 (CN400)
14-Pin Header: Pins 1–4=+5V, Pins 5–8=GND, Pin 9=+12V, Pin 10=KEY, Pin 11=-12V, Pin 12=+5V_USER, Pin 13=-5V, Pin 14=TICK
Amiga 4000D (CN405)
6-Pin Inline Molex: Pin 1=+5V, Pin 2=TICK/PWRGOOD, Pin 3=+12V, Pin 4=-12V, Pin 5=GND, Pin 6=+5V
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| TI-99 Rear Pin 1 (Left) | 18V AC Winding | Pwr | TI-99/4A 18–20 V AC (measured to Pin 3 — feeds +12V & -5V stage) | Blue / White |
| TI-99 Rear Pin 2 | 8.5V AC Winding | Pwr | TI-99/4A 8.5–10 V AC @ 1.9 A (measured to Pin 3 — feeds +5V stage) | Brown / Red |
| TI-99 Rear Pin 3 | AC COMMON | GND | TI-99/4A Common Return for both AC windings (Pin 4 = Earth/NC) | Black |
| TI-99 Internal 1–4 | +5V / GND / -5V / +12V | Pwr | TI-99/4A Internal 4-Pin Harness: 1=+5V, 2=GND, 3=-5V, 4=+12V | 4-Wire Molex |
| A2000 CN400 Pins 1–4 | +5.0V DC | Pwr | Amiga 2000 Main +5 V Logic Rail | Red |
| A2000 CN400 Pins 5–8 | GND (0 V) | GND | Amiga 2000 Digital Ground Return | Black |
| A2000 CN400 Pin 9 & 11 | +12V (9) & -12V (11) | Pwr | Amiga 2000 +12 V DC (Pin 9) & -12 V DC (Pin 11; Pin 13 = -5V) | Yellow / Blue |
| A2000 CN400 Pin 14 | TICK (50/60 Hz) | In | Amiga 2000 50/60 Hz Square-Wave CIA Clock (or move J300 to VSYNC!) | Grey / Purple |
Handling the 50/60Hz TICK Signal on Big-Box Amiga ATX Conversions
The TI-99/4A uses a 4-pin rear receptacle carrying two AC transformer windings (18 V AC and 8.5 V AC) into an internal slide-in regulator board that generates +5 V, -5 V, and +12 V. Big-Box Amigas (A2000, A3000, A4000D) use internal multi-pin Molex motherboard power headers carrying +5 V, +12 V, -12 V, -5 V, and a 50/60 Hz mains-derived TICK clock.
- Amiga 2000 ATX Adapter: Move motherboard jumper J300 from Pins 1–2 (PSU TICK) to Pins 2–3 (VSYNC) so Agnus provides the 50/60 Hz TOD clock to CIA-A!
- Amiga 3000 & A4000D ATX Adapter: Ensure your ATX-to-A3000/A4000 adapter cable includes an onboard 555/crystal 50 Hz TICK oscillator (or ties PWRGOOD/TICK appropriately).