5 PIN Commodore C128 Power Connector
| Pin | Name | Description | Current [A] |
|---|---|---|---|
| 1 | +5VDC | +5 Volts DC | 2.5 |
| 2 | GND | Ground | |
| 3 | 9VAC | 9 Volts AC | 1.0 |
| 4 | GND | Ground | |
| 5 | 9VAC | 9 Volts AC | 1.0 |
The Commodore 128, released in 1985, uses a 5-pin square DIN connector for its external power supply. Unlike the Commodore 64’s 7-pin round DIN brick, the C128 PSU is a switching-type unit rated at 5 VDC and 9 VAC, making it more electrically robust. The 9 VAC output is used internally by the Z-80 clock circuit and for generating additional regulated voltages. The connector’s square metal shell also serves as a chassis ground reference, as documented in the official Commodore 128/128D Service Manual (PN-314001-08, November 1987).
Notes
- AC lines are in opposite phases
- The connector is a 5-pin square DIN; the metal shell of the connector also serves as a ground connection.
- The C128 PSU is a switcher type (part number C 326189-01), rated 5 VDC at 4.3 A and 9 VAC at 1 A. The 9 VAC supply is required for the Z-80 clock circuit to function.
- WARNING: The 5-pin square DIN connector is physically identical to the power connector used on the Amiga 500, 600, and 1200, but the voltage assignments are entirely different. Connecting an Amiga PSU to a C128, or a C128 PSU to an Amiga, will destroy the computer.
- Pin 2 is listed as GND in some references; Ray Carlsen’s repair documentation lists pin 2 as NO CONNECTION, with the shell providing the chassis ground path. Do not rely on pin 2 for ground in repair work.
Signals
- +5VDC — Regulated 5 volt DC supply from the switching PSU; rated 4.3 A total from the PSU unit.
- GND — Ground reference; the connector’s square metal shell also carries chassis ground.
- 9VAC — 9 volt AC supply (unregulated); used internally for the Z-80 clock circuit and secondary voltage generation. Carried on both pins 3 and 5 in opposite phases.