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
TRS-80 Model I (J4)
5-Pin 180° DIN (Pins 1 & 3 = 14–16V AC; Pin 2 = GND; Pin 4 = +19–22V DC Unreg)
Dragon 32 / 64
5-Pin 240° DIN (Pins 1 & 2 = 8.5V AC; Pin 4 = 0V CT; Pins 3 & 5 = 14V-0-14V AC)
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| Model I Pin 1 | 14–16V AC (Leg 1) | Pwr | TRS-80 Model I AC Winding Leg 1 (feeds internal +5V & -5V rectifiers) | Yellow |
| Model I Pin 2 | GND (0 V DC) | GND | TRS-80 Model I DC Return Ground (for Pin 4 +19V DC) | Black |
| Model I Pin 3 | 14–16V AC (Leg 2) | Pwr | TRS-80 Model I AC Winding Leg 2 | Yellow |
| Model I Pin 4 | +19–22V DC Unreg | Pwr | TRS-80 Model I Filtered DC (feeds internal LM723 +12V regulator for 4116) | Red |
| Model I Pin 5 | NC | NC | Unconnected on Model I Power DIN | NC |
| Dragon Pin 1 & 2 | 8.5V AC (1.5A) | Pwr | Dragon 32/64 Main 8.5 V AC Winding (feeds internal +5V regulator) | Blue |
| Dragon Pin 3 & 5 | 14V AC (28V CT) | Pwr | Dragon 32/64 28 V Center-Tapped AC Winding (feeds +12V & -5V rails) | Red / White |
| Dragon Pin 4 | 0V Center Tap | GND | Dragon 32/64 Center Tap Ground for 28V AC winding | Black |
Verifying 4116 Triple-Rail Sequencing on Model I & Early Dragon 32
Both the TRS-80 Model I and the Dragon 32/64 house their voltage regulators (7805, 7812, 7905, LM723) on the computer motherboard and use an external multi-winding transformer brick connected via a 5-pin DIN plug.
- Before fitting eight 4116 DRAMs into a TRS-80 Model I (Z13–Z20) or early 16-socket Dragon 32, power on with the RAM sockets empty and verify Pin 1 = -5.0 V DC, Pin 8 = +12.0 V DC, and Pin 9 = +5.0 V DC on the DRAM sockets!