The NeXTstation Color uses a proprietary Y-cable to split the back-of-CPU 13W3 connector into two paths: analog RGB video to a monitor, and DB19 keyboard/mouse signals to the SoundBox. Original cables are increasingly hard to find on the secondary market, so when I needed one I built it from scratch and drew up the wiring myself.
The diagram covers all three connector ends:
- 13W3 (NeXT CPU side, male) — the three coax-style pins A1, A2, and A3 carry RED, GREEN, and BLUE. The smaller pins around them carry the SoundBox signals: ADB, GND1 and GND2, the power-switch line, VMODEINJ, ±12V, CLOCK, and the two keyboard-data directions.
- DB19 (SoundBox side, male) — 19-pin connector that receives those SoundBox signals from the 13W3 end of the cable.
- VGA 15-pin (Monitor side, male) — standard VGA pinout: pins 1, 2, 3 carry RED, GREEN, BLUE; pins 6, 7, 8 carry the matching grounds.
A few notes from building it:
- Wire and verify the video side first. Sync-on-green is in effect on the NeXT, so you only have one shot at getting the analog RGB right before troubleshooting gets harder.
- Once video syncs cleanly, the DB19 side is tedious but mechanical — point-to-point soldering against the diagram, one signal at a time.
- DB19 connectors are notoriously hard to find. Plan for that part of the build separately; sometimes 3D-printed shells with hand-installed pins are the only option.
For an alternative reference, see also Asterontech’s NeXT VGA Y-cable build notes.