Where Your Wires Go

ST-DC4 v2.2.1 · 4CH RELAY · HJH5 CABLE · L&P 50 II // KAREN'S BED
YELLOW — Head Up (HU)
WHITE — Common (GND)
BLUE — Head Down (HD)
RED — VDD Power (DO NOT CONNECT)
Board Terminal Layout — Looking at the bottom of your ST-DC4
ST-DC4 v2.2.1 RELAY BOARD — TERMINAL SIDE (BOTTOM) RELAY 1 CH1 RELAY 2 CH2 RELAY 3 UNUSED RELAY 4 UNUSED NO1 COM1 NC1 NO2 COM2 NC2 NO3 COM3 NC3 NO4 COM4 NC4 USB 5V YELLOW Head Up WHITE Common (2 branches) BLUE Head Down RED PASS THRU NO CONNECTION ⚠ UNUSED Future LEDs
Screw Terminal Cheat Sheet
Terminal Wire From Cable Action
NO1 YELLOW HU pad on remote PCB Head Up signal
COM1 WHITE (branch 1) GND pad on remote PCB Common return
NO2 BLUE HD pad on remote PCB Head Down signal
COM2 WHITE (branch 2) Same wire as COM1 Common return
RED RED VDD — power wire ⚠ PASS THROUGH ONLY
NO3/NO4 — Empty Future use
Build Order
01
Splice White
Cut White, rejoin straight through + add 2 pigtail branches at the junction. One branch goes to COM1, other to COM2. Solder + heat shrink.
02
Splice Yellow
Cut Yellow, rejoin straight through + add 1 pigtail branch. Branch goes to NO1. Solder + heat shrink.
03
Splice Blue
Cut Blue, rejoin straight through + add 1 pigtail branch. Branch goes to NO2. Solder + heat shrink.
04
Red = Hands Off
Cut Red, rejoin straight through only. No branch. No relay connection. Just passes through untouched.