Step 10.27 — Leviathan HEATBED → SSR INPUT¶
Step 27 of 80 · Chapter 10 — Wiring and Checkpoint #1
Parts:
- SSR to MB cable ×1 · the Cable Kit box
Do: SSR SIG end onto the SSR's INPUT 3&4: red to INPUT 3, black to INPUT 4. To SSR end onto the Leviathan's HEATBED terminals.
Check
Red on 3, black on 4, and red on the Leviathan HEATBED +. Trace the pair from board to relay with a finger.
What you're looking at
HEATBED on the Leviathan is a low-current DC output; it never carries bed power, it only tells the relay when to conduct. This polarised red/black pair is the entire control link between the firmware and a mains heater.
Caution
Rev D+ / LDO: reversed INPUT 3/4 means the SSR never fires and the bed stays cold. The dangerous failure is the other one — a shorted relay, which leaves the bed permanently live with no thermal control; that is what 10.21 and 10.78 test for. src
Source: LDO Rev D photo S4 24 V/SSR mapping · LDO wiring guide § Connecting 24V
