BIAONU LED Driver Board for ELEGOO Mars 4 Ultra

The constant-current board that drives the Mars 4 Ultra's UV module. Its failure looks exactly like a dead light engine: the printer runs the whole job, the vat stays clear, and the light under the LCD either never comes on or quits after a handful of layers. Check this board before buying an expensive emitter. BIAONU builds it — ELEGOO lists no equivalent spare.

Specifications

• 24 V input, 18–20 V output, 0.6–4.0 A
• Constant-current regulation for the COB light module
• Current trimmer and a heatsinked switching transistor
• LED+ / LED− terminals and a 24 V input with marked polarity

Compatibility: ELEGOO Mars 4 Ultra. The seller doesn't claim the plain Mars 4 or the Mars 4 Max, so don't order it for those without asking first. Once installed, set the current with the trimmer to suit your emitter and run a test print to check the bottom layers — the factory setting doesn't always match stock.