BIAONU UV LED Board for ELEGOO Mars 4 & Mars 4 Max

A replacement UV light engine for the Mars 4 LCD. The usual symptom before a swap: prints still come off the plate but they're brittle and translucent, and anything near the edge of the build area barely cures at all — the emitter has lost output. BIAONU makes this board; it's an aftermarket part, since ELEGOO doesn't sell light engines through its own store.

Specifications

• 36-die COB emitter, 405 nm wavelength
• 88 W rated output
• Metal-core PCB with four mounting holes
• Power leads pre-soldered, polarity silkscreened on the board

Compatibility: ELEGOO Mars 4 (7" 9K panel) and Mars 4 Max (9.1" 6K). The two panels are different sizes, so the exposure areas differ too — the seller ships both versions from one listing, which means you have to pick the variant for your printer instead of accepting the default. The Mars 4 Ultra and Mars 3 use their own boards.