Guardimark Light Curtains 703516 controller is an industrial safety control module that processes optical array signals and triggers emergency stops or interlocks. Common failures on this model include power‑supply dropout, burnt or tripped MOSFETs in the LED driver board, and degradation of the internal microcontroller due to over‑voltage or thermal cycling; these often manifest as intermittent shutdowns or no response to sensor input. First‑check diagnostics: verify 24 V DC supply voltage and continuity to the LED array; inspect the main PCB for burn marks or cracked components and test I/O pins against expected logic levels; review any diagnostic LEDs or error codes displayed on the unit’s front panel.[oss-gpt-20b]