The Weltronic 811‑3800 Decade‑5 is a three‑channel industrial control unit designed for welding and other high‑power processes, providing precise voltage, current, frequency, and duty‑cycle regulation. Common failure points in this class of equipment include power supply degradation (especially the 230/460 VAC input stage), overheating or burn‑out of MOSFETs and IGBT modules, and failure of the control IC due to electrostatic discharge or overvoltage spikes. Begin troubleshooting by verifying that the unit receives correct line voltage and that all fuses and circuit breakers are intact; then check the output terminals for proper current/voltage levels and inspect the board for burnt components or cracked solder joints; finally review any diagnostic LEDs or error codes displayed on the panel to isolate the fault.[oss-gpt-20b]