The Bycan RB‑142825 is a dual‑output auxiliary power unit and battery charger that supplies either 14 V or 28 V DC at up to 25 A, with built‑in circuit protection and an AC input of 220 V. Common failure points for this class include tripped or blown internal fuses, degraded rectifier diodes in the DC output stage, worn thermal overload relays, and aging power supply capacitors that can cause voltage sag or overheating. Initial diagnostics should verify the 220‑V AC supply continuity, check the status of all fuses and circuit breakers, and perform a visual inspection for signs of burn marks or corrosion on the DC output terminals. Next, measure the DC output under no load to confirm correct voltage levels and inspect the rectifier bridge with an ohmmeter for open circuits; finally review any error codes displayed on the unit’s panel or log if available.[oss-gpt-20b]