Nikki Denso 03269 is a 12 V DC servo controller used in industrial motion‑control systems. The most common cause of the “12 V DC dropping out while running” symptom is intermittent loss of supply to the power‑regulation circuitry—often due to a failing voltage regulator, overloaded or shorted filtering capacitor, or a degraded main power fuse/connector. Secondary possibilities include a high‑current draw spike from an overloaded motor driver or a fault in the input power conditioning board that trips under load.

First‑check diagnostics: verify the 12 V rail at the controller’s input with a multimeter while the unit is running; inspect for voltage sag and confirm the fuse rating matches current demand. Inspect the regulator ICs, bypass capacitors, and heat‑sink for signs of overheating or cracking. Finally, check all power connectors and wiring harnesses for loose contacts or corrosion that could cause intermittent loss under load.[oss-gpt-20b]