The Pneumercator LDE‑700 900369 is a liquid‑level monitoring controller that supplies audible, visible and optional printed alarms for high/low level conditions, two switch‑input alarms, and two precision leak detection inputs. Common failure modes include loss‑detection or alarm output faults, leakage sensor misreadings, power supply dropout (120 VAC ±10 % with 48 W consumption), MOV surge protection tripping, and undervoltage shutdowns. First‑check diagnostics: verify the 120 VAC input voltage and continuity to the board; inspect all alarm output terminals for proper polarity and resistance; examine leak sensor wiring and test the two leak inputs with a multimeter or oscilloscope for signal integrity.[oss-gpt-20b]