The Lab‑A‑Tron DX‑116DC is a digital current‑loop transmitter that converts a process signal into a 4–20 mA output for industrial control systems. Common failure points include the input conditioning circuitry (op‑amp bias drift, capacitor leakage), the analog‑to‑digital converter (bit‑shift errors or stuck bits), and the power supply rails (decoupling capacitor failure or voltage regulator dropout). Typical symptoms are erratic output, zero‑output at all inputs, or a constant 20 mA regardless of input. First‑check diagnostics: verify that the unit’s supply voltage is within spec and stable; inspect the I/O loop for proper wiring and continuity; visually examine the board for cracked solder joints or burnt components; then read any diagnostic LEDs or error codes if available.[oss-gpt-20b]