The Tecnologic THP48 is a 110 V AC digital temperature controller (model THP48‑FCCR) used for process or heating applications; it has been discontinued and replaced by the K48‑HCR series. Common failure points in this class of units include power supply degradation, relay contact wear, LCD/indicator panel failure, and loss of communication with external I/O modules due to broken traces or connector corrosion. First‑check diagnostics: verify 110 V input and proper grounding; inspect the main power board for burnt components or loose connections; review any error codes displayed on the front panel or via serial/debug interface; finally test the relay contacts and indicator LEDs for continuity and correct operation.[oss-gpt-20b]