Laboratory Instrument Repair: Experience and Principles

1. Reproduce the fault yourself where possible. Do not rely solely on accounts from users or third parties; observe carefully, especially when information is secondhand. Some operators may say the instrument failed suddenly without intervention to avoid responsibility. Engineers should handle such situations tactfully.

　　2. Check external causes before internal ones. Do not open the housing before making a preliminary diagnosis and ruling out likely causes. Hoping to spot a broken wire or obvious fault is guesswork. Approximately 50% of faults arise from the environment, operation or cleaning. Consider prolonged shutdown, large day-night temperature changes, proximity to elevators, nearby equipment and computer settings.

　　3. Check power before the main unit, and accessories before the main unit. Confirm stable power, acceptable loading, proper earthing, functioning electrodes and accessories, and correct connections.

　　4. Use panel buttons, displays, operating procedures and service procedures to isolate faults. This important step requires detailed knowledge of the instrument's structure.

　　5. Understanding users' habits, staffing and skill levels, and the department's finances can aid maintenance. These factors may indicate cleaning quality or a wish to replace the instrument, in which case repairs may never be considered satisfactory.

　　6. Do not casually replace original instrument components, boards or tubing, because some parts are linked to circuit boards or software data. Repeatedly swapping boards and components to narrow down a fault is not a substitute for skilled diagnosis, although this approach is common.

　　7. Sometimes the instrument or engineer may have to accept blame. Assigning responsibility to the department or user can complicate future cooperation. Faults may also occasionally be introduced deliberately for various reasons.