Troubleshooting Techniques & Repair Methods Flashcards
7 cards from real CST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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A digital scale displays a stable reading but consistently shows values 2% above the certified value across its entire range. What is the most likely cause?
Answer: Incorrect span calibration
A consistent percentage error across the entire range indicates an incorrect span calibration rather than a hardware fault.
When troubleshooting a scale that returns to zero correctly but gives erratic readings under load, what should be checked first?
Answer: Mechanical binding or restriction of the platform
Erratic readings under load that disappear at zero typically indicate a mechanical issue such as binding, side loading, or debris under the platform.
A technician measures the mV/V output of a load cell and finds it is within specification, but the indicator still reads incorrectly. What is the next logical diagnostic step?
Answer: Check the indicator's internal calibration and input range settings
If the load cell signal is correct, the fault lies in the indicator's processing — checking its calibration and input range settings is the next step.
A load cell's insulation resistance between the cable shield and signal wires measures 50 MΩ when it should exceed 1000 MΩ. What condition does this indicate?
Answer: Moisture intrusion or cable damage
Low insulation resistance between shield and signal wires indicates moisture intrusion or cable damage, which can cause unstable or drifting readings.
A vehicle scale gives a correct reading for the first axle but a significantly different total when both axles are on. Which component is most suspect?
Answer: One or more load cells contributing to only part of the platform
When a partial-platform reading is correct but the full-platform reading is not, a load cell covering the unloaded section is likely faulty or disconnected.
During a zero-return test, a scale repeatedly drifts positive by 0.5 divisions after each weighing cycle. What is the most probable cause?
Answer: Material buildup under the platform
Progressive positive zero drift after each cycle indicates material accumulating under the platform and adding tare load.
A technician replaces a load cell in a multi-cell floor scale. After replacement, the summed output is correct at full capacity but the cornerload test fails. What must be performed?
Answer: Perform a cornerload or section adjustment
After replacing a single load cell, a cornerload or section adjustment must be performed to rebalance the contributions of each cell to the total output.