Buying used test instruments: a practical inspection checklist

Used instruments can be suitable for development, troubleshooting and backup stock, but a sound purchase starts with the actual test requirement and the offered unit's condition.

Record bandwidth, measurement range, resolution, channels, interfaces, accuracy, electrical safety category and required installed options. Check the manufacturer's manual. Optional modules and software licences vary between instruments with an identical base model.

A power-on check, a limited functional check and a traceable calibration certificate answer different questions. A readable display does not prove that an instrument meets a specified accuracy requirement. Where a regulated or quality-controlled process requires traceability, request the issuing laboratory, calibration date, scope, uncertainties and validity of the supplied certificate; do not infer its existence from the word tested.

Verify probes, leads, connectors, fixtures, adapters, batteries and software against the individual seller's included-item description. Manufacturer brochures often show accessories that are not included in second-hand stock. Check licence transfer rules independently.

Inspect actual photographs for damaged sockets, corrosion, cracked displays, missing buttons and evidence of previous repair. Read the condition statement and applicable returns and warranty terms. If safety or calibration is critical, have a competent engineer inspect the item before use.

Browse Combay test and measurement stock or request photographs and technical clarification.