Balance commerciale qui pèse mal ? Mise à niveau, calibrage, test des capteurs et règles métrologie légale

An inaccurate retail scale rarely has a dead load cell. Far more often it’s un-level, something is touching the platter, or it simply needs re-zeroing or calibration. And before you reach for tools, one rule overrides everything: if the scale is used to sell goods by weight, it’s legal for trade — you may level and clean it, but calibration must be done by a certified technician. Start here:

Almost every retail scale works the same way: a load cell — a metal element with bonded strain gauges — flexes microscopically under the weight on the platter. That flex changes the gauges’ electrical resistance, producing a tiny signal proportional to the load, which the indicator/terminal amplifies, converts and displays as a weight (and a price).

Because the load cell measures a microscopic flex, the scale is exquisitely sensitive to anything else that pushes on it: an out-of-level stand, a platter touching a wall, vibration, a draft, or moisture in the junction box. That sensitivity is why most accuracy problems are mechanical or environmental — not the cell itself.

The symptom points to the cause. Match yours before assuming the worst:

Work the sequence in order. The first four steps are yours to do; the last is where a legal-for-trade scale hands off to a certified technician.

Calibration corrects the scale’s zero and span against known weights. Who may do it depends entirely on whether the scale is used for trade:

If the scale is level, clean and calibrated but still wrong — especially at heavier loads — the load cell is the prime suspect. Confirm it before replacing:

Browse load cells, indicators and spare parts in our Mettler Toledo scales & spare parts category, and related boards and supplies in POS terminal repair parts. If the fault is a dead indicator or terminal rather than the cell, a power problem may be to blame — see our power supply failure diagnosis guide. Send us your scale model and load-cell rating and we’ll match the right part — and remember a legal-for-trade scale must be recalibrated and re-sealed by a certified technician after the repair.