First, check whether the sensor of the asphalt scale senses correctly (whether the asphalt scale is completely suspended). Check the electronic analog metering module after the mechanical failure is eliminated. As upstairs said, while adding weights, use a multimeter to check whether the changes of voltage and resistance are normal. Also check the voltage amplifier of the metering module. If there is something wrong with the amplifier, there will be a metering boost error.

It seems that the problem added by the landlord is obviously that there is a problem with the asphalt metering amplifier, but it is not necessarily damaged. Maybe someone just accidentally moved it and could adjust it back. If this happens sometimes, it is broken and must be replaced. For example, the actual weighing is: 10KG/20KG/30KG, while the display weighing is: 6.5kg/13kg/19.5kg. This is the amplifier problem.