How a coin validator works in a vending machine and why it sometimes rejects valid coins.
A coin validator measures features of the inserted coin, such as diameter, thickness, and metal properties, and compares them with stored patterns. If the coin does not match, it is returned.
Measurement
The coin passes sensors that check its dimensions and electromagnetic properties.
Decision
The controller compares the result with stored patterns. Recognized coins go to the cash box or change dispenser; others are returned.
Why a Coin Comes Back
A worn or dirty coin may not match the stored pattern. Try again or use a different coin.
FAQ
Does a validator accept foreign coins? Only those it is programmed to accept.
Can a validator be calibrated? Yes, a technician does it following the manufacturer's instructions.