There are many possible problems which can be encountered with change machines. Change machine power voltage levels vary based on the type of machine you own. If the levels are not sufficient to power the machine, it will not operate reliably, if at all. A more common problem is when banknotes get jammed. There are many reasons why this could happen; the banknote could be crumpled up or torn or the banknote acceptor could be damaged. Addressing either one of these issues is possible by following a few short steps.
Verify that the power supply plug is on. Use the multimeter and check the voltage level on the power supply. Contact the manufacturer for a power supply replacement if the levels are not within the recommendations listed in your user's manual.
Check the banknote acceptor. Remove jumbled coins, fill up the coin hopper if one or more hoppers are low on coins. Contact the manufacturer for a banknote acceptor replacement if that part is damaged.
Review the instructions for proper banknote jam removal. For example, some jam removal steps require the operator to open the cover, turn off the machine, disconnect the cable to the banknote acceptor (in that order). The handle levers must be squeezed together so that banknotes that are jammed can be completely freed and taken away.
The wire connection between the banknote or coin hopper may be malfunctioning. Check the control board if the change machine display is incorrect or blank after a banknote is accepted.
Putting tools or using your hands to grab items in the change machine may cause damage to it and injury to yourself.