It’s not uncommon for the 500’s to display 'Wrong Charger' from time to time. The main reason that this error is occurring is an incorrect charger is plugged in or an internal error has occurred. First verify that you are using a X-rite Charger, here is a list of current part numbers SE30-81, SE30-77, SE30-177 and SE30-277. If do not have a X-rite charger you can order by phone at 888-826-3059. If you are using the correct charger and the error is still occuring reset the unit by pressing and holding up arrow, down arrow, and the X button and selecting Yes to load defaults. With resetting all data on 500 will be lost include any stored standards.
