On occasion a 400 series densitometer will act strangely. It is possible to reset the unit's microprocessor. Often this will eliminate the problem and it will not be necessary to have the unit repaired. Note that an instrument reset will store factory default values in the calibration memory. It will be necessary to perform a full calibration after the unit is restored to operation. To perform a factory reset proceed as follows:
Close and lock the instrument shoe.
Remove the AC adapter (if attached).
Press and hold the center key.
Gently slide the battery door partially open. Lower the door just enough to remove power from the unit. Too far and you will shoot six ni-cad batteries across the room!
Leave the door open for about ten (10) seconds.
While continuing to hold the center key and the shoe, bring the battery door back up into the closed position.
If you are operating only from the AC adaptor, plug it back in at this time.
In approximately five (5) seconds the unit will reset. It will prompt "MEM LOST", or "MEMORY TEST FAIL" and then "NEED CAL". Continue by performing a full calibration (see Related Support). It will be necessary to re-enter the calibration values from the reference card.
See the Related Support for an article on the instrument conditions established by performing the reset.
