If a DRO 100 or 200 readout is not responding to one or more key presses, the keypad ribbon cable may have developed a thin layer of corrosion in the connector. To correct this condition, open up the readout and re-seat the ribbon cable.
First remove the four screws from the backside of the readout. On the bottom of the readout, there is a small hole. If you insert a paper clip or similar object through the hole, and by pulling out the front panel, it will then separate from the chassis.
Inside the readout there is a thin plastic ribbon cable coming from the keypad, connecting to an in-line connector on the printed circuit board.
Remove the ribbon cable from the connector and re-seat it back into the connector. Replace the front panel on the cast chassis and replace the screws. Power up the unit and test the operation of the keys.
If you have any additional questions, please contact DRO Technical Support at 847.490.0351.