OKI MC780 plus

1. While pressing the [6] and [8] keys, simultaneously, turn on the power to enter the Maintenance mode.
   Maintenance mode
   Select Number(1-2)
   1.SU
   2.PU
2. Select the PU by press the [2] key, display "DIAGNOSTIC MODE".
   DIAGNOSTICMODE
   XX.XX.XX FACTORY/SHIPPING
3. XXX.XX.XX of the message "DIAGNOSTIC MODE XX.XX.XX" that is displayed on the LCD display area indicates the PU firmware version number. The FACTORY WORKING MODE setup value is displayed in the right of the lower row. S-MODE of "SHIPPING" is displayed normally.
4. Press the [2] key or [8] key to advance to the desired step of each self-diagnostic menu. (The menu items rotate when either the [2] key or [8] key is pressed.)

How to exit the self-diagnostic mode

1. Turn off the power once and back on 10 seconds later.