Ricoh D146 Service Manual page 1763

System Maintenance
When it is desired to set the current value, the operation is completed by pressing the "Menu" key,
and the display returns to the self-diagnosis screen.
To repeat the setting, or to stop touch panel calibration, press the Return key.
When the Return key is pressed, a + mark is displayed in the first position for performing calibration.
When this display appears, by pressing the Return key again, the display returns to the
self-diagnosis screen.
D148 26 SM