Yamaha Disklavier MX100A Product Handbook page 88

DGPS, DKVPRO, MARKIII (1-beam 4-points)
For all except the PRO, use "HAMMER SENSOR HEIGHT TEST" on the SENSOR SHEET menu.
For the PRO, use "HAMMER SENSOR HEIGHT TEST" on the "Sensor unit test" menu.
(2) HMR TEST
KEY NUMBER = XX
Slowly advance the hammer toward the stopper, and
ON
check points H1 to H4 (buzzer ON and OFF).
REST
H1
H2
H3
H4
Confirm that H4 occurs when the hammer is 1.5 mm
away from the strings. For silent mode, confirm that the
hammer advances through H3 (so that the second buzzer
comes on.)
II-36
1st buzzer ON
1st buzzer OFF
2nd buzzer ON
2nd buzzer OFF