Ricoh A151 Field Service Manual page 226

Check the voltage at CN105-2 to 5 on the main board when the
main switch is turned on.
17 volts 24 volts
Replace the main board.
Replace the scanner motor.
Check that CN103 and CN105 on the main board are correctly connected.
Correct Incorrect
Connect CN103 and CN105
Is there 0 volts at CN103-11 on the main board when the scanner H.P.
sensor is deactuated?
No Yes
Replace the main hoard
Check if the dc harness (signal line) for the sensor is defective.
No Defective
Replace the dc harness.
Replace the scanner H.P. sensor
A151/A152 6-32 FSM