Ricoh A151 Field Service Manual page 237

Yes
Check the voltage at CN114-6 on the main board.
0 volts 24 volts
Replace the main board.
Check the voltage at CN114-4 on the main board.
0 volts 24 volts
Replace the main board.
Check the voltage at CN114-8 on the main board.
24 volts 0 volts
Replace the main board.
Does the thermistor properly contact the hot roller?
Yes No
Correctly position the thermistor.
Does the voltage at TP102 on the main board increase after the main
switch is turned on?
Yes No
Replace the thermistor.
Replace the ac drive board.
FSM 6-43 A151/A152