Ricoh M052 Service Manual page 430

220 D Laser synchronization detection error 1: LD0
The laser synchronizing detection signal for the start position of the LD
was not output for 500 ms after LDB unit turned on with the polygon motor
rotating normally.
Laser synchronizing detection board harness loose or broken.
Laser synchronization detection board defective
LDB unit defective
BICU defective
221 D Laser synchronization detection error 2: Other than LD0
The laser synchronizing detection signal for the start position of the LD
other than LD0 was not output for 500 ms after LDB unit turned on with the
polygon motor rotating normally.
Laser synchronizing detection board harness loose or broken.
Laser synchronization detection board defective
LDB unit defective
BICU defective
230 D FGATE ON error
The FGATE signal did not assert within the prescribed time. (The BICU
generates the FGATE signal and sends it to the LD unit when the
registration sensor switches on.)
231 D FGATE OFF error
The FGATE signal did not go off within the prescribed time. (The BICU
generates the FGATE signal and sends it to the LD unit when the
registration sensor switches on.)
BICU, Controller board harness loose or broken
BICU defective
Controller board defective
SM 6-7
Service Call Conditions
M052/M053/M054