Ricoh M281 Series Service Manual page 457

6.5 SERVICE CALL 490-491
6.5.1 SC400 (ENGINE: IMAGING 3: AROUND THE DRUM)
SC No. Type
SC490-00 D
SM
Error Name/Error Condition/Major Cause/Solution
Toner Density Sensor Error
The sensor output value is 930 or more continuously for 5
seconds.

Toner density sensor defective

Toner motor defective

Connect-Left PCB defective

IOB defective

Toner density sensor defective
1. Reconnect the following connectors.

Toner Density Sensor – Drum PCB connector

Drum PCB – Drum Connection PCB connector

Drum Connection PCB – Connect-Left PCB
connector

Connect-Left PCB – IOB connector
2. If the connector is broken, shorted, or grounded,
replace the connector.
3. Check that the gears and rollers of the development
unit are not damaged and rotate smoothly.
4. Replace the development unit.
6-19
Service Call 490-491
D255/D256/M281/M282