Lexmark Optra C710 Service Manual - Page 194

5016-001 FRU 3 Paper Pass Sensor Upper Unit (S2) Action Check the voltages on the duplex upper unit paper pass sensor on connector CN904. Pin # 19 21 23 Voltage Signal DGND UPSN VL Voltage Closed 0 V dc +5 V dc +5 V dc Voltage Open 0 V dc 0 V dc +5 V dc All voltages are approximate values. • If the voltage on pin 23 is incorrect, replace the duplex option controller board. • If the voltage on pin 21 does not change when the sensor is opened and closed, replace the FRUs in the following order: 1. Duplex upper unit paper pass sensor 2. Duplex option controller board I 232 Paper Jam displays. Paper is jammed in the lower rear unit, or the lower unit of the duplex option. FRU 1 Rear Duplex Unit Lower Duplex Unit 2 Lower Transfer Roll Transfer Drive Pulley Transfer Gears Timing Belt Action Check the rear and lower duplex units for pieces of paper or other material that might cause a paper jam. Check all parts associated with paper movement in the rear duplex unit for correct operation and signs of wear, broken parts or binds. Repair or replace as necessary. 2-128 Service Manual