Lexmark T520 Service Manual - Page 74

4520-xxx POST fails, 230 Paper Jam, Check Duplex message displays. FRU 1 Duplex D.C. Servo Drive Motor 2 Input Sensor, Input Sensor Flag 3 Paper Exit Sensor and Flag Action Check the D.C. servo motor cables for signs of cuts or other damage. Check the D.C. servo motor sensor cable connector for pin damage. If no problem is found, replace the FRUs in the following order: 1. D.C. motor assembly 2. Duplex unit system board Run the Duplex Sensor Test from the diagnostics menu. If the test fails, check the input sensor cable at J5 on the system board for correct installation. If no problem is found, replace the FRUs in the following order: 1. Input sensor assembly 2. Duplex unit system board Check the duplex exit sensor for correct installation and free movement of the sensor flag. Check to make sure the sensor cable is connected to J8 on the system board. If no problem is found, replace the FRUs in the following order: 1. Exit sensor assembly 2. Duplex unit system board 2-46 Service Manual