Lexmark Optra C710 Service Manual - Page 162

5016-001 Serial Port Service Check Run the "Serial Wrap Test" on page 3-14. The Serial Wrap Test is designed to check the serial port hardware, by using a wrap plug (P/N 1329048) which invokes the Serial Post Diagnostic Test. The test isolates the printer from the serial cable and host, displaying failure information for approximately three seconds. If the test indicates a problem, replace the controller board. Toner Level Detect Service Check Note: The toner level sensor is mounted on the same board as the new cartridge detect sensor and is located in the bottom of the printer. The toner cartridge contains two mirrors mounted behind a window in the cartridge that reflect infrared light from an LED, mounted on the sensor board, back to a photo transistor also mounted on the sensor board. The printer does not detect the level of toner left in the cartridge. FRU 1 Toner Cartridge 2 Toner Level/ New Cartridge Detect Sensor Board Engine Board TE Cable Action Try a new cartridge for cartridges for which the level of toner, has not been sensed. Check the sensor board assembly for signs of excessive toner, paper dust or other contaminants. Blow off contaminants with clean dry air. If the sensor board is clean, replace the FRUs in the following order: 1. Toner level/new cartridge detect sensor board 2. Engine board 3. TE cable 2-96 Service Manual