Lexmark C720 Service Manual - Page 191

5024-001 Diagnostic Mode To enter the diagnostic mode: 1. Turn the printer Off. 2. Press and hold the Go and Return buttons. 3. Turn the printer On. 4. Release the buttons when "Performing Self Test" displays on the operator panel. The tests display on the operator panel in the order shown: • Print registration - Setting Tray 2 left margin - Setting top margin • Print tests - Tray 1 - Tray 2 (displayed only if Tray 2 is installed) - Print quality pages • Hardware tests - LCD test (operator panel) - Button test (operator panel) - Check engine NVRAM - ROM memory test - Parallel wrap test - Parallel 1, 2, or 3 wrap test (displayed only if a parallel port is available via PC1 in slot 1, 2 or 3) - Serial wrap test (displayed only if the printer supports a standard serial port - Serial 1, 2 or 3 wrap test (displayed only if a serial port is available using PC1 slot 1, 2 or 3) • Duplex tests (displayed only if installed) - Duplex left margin • Device tests (displayed only if the flash or disk options are installed - Quick disk test - Disk test/clean - Flash test Diagnostic Aids 3-5