3-2 Phaser 7400 Color Printer Options Service ManualIntroductionThis section covers the startup, Service Diagnostics, and power supply operations ofthe Finisher, Inverter, Duplex Unit, and Paper Tray options to aid in troubleshootingproblems.Troubleshooting procedures isolate a problem to a specific component orsubassembly. If you go through the procedures and are still unable to solve theproblem, re-read the “Theory of Operation” section for the problem area tounderstand how that section of the option functions.Using Service DiagnosticsService Diagnostics provides tests for most electro-mechanical components. ServiceDiagnostics also contains test procedures. If confronted with an error that requiresmore than a cursory investigation to clear or when directed by a troubleshootingprocedure, use Service Diagnostics to exercise selected sub-assemblies of parts in thevicinity of the reported error.The system monitors sensors located throughout all attached options. Sensor signalsare used to monitor paper handling and mechanical activity along the entire paperpath. As a sheet travels along the paper path, sensors change state temporarily toindicate the sheet’s presence. If the pattern of sensor state changes differs from theexpected timing for a particular paper size and path, the sensor where the timingdifference occurs identifies the error to report.However, having the error message information doesn’t necessarily pinpoint theproblem. Sensor signals locate where, but often cannot identify why. Motors, belts,gears, solenoids, and numerous other parts are involved in paper transport. TheService Diagnostics’ suite of tests and utilities are the best tools available to pinpointthe root cause behind the reported error.
