126 Phaser 5400 Laser Printer Service GuideRAP 46 Inoperative KeypadControl Panel is not operative.Table 73 Inoperative Keypad Troubleshooting ProcedureStep Actions and Questions Yes No1 PROCEDURE1. Enter Diagnostics mode.2. From the Main Menu, select Component Test / SensorInput / press [4] to start, [0] to stop.Does the printer enter the Diagnostics mode tothe Sensor Input level?Go toStep 4.Go toStep 2.2 SYSTEM CONTROLLER BOARD P/J18 VOLTAGECHECK1. Disconnect P/J18 on the System Controller Board.2. Measure the voltages listed in Table 74, between P18on the System Controller Board and frame ground.Are all voltages correct per Table 74?Go toStep 3.Replace theSystemControllerBoard[RRP 8.1,page 305].3 CONTINUITY CHECK1. Disconnect P/J421 from the Control Panel.2. Perform a continuity check on all wires from P/J421and P/J18.Do all wires check OK for continuity?Replace theControlPanelAssembly[PL 1.1,page 384].Replace theWiringHarness[PL 9.1,page 404].4 KEYPAD TESTPress keypad buttons (1-3 and 5-7) while observing theLCD.Note: Keypad numbers increment the LCD counter.Keypad [4] enters the test and [0] stops thetest.Does the LCD counter increment each time youpress Keypad numbers (1-3 and 5-7)?Replace theSystemControllerBoard[RRP 8.1,page 305].Replace theControlPanelAssembly[PL 1.1,page 384].5 SUSPECT COMPONENTSThe following printer components and areas areassociated with this specific problem. One or more ofthese components or areas may have failed partially orcompletely. If you cannot isolate this problem using thesteps in this Repair Analysis Procedure, replace eachcomponent or troubleshoot each area listed below, oneat a time, until you isolate and solve the problem. Control Panel Assembly [PL 1.1, page 384] Wiring Harness Assembly, System Controller Board toControl Panel [PL 9.1, page 404] Wiring Harness Assembly, System Controller Board3.3 V [PL 9.1, page 404] Power Supply [PL 9.1, page 404]
