Phaser 4400 Laser Printer Service Manual 3-17Laser Assembly10 1. Enter Service Diagnostics and select Sensor Tests.2. Scroll to Rear Cover Switch and press OK.3. Open and close the Rear Cover two or three times.Does the indication on the Front Panel displayalternate between Open and Close as you openand close the Rear Cover?Replace theEngine LogicBoard (RRP9.3 onpage 6-89).Replace theRearInterlockSwitch (RRP9.10 onpage 6-97)or Repair orreplace thewiringbetween theEngine LogicBoard andthe RearInterlock.Laser Assembly Troubleshooting ProcedureStep Actions and Questions Yes No1 1. Enter Service Diagnostics and select the Motors/FanTests and press OK.2. Scroll to Laser Scan Motor and press OK.Can you hear the Laser Scan Motor spin up?Go to step 5. Go to step 2.2 1. Switch the printer power OFF.2. Remove the Left Interface Cover (RRP 1.1 onpage 6-6) Left Cover (RRP 1.2 on page 6-7), and theLeft Plate (RRP 1.11 on page 6-16).3. Switch the printer power ON.4. Check the voltage between P/J21 pin 10 on theEngine Logic Board and frame ground.Is the voltage +24.0 VDC?Go to step 4. Go to step 3.3 Check the voltage between P/J28 pin 1 on the EngineLogic Board and frame ground.Is the voltage +24.0 VDC?Replace theEngine LogicBoard (RRP9.3 onpage 6-89).Replace theLVPS (RRP9.5 onpage 6-91).4 1. Enter Service Diagnostics and select the Motors/FanTest.2. Scroll to Laser Scan Motor but do not press OK.3. Check the voltage between P/J21 pin 12 and frameground.4. Press OK to start the Laser Scan Motor test.Does the voltage drop from +5.0 VDC to0.0 VDC?Replace theLaserAssembly(RRP 7.4 onpage 6-82).Replace theEngine LogicBoard (RRP9.3 onpage 6-89).Main Motor Assembly Troubleshooting Procedure (cont'd.)Step Actions and Questions Yes No
