Canon NP6621 Service Handbook

Also see for NP6621: Service manual Service manual

4–12TROUBLESHOOTING MALFUNCTIONSCauseMultifeederpick-upclutch (CL3)Paper guideplate camMultifeederpick-upsolenoid(SL2)DC control-ler PCBStep123ChecksSelect the multifeeder. Does themultifeeder pick-up roller rotate whenthe Copy Start key is pressed?Press the Copy Start key; does thepaper guide plate shift up?Connect the + probe to the J312B-8on the DC controller. Does the voltagechange from about 24 V to about 0 Vwhen the Copy Start key is pressed?RemedyCheck the wiring; if normal,replace the CL3.Check the position of thepaper guide plate cam andthe separation pad. Asnecessary, adjust or replace.Check the wiring; if normal,replace SL2.Replace the DC controller.Yes/NoNOYESYESNO20 Pick-up operation fails (multifeeder).CauseCableForeignmatter onscannerpathCompositepowersupply PCBDC control-ler PCBScannermotorStep12345ChecksIs the scanner drive cable routedcorrectly?Is the scanner rail free of dirt and doesthe scanner move smoothly whenpushed by hand?Set the meter to the 50VDC range.Doe the index of the meter point to 34V when the + probe is connected toJ8-5 and the – probe is connected toJ8-6 on the composite power supplyPCB?Replace the DC controller PCB. Is theproblem corrected?Replace the scanner motor. Is theproblem corrected?RemedyRe-route the cable.Check the scanner rail surfacefor dirt and foreign matter or foran object that comes into contactwith the scanner.See “DC power is absent.”End.End.Yes/NoNONONOYESYES21 The scanner fails to move forward/in reverse.