CHAPTER 11 TROUBLESHOOTINGCOPYRIGHT © 1997 CANON INC. CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON) 11-8724 DC power is absent.CauseAC powersupplyFuseDC power suplyPCBWiring, DC loadChecksIs AC power present betweenJ631-1 and J631-4 and J631-2and J631-5 on the DC powersupply PCB?Has the fuse on the DC powersupply PCB blown?Turn off the power switch, anddisconnect the power plug.Connect the power plug in about 1min, and turn on the switch. Is DCpower present?Turn off the power switch, anddisconnect J632, J633, J634, andJ635 from the DC power supplyPCB.Turn on the power switch, andmeasure the voltage between theterminals shown in Table 11-401.Is it normal?Step1234YES/NONOYESYESNOYESActionSee “AC power isabsent.”Remove the cause, andreplace the DC powersupply PCB.End.Replace the DC powersupply PCB.Turn off the powerswitch, and connect oneof the connectors; then,turn on the powerswitch.Repeat this for allconnectors to find theconnector that turns onthe protection circuit.Then, check the wiringfrom that connector tothe DC load.
