3–103OPERATIONS AND TIMINGCOPYRIGHT © 1998 CANON INC. CANON NP6621 REV.0 FEB. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)C. Detecting Errors on thePower Supply PCBThe microprocessor (U402) and LED501 on thecomposite power supply PCB checks for errors; ifan error is identified, the microprocessor (U402)communicates with the DC controller to indicate theresults of self diagnosis on the display or to flashLED501 to alert the user.• Communication Error between DC ControllerPCB and Composite Power Supply PCBIf an error occurs in the communication betweenthe DC controller PCB and the composite powersupply PCB, ‘E240’ is indicated as soon as the DCcontroller PCB identifies an error. In addition, LEDis flashed at intervals of 5 sec when the compositepower supply PCB identifies an error.• Data Error in the High-Voltage OutputIf the difference between the actual controlvalue and the setting associated with the highvoltage generated by the microprocessor (U402) ismore than a specific value, the microprocessor(U402) communicates error data to the DC controllerPCB to indicate ‘E064’.• Detecting Overcurrent in the Low-VoltagePower SupplyIf the composite power supply PCB identifies anerror in any of the DC loads or overcurrent causedby wire trapping, the LED is on fixed.
