Canon NP6621 Service Manual

Also see for NP6621: Service manual Service handbook

Contents

3–37OPERATIONS AND TIMINGCOPYRIGHT © 1998 CANON INC. CANON NP6621 REV.0 FEB. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)The machine exerts phase control by the zero-cross signal (ZXDP) to stabilize the light intensity.The intensity of the scanning lamp is switchedcontrolled by the LIGHT INTENSITY CONTROLcommand (FLS).During AE exposure, however, the voltage (70V) applied to the scanning lamp remains the same.The NP6621 adjusts the copy density using itsdevelopment bias; see p. 3-26.c. Error ProtectionThe condition of the scanning lamp is monitoredusing the LIGHT signal (LGHT).If the LIGHT signal (LGHT) is received by theDC controler for about 20 sec, the error detectioncircuit generates the AC SHUTOFF signal (ACOFF)to force the relay (K1) on the AC driver OFF, therebycutting AC power supply (p. 3-101). In this case,E220 error is displayed.C. Controlling the ScanningLamp1. OutlineThe scanning lamp (LA1) is controlled by the DCcontroller PCB; see Figure 3-303. Specifically, theDC controller:• Turns the scanning lamp ON and OFF.• Controls the intensity of the scanning lamp.2. Mechanisma. Turning the Scanning Lamp ON and OFFThe CPU (Q308) on the DC controller PCBcontrols the lamp regulator. The scanning lampgoes ON/OFF through serial communicationinterface between DC controller PCB and Compositepower supply PCB.b. Controlling the Intensity of the ScanningLampFigure 3-303Lamp ONdetectioncircuitACOFFJ307-2J307-4 LGHTJ5-11-6 FLS-13 ZXDP -2-9W15W4-3J3-1CPU (Q308)Error detectioncircuitIntensityswitchingcircuitPhasecontrolTriac-triggeringcircuitSwitchingcircuitComposite power supplyDC controller PCBRelay(K1)Power SupplyScanninglamp(LA1)Zero-crossdetectioncircuitDownload service manual and resetter printer at http://printer1.blogspot.com