CHAPTER 7 EXTERNALS/AUXILIARY MECHANISMSCOPYRIGHT © 1999 CANON INC. CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON) 7-1I. POWER SUPPLYA. AC Driver DC Power Supply1. OutlineThe AC driver/DC power supply PCB is supplied with AC power when the door switch (DS1)and the power switch (SW1) go ON.On the other hand, the DC power supply supplies the main body with 24 VDC and 5 VDC.24 VDC is used to drive the scanner motor (M2), main motor (M1), mirror motor (M3) fansand solenoids as well as high-voltage transformer (HVT); 5 VDC is used by the sensors and ICs onthe DC controller PCB.2. DC Power Supply CircuitThe 24 VDC output voltage is generated by a S.M.P.S*. The 5V is derived by a step-downcircuit from the 24V DC output.The S.M.P.S. and the step-down circuit are provided with an overcurrent and overvoltage pro-tection mechanisms and are used to maintain the output voltage stable against line load variations.3. AC Drive CircuitThe DC power supply/AC drive PCB has an AC driver circuit and, based on the signals fromthe DC controller PCB, controls the SSRs and relays on the DC power supply/AC drive PCB todrive AC loads.If the DC controller PCB detects an error, the ACOFF signal is generated to turn the relay(SK101) on the DC power supply/AC drive PCB OFF, thereby shutting off the power to the LDNand the fixing heater.When the power is shut off, switch the copier OFF, and identify the cause; then, switch thecopier OFF.Note that repeated short-circuiting and resetting can cause the built-in fuse to blow.* S.M.P.S.; Switching mode power supply.
