Chapter 7 Externals/Auxiliary Mechanisms; Power Supply; Ac Power/Dc Power Supply - Canon NP6320 Service Manual

I. POWER SUPPLY
A.

AC Power/DC Power Supply

1. Outline
The power supply PCB is supplied with AC power when the door switch (SW2) 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 main motor (M1), the scanner motor (M2), fans and solenoids as
well as high-voltage transformer (HVT); 5 VDC is used by the sensors and ICs on the DC control-
ler PCB.
2. DC Power Supply Circuit
The 24 VDC for the DC power supply is supplied by the switching regulator.
The 5 VDC, on the other hand, is supplied by the DC/DC converter after conversion from 24
VDC.
The DC/DC converter generates the reset signal (RESET) after power-on and until the 5VDC
supply stabilizes to reset the microprocessor, thereby preventing malfunction of the micro proces-
sor.
3. AC Drive Circuit
The power supply PCB has an AC driver circuit and, based on the signals from the DC control-
ler PCB, controls the SSR and relays on the power supply PCB to drive AC loads.
If the DC controller PCB detects an error, the ACOFF* signal is generated to turn the relay
(K101) on the power supply PCB OFF, thereby shutting off the power to the lamp driver, the paper
deck pedestal, and the fixing heater.
When the power is shut off, switch the copier OFF, and identify the cause; then, switch the
copier OFF.
At the same time, the 'PW-ON-OFF' signal is generated from the DC controller PCB to shut-
off the main switch.
Note:
• The tolerances for the DC power supply are as follows:
+24V ±4%
+ 5 V ±3%
• Repeated short-circuiting and resetting can cause the built-in fuse to blow.
COPYRIGHT © 1999 CANON INC.

CHAPTER 7 EXTERNALS/AUXILIARY MECHANISMS

CANON NP6320 REV.0 DEC. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
7-1