CANON NP6020
Service Manual

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3. OPERATIONS AND TIMING

V. POWER SUPPLY A. AC Driver/DC Power Supply,
1. Outline The AC driver/DC power supply PCB is supplied with AC power when the door switch (SW2) and the power switch (SWl) 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), fans and solenoids as well as high-voltage transformer (HVT); 5 VDC is used by the sensors and ICs on the DC controller PCB. 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 micro processor, thereby preventing malfunction of the micro processor. 2.

3.

AC Driver Circuit The DC power supply/AC driver PCB has an AC driver circuit and, based on the

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signals from the DC controller PCB, controls the SSRs and relays on the DC power supply/AC driver PCB to drive AC loads. If the DC controller PCB detects an error, the ACOFF signal is generated to turn the relay (KIOI) on the DC power supply/AC driver PCB OFF, thereby shutting off the power to the lamp regulator and the fixing heater. When the power is shut off, switch the copier OFF, and identify the cause; then, switch the copier OFF. Note that repeated short-circuiting and resetting can cause the built-in fuse to blow.