Canon ImageRunner iR8500 Series, Service Manual, Page: 545 / 1122

Chapter 11
11-15
11.4 Power Supply System
11.4.1 Power Supply
11.4.1.1 Outline of the Power Supply
0007-0790
iR105i/iR105+ / iR9070 / iR85+ / iR8070
The machine's DC power is supplied by the DC power supply PCB and the relay PCB.
T-11-17
11.4.2 Protection Function
11.4.2.1 Protective Functions
0007-0808
iR105i/iR105+ / iR9070 / iR85+ / iR8070
The machine is designed to automatically stop the output of the DC power supply as soon as the overcurrent protective mechanism turns on.
If an overcurrent is detected by the overcurrent detection circuit A, outputs [1] and [2] are stopped; this is to prevent malfunction of the machine, as output
[1] is used by the logic system.
If the overcurrent detection circuit B detects an overcurrent, output [2] is stopped.
F-11-12
T-11-18
PCB Function
DC power supply
PCB
Relay PCB
- Generates DC power from AC power.
- Protects against overcurrent.
- Generates DC power from DC power (24V->18V)
- Distributes DC power to loads.
- Protects each load against overcurrent.
Detection by Machine operation Resetting
Overcurrent detection
circuit A Stops outputs [1] and [2]
from the DC power
supply PCB. Turn off the main power switch, and remove the
cause; then, leave the machine alone for about 3
min, and turn on the main power switch.
Output [1]
Converter
circuit 1
3.3V/5V/+8V
-8V/12V/15V
Converter
circuit 2
24V/38V
Sequence
control
circuit
Overcurrent
protection
circuit 1
Overcurrent
protection
circuit 2
Overcurrent
detection
circuit B
Overcurrent
detection
circuit A
5V
12V
3.3V
+8V
-8V
15V
38V
24V
Overcurrent detection signal 1
Overcurrent
detection signal 2
Output stop signal 2
Output stop signal 1
J1701
Output [2]
5
4
DC power supply PCB Relay PCB
Outputs [1] and [2] are stopped.
Output [2] is stopped.