C9148-90909 5 Theory of operation 63
Intermediate PCB
The intermediate PCB connects the copy processor board and the ADF to the scanner controller
board.
Power supply
The power supply converts ac power from the source inlet (power cord) to low-voltage dc power.
Low-voltage power is supplied to various flatbed and ADF components. Low-voltage power from
the power supply consists of +3.3 vdc, +5 vdc, +12 vdc, and +24 vdc voltages.
Table 11. Low-voltage components
Overcurrent and overvoltage protection
The power supply uses overcurrent and overvoltage protection. If a short-circuit on the load side
(flatbed and ADF component side) causes an excessive current or voltage draw, the overcurrent
or overvoltage protection function interrupts the power-supply output. If this happens, turn the
printer off, and then identify and repair the malfunctioning component.
Note The power supply must remain off for at least two minutes for the overcurrent and overvoltage
functions to reset.
A fuse (power supply PCB F101) protects against overcurrent coming from the ac source inlet
(power cord).
Voltage Components
+3.3 vdc ● scanner controller board
● scanner controller-to-engine controller connector
● scanner controller-to-copy processor board intermediate PCB
● CCD drive circuit
● document-detect sensor
● leading-edge sensor
● optical unit home-position sensor
+5 vdc
● scanner controller board
● scanner controller-to-video controller connector
● CCD drive circuit
+12 vdc
● scanner controller board
● CCD drive circuit
+24 vdc
● scanner controller board
● document-pickup solenoid
● ADF motor
● optical-unit motor
● flatbed intake fan
● inverter circuit
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