AL-1566 (serv.man15). Electrical section - Sharp Copying Equipment Service Manual (repair manual). Page 11

AL-1556/1566  ELECTRICAL SECTION  12 - 11

The NIC PWB is used to realize 10Base-T network functions (print
only). It is provided with the CPU, the Ether chip, FPGA, memory, and
the RJ45LAN connector. Data are converted into IEEE1284 parallel
data and sent to the MCU PWB, realizing network functions.

The operation circuit is composed of the LCD control circuit, the key
matrix circuit, the display matrix circuit, and the buzzer circuit, realizing
the U/I functions.

The character LCD (COG) in 2 lines and 16 digits is used. The display
data are sent from the MCU (CPU) to LCD internal registers, control-
ling the LCD.

The SEL signal is sent from the CPU of MCU to the matrix selector IC
(multiplexer) in the operation circuit. The signal detects OFF/ON of the
key, and is sent to the CPU as serial data.

The display is controlled by inputting the serial data signal, the clock
signal, and the latch signal from ASIC to the LED driver in the opera-
tion circuit.

In the LED driver, data are set to the register (8bit) and latched to con-
trol the IC output port, performing matrix-driving of ON/OFF of the LED.

The carriage unit is provided with the CCD PWB, the inverter PWB, the
lamps, etc. A document is radiated, and image data read by the CCD
are A/D converted to be sent to the ASIC.

The color image sensor uPD8861 (5400 pixels x 3 lines) is used as the
CCD on the CCD PWB to scan images in the resolution of 600dpi/US
letter size in the main scanning direction.

Image data scanned by the CCD are inputted to AFE (AD9826), where
they are A/D-converted to output digital data. The output digital data
are sent to the MCU PWB and to the ASIC. The ASIC performs image
process with the digital data.

The transformer is controlled by the lamp control signal from the MCU
PWB to turn ON/OFF the cool cathode ray tube by the transformer out-
put.

The DC power circuit directly rectifies the AC power and performs
switching-conversion with the DC/DC converter circuit, and rectifies
and smoothes again to generate a DC voltage.

The constant voltage control circuit is of +5VEN. +24V and +12V are of
the non-control system by winding from the +5VEN winding.  As shown
in fig (1), +24V, +12V, and +5V are provided with the ON/OFF function
by external signals. +3.3V is outputted from +5VEN to the regulator IC.

Refer to the block diagram, fig (1).

fig (1) Block diagram

Noise filter

circuit

Rush current

prevention circuit

Rectifying/
smoothing

circuit

Inverter circuit

(Ringing choke converter system)

Rectifying/

smoothing circuit

(Semiconductor switch)

Rectifying/

smoothing circuit

+12V regulator IC

(with ON/OFF function)

Overcurrent
protection circuit

Control
circuit

Constant-voltage
detection circuit

(Semiconductor switch)

+3.3V

regulator IC