Epson Photo PC-750Z, Руководство по обслуживанию, Страница: 26 / 94

EPSON PhotoPC-750Z Revision A
Operating principles Board Component 26
2.1.1.2 CA2 board
Major circuits on the CA2 board are following.
Table 2-3. Major Circuits on the CA2 board
2.1.1.3 ST1 Board
ST1 board has mainly 2 blocks; power supply circuit part and
STROBE(flash) control circuit part.
Table 2-4. ST1 Board
There are 2 blocks in the strobe(flash) control circuit part; Charging
circuit part and Discharging (Light emission) circuit. Each block is
explained on the next page.
No. Name Function
1 Digital Clamp
The optical black section of the CCD extracts
averaged values from the subsequent data to
make the the black level of the CCD output data
uniform for each line. The optical black section of
the CCD averaged value for each line is taken as
the sum of the value for the previous line multiplied
by the coefficient k and the value of for the current
line multiplied by the coefficient 1-k.
2 Signal Processor Generic name of No.3 to 6 circuits below.
3
γ
correction circuit
This circuit performs (gamma) correction in order to
maintain a linear relationship between the light
input to the camera and the light output from the
picture screen.
4 Color generation circuit This circuit converts the CCD data to RGB signals.
5 Matrix circuit
This circuit generates Y, R-Y, and B-Y signals from
the RGB signal.
6
Horizon/Perpendicular
Aperture
This circuit generates aperture signal.
7
AE/AWB, AF arithmetic
(computing) circuit
The AE/AWB carries out computation based on 64-
segment screen, and the AF carries out
computations based on a 6-segment screen.
8 SDRAM Controller
This circuit outputs address, RAS, CAS and AS
data for controlling the SDRAM. It also refreshes
the SDRAM.
9 Communication circuit Generic name of No.10- to 12 circuits below.
10 USTART circuit
The RS-232C can be used for both synchronous
and asynchronous transmission.
11 SIO circuit Interface for the 4-bit microprocessor.
12 PIO/PWM/LCD
8-bit parallel input and output makes it possible to
switch between individual input/output and PWM
input/output.
13 Digital encorder
It generates chroma signal from color difference
signal.
14 JPEG control circuit
Controls the interface for the externally-connected
JPEG IC.
No. IC No. Function
1 IC501
This IC has PWM type 4-ch switching regulator circuit;
CH1: Digital 5V, analog system (5V, 15V, -7.5V, 5V (A))
CH2: Digital 3.3V
CH3: Analog voltage LCD system, (5V, 12V, 15.5V)
CH4: Back light
This regulator has short-circuit protection circuit and
Mis-operation prevention circuit for low input voltage as
safety circuits.
2 T3101 Pressure rise/fall transformer for Analog output voltage
3 T3103 Pressure rise transformer for LCD drive voltage output
No. Name Function