5-8
CSP-5000E
CSPK-5000E
SYSTEM KEYBOARD MODEL CSPK-5000E
SYSTEM KEYBOARD MODEL CSPK-5000E
Structure
System keyboard, model CSPK-5000E consists of the
following:
Control Board (SY-211)
Key Matrix Board (KIO-9)
Connector Board (IF-511)
JOYBALL Section
LCD Module Section (LM40X21B)
REGULATOR
SYNC DETECTOR
RESET
RAM
(MODULAR-JACK)
RS-422A
(TACT-SWITCH)
(BNC)
(BNC)
(SLIDE-SWITCH)
CABLE COMP
(MINI-JACK)
(PIN-JACK)
(PHONE-JACK)
JOYBALL
UART
POWER
BACKLIGHT
+5V
SWITCH
SPEAKER
MIC
Y
X
VIDEO
DATA
GENERATOR
CHARACTER
IN
AC
POWER
AMP
BUFFER
S/M/L
CONTROL-BUS
ADDRESS-BUS
DATA-BUS
RESET
PRINTER
IN
VIDEO
OUT
VIDEO
RECEIVER/DRIVER
RS-422
COMPENSATOR
CABLE
BOARD
IF-511
+5V
LED
MATRIX
KEY
I/F
I/F
SWITCHING
BOARD
BOARD
KIO-9
SY-211
LCD
ROM
CPU
Circuit Description
Control Board (SY-211)
• The board consists of analog and digital signal circuits.
[Analog signal circuit]
• The DC component of video signals from CN102 are
removed by C103 and forwarded to the subsequent cable
compensation circuit, where IC105’s gain and
frequency-characteristics are adjusted in three steps, S/
M/L, by the switching signals sent from CN103 and set
according to coaxial cables (type/length) being in use.
After the cable compensation circuit, the video signals
go to the character-generator circuit. In the character-
generator circuit, the on-screen-display IC (IC103) adds
characters to the video signals and sends them to the
IF-511 board through CN102. The micro-computer
(IC101) controls IC103. The sync detector signal
available from IC103’s pin
#
13 is integrated by CR
network that follows and is forwarded to the micro-
computer. The micro-computer then reads the signal and
determines whether the video signal is existent (low
level) or non-existent (high level) and switches the
circuit automatically to the external video signal mode or
the internal video signal mode (with blue background).