Toshiba DP120F, Service Manual

Page: 403 / 706

DP120F/DP125F Circuit Description 7-94 March 2000 © TOSHIBA TEC
The Operation panel PBA consists of the I/O GA (IC1), LED’s, key switches, LCD, LCD drivers
(IC2-4), and other peripheral devices. It detects the pressed status of each key switch and
controls the lighting and display of the LCD and LED’s. It is connected to CN19 on the Mother
PBA.
Data communication is carried out between the Mother PBA and Operation panel PBA through
OD0-7 and OA1-4.
Lighting of the LED’s is controlled by the lighting signal output by the I/O GA according to the
OD0-7 signal output from the Main PBA. The I/O GA causes the LED2-6 and 9-14 signals to
be HIGH to turn on Q1-12 and 15. This allows voltage to be applied to LED’s 2-6 and 9-14 to
light the LED’s.
Display of the LCD is performed by the LCD drivers (IC2-4) which output the LCDCOM1-64
and LCDSEG1-160 signal according to the OD0-7 signals output from the Main PBA.
For detection of the pressed status of each key switch, the I/O GA causes one of the SWS1-11
signals to be LOW. It is detected that the status is off if the corresponding one of the SWC1-8
signals output through the key switch is at HIGH level, and on if at LOW level.
Signal Name Type Active Description Destination
OD0-7 I/O - I/O Data Bus IC254
OA1-4 I - I/O Address Bus IC60
LED2-6, O H LED Lighting Control Signals 2-6, 9-14 Q1-5, 8-12, 15
9-14
LCDCOM O - LCD Common Signals 1-64 LCD
1-64
LCDSEG O - LCD Segment Signals 1-160 LCD
1-160
SWS1-11 O L Key Switch Detect Output Signals 1-11 Each key
switch
SWC1-8 O H Key Switch Detect Input Signals 1-8 I/O GA
01/08