Circuit Description Of Operation Panel Pwb - Sharp AM-900 Service Manual

AM-900U

[6] Circuit description of operation panel PWB

1. Operational description
1) Operation panel PWB
The operation panel PWB consists of 30 keys.
This PWB includes the eight STRB lines (8bit) and the four SEN
lines (4bit). The eight STRB lines are controlled by OA-2000 (CPU)
on control PWB and the four SEN lines return signals to control
PWB. The LED on this PWB is also controlled by LEDON (1bit sig-
nal) from control PWB. The LD (5bit) include signal line for four
LCD data lines and RS line.
2) LCD
The LCD uses the one-chip LCD driver IC to display 16 digits x 1
line. The LCD display density is not controlled.
2. Block diagram
SEN[3:0]
STRB[7:0]
E
R
LED ON
KEY MATRIX
LCD
LD[4:0]
LED
Fig. 36
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