Serial Port (Main); Monitor/Power Supply Components Functional Description; Serial Port (Main) Diagram - Wyse WY-120 Maintenance Manual

4-8
Serial Port (MAIN)
Figure 4-7 Serial Port (MAIN)
Diagram
MONITOR/POWER SUPPLY
COMPONENTS FUNCTIONAL
DESCRIPTION
Theory of Operations
The 8032 microcontroller's internal UART is buffered through a
MC1488 RS-232 line driver and MC1489A RS-232 line receiver
(Figure 4-7).
MC14BB
A27
B
ATS
'#
C2
MC14BB
A26
2
TXD
3
U10
C11
MC1488
13
OTA
20
12
P1
MAIN
'#
Port
MC1489
0825
3
A25
4
6
AxD
U7
GND
7
+SV
MC1489
5
A23
10
8
CTS A13
U7
2
1 C4
i2
+SV
MC1489
R24
13 11
A12
DCD 8
U7
2
1
cs
~
The terminal PCB contains both monitor and power supply
circuitry. The monitor circuitry controls the video image on the
CRT screen. The power supply circuitry provides the voltages for
all the logic. Figure 4-8 is a functional block diagram of the
monitor and power supply circuitry. Note that each block is
numbered. This number corresponds with the item number in the
following descriptions.