Watkins-Johnson Company WJ-8718A/MFP Instruction Supplement page 134

WJ-8718A/MFP TABLE 4-16
4.1.4.5.1 Asynchronous I/O Board Troubleshooting Procedure
1. Reference the following manual data to support Tables 4-15 and
4-16.
a. Circuit descriptions in paragraph 3.4.1.
b. Location of Components Diagram in Figure 5-13.
c. Schematic Diagram, Figure 6-8.
d. Modular troubleshooting concept, described in
paragraph 4.1.4.1.
2. Recommended test equipment for troubleshooting Asynchronous I/O
Board components are an oscilloscope, digital voltmeter, ohmmeter
(reference the equipment list in the WJ-8718 Series HF Receiver
Instruction Manua!), and the general digital troubleshooting equip-
ment described in paragraph 4.1.3.1 of this supplement.
3. The following information concerns characteristics unique to the
Asynchronous I/O Board and pertinent to troubleshooting efforts.
Table 4-16. Asynchronous I/O Board Support Circuits (232M-A3)
Support Circui t Supports Function
US
UI Baud rate generator
U6A U4 Inverts output of U2
U6B U2 ALE inverter
U7A UI
Converts RTS from TTL to 232/C level
U7B VI DSR buffer
U7C VI Converts TxD from TTL to 232/C level
V8A
VI Converts DTR from TTL to 232/C level
V8B
VI CTS buffer
V8C
VI RxD buffer
V9A
VI Converts RxD from 232/C to TTL level
V9B
VI Converts DSR from 232/C to TTL level
V9C
UI Converts CTS from 232/C to TTL level
VIOA
V7A
RTS buff.er
VIOB
V7C
TxD buffer
VIOC
V8A
DTR buffer
vn
V3
Pull-up resistive network
NOTE:
NV
indicates not used
4.1.4.6 OptionalI/O Interface Modules (488M-A3)
The I/O Interface is primarily responsible for data transfer via the IEEE Standard
488-1975 bus when the WJ-8718A HF Receiver is equipped with the MFP and 488M Options
4-23