Microcontroller Bus Activity Check - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

MAINTENANCE
WJ-8718-19/FE HF RECEIVER
4-48
Table 4-29. Microcontroller Bus Activity Check
Test Point
U18 pin 21-28
U18 pin 12-19
U18-31,32
U18-30
Normal Signal
Pulse train,
less than 1 us
prr.
Pulse train,
less than 1 us
prr.
Pulse train,
less than 1 us
prr.
Pulse train,
0.4 us prr
Key Components
U18,U4,U5,U6,U7,
U8
Comments
7. Using the oscilloscope, verify I/O signal activity
using the following table.
Table 4-30. CPU I/O Signal Check
Test Point Normal Signal
Key Components
Comments
U6 pin 2-19
Pulse train,
less than 1 us
prr.
Pulse train,
less than 1 us
prr.
Square wave,
1 ms prr.
Square wave,
1 ms prr.
U6
Address Latch
Data/Address Latch
Address Decoder
Address Decoder
U4 pin 2-9
U4
U7 pin 11,13,
14,15
U8 pin 10-15
U7
U8,U9
Using the oscilloscope, verify the RF Frequency and
BFO Frequency outputs using the following table. If
any faulty signals are encountered, replace the
integrated circuit associated with that signal as
indicated in the table.