Microcontroller Input Signal Check - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

MU~OI i O - 1 3 / 1 t . l i x u u v / i - i > u
m n i n i L l i n n t L
4.3.4.25 Synthesizer Interface/Memory, A6A1, (794275) Testing and Troubleshooting
Synthesizer Interface/Memory Testing and Troubleshooting includes a
checkout procedure and fault isolation information. A Digital Voltmeter and a
wideband Oscilloscope (Table 4-1) are required to perform the tests outlined below.
The testing and troubleshooting information in this paragraph is keyed to
several fault isolation tables. These tables are used to isolate the module fault to a
defective integrated circuit or functional group of integrated circuits. Perform the
following procedure in the sequence given. When a. faulty signal is encountered,
replace the key components indicated in the table.
1. Deenergize the receiver.
2. Remove the receiver top cover.
3. Place module A6A1 on an extender card.
4. Set the receiver to the following parameters:
a. Tuned Frequency
b. Bandwidth
c. Gain Mode
d. Detection Mode
e. Tuning Rate
- 15.00500 MHz
50 kHz
AGC FAST
AM
10 Hz
5. Using the oscilloscope, verify the external input signals
to the microcontroller, U18, using the following table.
Table 4-28. Microcontroller Input Signal Check
Test Point Normal Signal Key Components
Comments
U18-X1 Clock signal,
2.078 MHz
Ull, U18
U18-36
+5 Vdc
U11,R6,C9 Powerup Reset
U18-35
+5 Vdc
R7
U18-7
637 kHz
Ull,C10,R10
6. Using the oscilloscope, verify microcontroller Ul data
bus and control signal activity using the following table.
4-47