2Nd Lo Synthesizer Fault Isolation Chart - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

Test Point
Ul-3
El
Ul-1
Ul-7,8
U3-6
Ql-D
E3
5. Disconnect the frequency counter and connect the RF
voltmeter. The voltmeter should indicate -2 dBm.
6. If the signal in step 4 and 5 is incorrect, check the
Test Points given in Table 4-7 with an RF Voltmeter
and oscilloscope. When a faulty signal is encountered,
replace the key components indicated and repeat the
Checkout Procedure. Figure 6-8, 2nd LO Synthesizer
Schematic Diagram should be referred to if additional
signal tracing/fault isolation is necessary.
9. When the 2nd LO Synthesizer has been repaired and is
operating satisfactorily, deenergize the receiver and
disconnect test equipment, if no further tests are to be
performed.
Table 4-8. 2nd LO Synthesizer Fault Isolation Chart
Normal Signal
+9 Vdc
1 MHz clock, TTL
Approx. 4.66 MHz
Short, 5 V spikes
+3 Vdc
100 mV sine
100 mV sine
Key Components
U4
U2
Ul
U2
Q1.CR1
Q2
Comments
DC Supply
Time Base
Prescaler
Synthesizer
Tuning Voltage
VCO
u n n i i ^ i _
4-3.4.8 2nd Converter, FE-A1A2A2, (270907) Testing and Troubleshooting
2nd Converter Testing and Troubleshooting includes a checkout procedure
and fault isolation information. A Signal Generator and an RF Voltmeter (see
Table 4-1) are required to perform the tests outlined below.
Perform the following procedure in the sequence given. If any specified
result is not obtained, refer to Table 4-9 for fault isolation.
1. Deenergize the receiver.
2. Connect the signal generator to FE-A1A2-J2. Connect
the RF voltmeter to FE-A1A2-J3.
3. Set the generator to -20 dBm at 42.0000 MHz.
4-23