1St Lo Synthesizer Fault Isolation Chart - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

Wd-BYiB-iy/r r. n r i v L u t i v n a
MAINTENANCE
Table 4-5. 1st LO Synthesizer Fault Isolation Chart
Test Point
Normal Signal Key Components
Comments
E12
1 MHz clock, TTL
Time Base
Ell Pulse train when
tuning with wheel
A6A1 Check or
replace A6A1
Ul-3
Approx. 5.73 MHz
U3, U4
Prescaler
Ul-16,17 Short, 5 V spikes
Ul
Synthesizer
E5 +3 Vdc
U2
Tuning Voltage
E2
0 Vdc
U5-U7
E3 +5 Vdc n
E4
0 Vdc n
E2
+5 Vdc ti
Tune receiver to 76
.5 MHz
E3 0 Vdc
ti
E4
+5 Vdc
ti
4.3.4.5
VCO, FE-A1A1A2, (370690) Testing and Troubleshooting
VCO Testing and Troubleshooting includes a checkout procedure and fault
isolation information. A Frequency Counter 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 4-6 for fault isolation.
1. Deenergize the receiver.
2. Disconnect W2P2 from FE-A2J2. Connect P2 to the
frequency counter.
3. Set the receiver front panel controls as follows:
a. Gain Mode-
b. RF Gain -
Manual
Maximum Clockwise
4-19