Table of Contents
Advertisement
6.5.1
Amplitude
Modulation
at
FUNC
OUT
Distorted or Missing
Improperly set controls:
1. AUX GEN MODE and FUNC (Main Generator)
switches must be set to AM.
2. WIDTH/LlF/LlM vernier must not be fully ccw.
3. AUX GEN and main generator frequency too low.
4. MODE (Main Generator) switch incorrectly set to
TRIG or GATE.
5. Combination of OUTPUTADEN and AMPLITUDE
controls excessively reducing signal.
6. DC OFFSET overdriving amplifier.
Functional block isolation:
If the amplitude modulated signal at the function out is
distorted or missing, refer to figure 6-22.
6.5.3
6.5.2
6.5.1
Amplitude Modulation At FUNC OUT
Distorted or Missing
All Waveforms At AUX OUT Distorted
or Missing
Output At AUX SYNC OUT Distorted or
Missing
Loop Will Not Oscillate
Abnormal Waveforms (AUX OUT)
Waveform Symmetry Out of Specification
Incorrect Frequencies
Loop Oscillates In AUX GEN OFF MODE
AUX VCG Input Has No Effect
Variable Symmetry Bad
No Internal FM
Paragraph
6.5.4
6.5.5
6.5.6
6.5.7
6.5.8
6.5.9
6.5.10
6.5.11
Symptom
1. Identify improperly set controls.
2. Isolate the faulty functional blocks.
3. Identify the faulty circuit or component.
Individual component troubleshooting is given in para-
graph 6.7, recommended test equipment is given in
paragraph 5.2 and circuit schematics are in the back
of this manual.
In all problems:
1. Double check for proper control settings.
2. Calibrate or rule out calibration as a problem.
3. Inspect components, wiring and circuit boards for
heat damage.
4. Recalibrate as necessary after circuit repair.
Find the instrument symptom in table 6-16 and pro-
ceed as directed to the proper troubleshooting
paragraph.
Table 6·16. Sweep/Mod Board Related Problems
6-18
Table 6-16 gives an index of common sweep/mod
board symptoms. For each symptom a troubleshoot-
ing guide is referenced (Paragraphs 6.5.1 through
6.5.11) that, when correctly followed, will lead to a
solution to the problem.
The troubleshooting guide is arranged in three (3)
levels:
6.5
SWEEP/MOD BOARD TROUBLESHOOTING
WARNING
With the covers removed, dangerous
voltage points may be exposed. Contact
with any of these points could cause
serious injury or death.
Test Point
Desired Results
033
Collector
- 22.7 ± 2.3 Vdc
Base
+ 18.3 ± 1.8 Vdc
036
Emitter
+ 19 ± 1.9 Vdc
Collector
+ 0.7 ± .07 Vdc
037
Emitter
+ 0.05 ± .003 Vdc
Collector
+ 22.5 ± 2.3 Vdc
038
Emitter
+ 0.05 ± .005 Vdc
CR27
Cathode
+23 ± 2.3 Vdc
Anode
+ 0.6 ± .06 Vdc
VR5
Input
+31 ± 3.1 Vdc
Output
+24 ± 2.4 Vdc
034
Collector
+ 22.8 ± 2.3 Vdc
Base
- 18.3 ± 1.8 Vdc
039
Emitter
-19
± 1.9 Vdc
Collector
- 0.05 ± .005 Vdc
040
Emitter
- 0.05 ± .005 Vdc
Collector
-21
± 2.1 Vdc
041
Emitter
- 0.05 ± .005 Vdc
CR28
Anode
-23
± 2.3 Vdc
035
Base
- 0.6 ± .06 Vdc
IN
- 31 ± 3.1 Vdc
VR6
ADJ
-21.3
± 2.1 Vdc
OUT
- 23.6 ± 2.4 Vdc
U2
Pin 2
0.0 ± 10 mVdc
Pin 6
- 0.05 ± .005 Vdc
Table 6·15.
Output Amplifier Checks (Continued)
Advertisement
Table of Contents
Troubleshooting
