Wavetek 193 Instruction Manual page 56

Functional block isolation:
1. Set FREO/START FREOto 2.0, FREOMULT to 1
K,
and VCG IN with no input. Measure voltage
across R86 and R97 (
+
3.8 Vdc). In addition, as
the frequency dial is rotated, the voltage linearly
6.3.13 Voltage At VCG IN Connector Not Chang.
ing Frequency Properly
Improperly set controls:
1. Excessive VCG IN voltage for dial setting (maxi-
mum input voltage is
+
5.0 Vdc with FREO/START
FREO set at .02 and the Freq VERNIER turned
ccw).
2. MODE (AUX GEN) incorrectly set to FM
12 o'clock TRIG LEVEL:
Set the scope as follows:
Horizontal: 20 ns/div
Vertical: 1 V/div
Inject a 15 MHz 1 Vp-p trigger signal and refer to
figure 6-9.
6-8
Functional block isolation:
1. Verify power supply voltages are within ± 5% of
nominal, with less than 100 mVp-p of ac ripple.
If
not, refer to paragraph 6.4.1.
2. If the trigger baseline cannot be calibrated within
specification, set MODE to GATEand monitor the
emitter of 019. With TRIG IN disconnected, rotate
the TRIG LEVELccw. The voltage should go about
- 0.7 Vdc. Rotating the TRIG LEVEL cw should
change this voltage to about
+
1.8 Vdc. If these
voltage readings are normal, check CR18 and
CR19.
3. If none of the above conditions apply, refer to
figure 6-8.
4. For high frequency (1M and 10M ranges) trigger
or gate problems, set the controls as follows:
FREO/STARTFREO 2.0
FREO MULT: 10M
SYM: OFF
MODE: TRIG or GATE
(Depends on symptom-
GATE preferred)
Figure 6-7. Frequency Accuracy Troubleshooting
CHECK U7
AND CURRENT
SOURCE GUIDE
6.4.2
CHECK US
AND CURRENT
SOURCE GUIDE
6.4.2
CHECK U13,
015 AND CURRENT
SOURCE GUIDE
6.4.2
CHECK U13,
014 AND
CURRENT
SOURCE GUIDE
6.4.2
CHECK U14
PINS 5,6,7
AND CURRENT
SOURCE GUIDE
6.4.2