Wavetek 193 Instruction Manual page 57

6-9
Functional block isolation:
1. Verify power supply voltages are within
±
S% of
nominal with less than 100 mVp-p of ac ripple. If
not, refer to paragraph 6.4.1.
2. Take the following voltage measurements with
the DC OFFSET button depressed and the DC
OFFSET control rotated cw:
a) The junction of R260 and C116 should vary
from
+
B.OVto - B.OV.
b) U2 pin 2 should hold at O.OV.
tracks FREO/STARTFREO settings within ± 3%
full scale. If it functions properly, check R67, R6B,
R69 and associated circuitry, but if not, refer to
paragraph 6.3.11.
6.3.14 DC Offset Not Functioning Correctly
Improperly set controls:
1. Signal peak plus offset exceeding
+
or - 7.SV
(with a SOOload), or
±
1SV open circuit.
2. Check OUTPUTADEN since this also attenuates
output offset.
Figure 6·9. High Frequency Trigger/Gate Troubleshooting
CHECK U12
PINS 2
THROUGH 5
AND ASSOCIATED
CIRCUITRY
CHECK
U4 AND
ASSOCIATED
CIRCUITRY
REFER
TO TRIG
BASELINE GUIDE
6.4.11
Figure 6·8. Trigger Gate Troubleshooting
REFER TO
TRIG BASELINE
GUIDE 6.4.11
YES
YES
CHECK U4
AND TRIGGER
GUIDE 6.4.10
CHECK U12
AND TRIGGER
GUIDE 6.4.10