Wavetek 188 Manual page 27

Table 6-2. Power Supplies and Generator Loop (Continued)
Indication: Fuse blown, no power indication or no outputs.
Check Corrective Procedure
4. Check indicator lamp. DS1 and VR2, wiring E34
and E33.
5. Check C4 (+) for +15 Мас. a. VR1.
b. Excessive loading; use
board jumpers to isolate
cause.
6. Check C5 (—) for —15 Vdc. a. Q2.
b. U2, 01.
с. Excessive loading; use
board jumpers to isolate
cause.
7. Check 07 pin 14 for +5 Мас and 07 pin 13 for —5 Vdc. a. Q4, Q3, U2.
b. Excessive loading; use
board jumpers to isolate
cause.
8. Check U4 pin 6 for a dc shift from approximately + 10V to + 15V as the | Go to table 6-7.
frequency dial is rotated from 4.0 to .004. Check U6 pin 8 for a dc shift
from — 10Vto — 15V as the frequencydial is rotated from 4.0 to .004.
9, Check anode CR6 for approximately - 3.5 Мас. Go to table 6-10.
10. If emitter Q11 has a 4 kHz, +1.25V triangle, go to table 6-3.
11. Check for the same voltage at the gate of Q9 as at the emitter of Q11, Q9 - Q11 and associated
within saturation limits of the amplifier. circuitry.
12. If the voltage at the emitter of Q11 is > + 1.25V, check cathode CR10 U7, Q7 and associated
for approximately — 2.5V. If the voltage at the emitter of Q11 is « — 1.25V, circuitry.
check cathode CR10 for approximately + 2.54.
13. Check U5.
Table 6-3. Output Circuits
Indication: Function outputs missing or clipped when TTL sync output OK. Problem with triangle waveform.
T
Check Corrective Procedure
1. Set controls to initial positions (refer to paragraph 6.4). Check for normal operation.
2. Check emitter Q11 for a 4 kHz, + 1.25V triangle. Go to table 6-2.
3. Select triangle function, rotate AMPLITUDE сем, and check U13 pin 10 a. R114 R118 adjustments.
for a +1.25V triangle. b. 013.
c. SW13.
6-3