Troubleshooting Trianglewave Generator And Bca Output Stage - Crown CE-4000 Service Manual

130485-1 Rev. B
5. Connect half wave rectifi ed AC power fl yback and
power it up through an isolation transformer as
shown in Figure 4.
Warning: NOT using an isolation transformer in
Step 5 can result in test equipment damage.
Figure 4.8 Half-Wave Rectifi ed Flyback
6. Using a multimeter check DC supplies on power
supply side. Confi rm TP6, TP7 and TP8 = +15V, TP46
= +7.5V, TP252 =19.0V, U2 pin 11 = 5.1V, and TP256
and U14 pin 1 = 5.0V. All measurements should be
made with respect to SMPS reference (TP2).
7. Using a multimeter check DC supplies on audio
side. Confirm TP254 is +15V, TP255 is -15V and
TP257 is 5.0V. All measurements should be made
with respect to AGND (TP-105).
4.4.2 Troubleshooting Trianglewave Generator and
BCA Output Stage.
1. Using an oscilloscope check audio side triangle
waveforms at TP102 with respect to TP105
(see Figure 4.9).
Figure 4.9 Output Signal of Triangle-Wave Generator
©2002 Crown Audio, Inc.
2. Using an oscilloscope check audio side triangle
waveforms at TP202 with respect to TP205 (see
Figure 4.9).
3. Using an oscilloscope check BCA output stage
gate switching (see Figure 4.10). Probe at each gate
drive resistor.
R360 for Q107 and Q110 (Figure 4.10) while R357 for
Q108 and Q111 (Figure 4.11) of Vp Channel 1.
R365 for Q108 and Q112 (Figure 4.10) while R368 for
Q109 and Q113 (Figure 4.11) of Vn Channel 1.
R460 for Q207 and Q210 (Figure 4.10) while R457 for
Q208 and Q211 (Figure 4.11) of Vp Channel 2.
R465 for Q208 and Q212 (Figure 4.10) while R468 for
Q209 and Q213 (Figure 4.11) of Vn Channel 2.
A total of four measurements for each channel, 2 for
each Vp and Vn sides.
Figure 4.10 Gate Switching, View A
Figure 4.11 Gate Switching, View B
CE 4000 Service Manual
Maintenance 4-5