Chapter 8
385
ADC/Interface Section
Triggering or Video Gating Problems
Triggering or Video Gating Problems
Refer to function block H of A3 Interface Assembly Schematic Diagram
(sheet 3 of 6) in the 8560 E-Series Spectrum Analyzer Component Level
Information.
The 1 MHz ADC clock provides synchronization in FREE RUN and
SINGLE triggering. LINE triggering synchronization originates on the
A6 power supply. Trigger MUX A3U613 selects between FREE RUN,
VIDEO, LINE, and EXTERNAL trigger sources. The trigger signal sets
the output of the HSCAN latch high. HBADC_CLK0 provides the
trigger signal for FREE RUN. The VIDEO TRIG signal must be at least
25 mV (0.25 divisions) peak-to-peak to trigger in video trigger mode.
The 3 MHz video bandwidth is not available when using video gating.
The trigger for Gated Video has two modes of operation, level mode and
edge mode. In the edge mode, positive-edge or negative-edge triggering
can be selected. Output 0 from pin 10 of A3U617 generates the gate
delay and output 1 from pin 13 of A3U617 generates the gate length.
The duration of these two time intervals is set using front-panel
softkeys under the
SWEEP
key. The trigger input for Gated Video is the
rear panel EXT/GATE TRIG INPUT (TTL > 10 k
Ω
).
1. Check that the trigger MUX is receiving the proper trigger source
information by selecting each of the following trigger modes and
checking the TRIG_SOURCE0 and TRIG_SOURCE1 lines as
indicated in
below.
2. If a trigger mode does not work, check that a trigger signal is present
at the appropriate trigger MUX input, as indicated in
.
3. Check that the appropriate trigger MUX input signal is present at
the trigger MUX output (A3U613 pin 7).
4. To check the video trigger level DAC, connect the positive lead of a
DVM to A3J400 pin 1 and the negative DVM lead to A3TP4.
5. Press
TRIG
and
VIDEO
.
6. Press the STEP
▼
key several times while noting the DVM reading
and position of the video trigger level on the screen.
Table 8-5
Trigger MUX Truth Table
Trigger Mode
TRIG_SOURCE0
U613 pin 14
TRIG_SOURCE1
U613 pin 2
MUX Input Pin
Number U613
FREE RUN
L
L
6
VIDEO
H
L
5
LINE
H
H
3
EXTERNAL
L
H
4
Summary of Contents for 8564EC
Page 17: ...25 1 General Information ...
Page 37: ...47 2 Adjustment Diagnostic Software ...
Page 77: ...89 3 Manual Adjustment Procedures ...
Page 129: ...161 3a Manual Adjustment Procedures 3335A Source not Available ...
Page 142: ...175 4 Assembly Replacement ...
Page 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
Page 196: ...259 5 Replaceable Parts ...
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Page 224: ...303 6 Major Assembly and Cable Locations ...
Page 234: ...315 7 General Troubleshooting ...
Page 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Page 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Page 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Page 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
Page 283: ...364 Chapter7 General Troubleshooting Block Diagram Description ...
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Page 286: ......
Page 287: ...377 8 ADC Interface Section ...
Page 291: ...Chapter 8 381 ADC Interface Section Introduction Figure 8 2 A3 Test Connector Pin Locations ...
Page 321: ......
Page 322: ...427 9 IF Section ...
Page 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
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Page 379: ...487 10 Controller Section ...
Page 394: ...521 11 Synthesizer Section ...
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Page 454: ...593 12 RF Section ...
Page 489: ...628 Chapter12 RF Section A15 RF Assembly Figure 12 10 10 MHz TTL Reference at U304 Pin 13 ...
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Page 492: ...633 13 Display Power Supply Section ...
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Page 505: ...671 14 Component Level Information Packets ...
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