Chapter 8
391
ADC/Interface Section
A3 Assembly Video Circuits
A3 Assembly Video Circuits
Voltages from A3J101 to the Variable Gain Amplifier on A3 correspond
(approximately) to on-screen signal levels. (One volt corresponds to the
top of the screen and zero volts corresponds to the bottom of the screen.)
This is true for both log and linear settings except when the spectrum
analyzer is in 1 dB/div or 2 dB/div. In these cases the log expand
amplifier is selected, and 1 V corresponds to top-screen and 0.8 or 0.9 V
corresponds to bottom-screen. The spectrum analyzer can be set to zero
span at the peak of a signal to generate a constant dc voltage in the
video circuits during sweeps.
1. Disconnect W26 from A3J101 and W20 from A2J4.
2. Connect W26 to A2J4.
3. Set the spectrum analyzer to the following settings:
Span ................................................................................. 0 Hz
Sweep time .................................................................... 20 ms
Resolution bandwidth ................................................. 1 MHz
Log/division ............................................................ 10 dB/DIV
4. If a trace is displayed, troubleshoot the A3 assembly. If a trace is
absent, connect an oscilloscope to the rear panel BLKG/GATE
OUTPUT.
5. The presence of a TTL signal (TTL low during 20 ms sweep)
indicates a good A3 Interface Assembly. Troubleshoot the IF section.
6. If the BLKG/GATE OUTPUT is always at a TTL high or low,
troubleshoot the trigger/video gating circuits on A3.
7. Reconnect W26 to A3J101 and W20 to A2J4.
8. Remove the A3 assembly shield.
9. If the video filters appear faulty, see to
10.If there appears to be a peak detector problem, refer to
“Positive/Negative Peak Detectors” on page 397
11.Connect the spectrum analyzer CAL OUTPUT to the INPUT 50
Ω
and set the controls as follows:
Center frequency ..................................................... 300 MHz
Span ................................................................................. 0 Hz
Reference level .........................................................
−
10 dBm
12.If the spectrum analyzer works correctly in 5 dB/div and 10 dB/div
but not in 1 dB/div or 2 dB/div, refer to
Continue with step 13 if the problem involves on-screen
amplitude errors which appear to originate in the video chain.
Содержание 8564EC
Страница 17: ...25 1 General Information ...
Страница 37: ...47 2 Adjustment Diagnostic Software ...
Страница 55: ...Chapter 2 65 Adjustment Diagnostic Software 2 LO Frequency Figure 2 2 LO Frequency Adjustment Locations ...
Страница 57: ...Chapter 2 67 Adjustment Diagnostic Software 3 YTO FM Coil Figure 2 3 YTO FM Coil Adjustment Locations ...
Страница 77: ...89 3 Manual Adjustment Procedures ...
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Страница 142: ...175 4 Assembly Replacement ...
Страница 151: ...184 Chapter4 Assembly Replacement Procedure 2 A1 Front Frame A18 LCD Figure 4 2 LCD Assembly Exploded View ...
Страница 163: ...Chapter 4 205 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 10 Assembly Cables 2 of 3 ...
Страница 166: ...208 Chapter4 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 14 GPIB and A1A1 W1 Cable Placement ...
Страница 168: ...210 Chapter4 Assembly Replacement Procedure 6 A6 Power Supply Assembly Figure 4 15 Power Supply Cover ...
Страница 176: ...226 Chapter4 Assembly Replacement A9 Input Attenuator Figure 4 22 A9 and A10 A12 Mounting Screws ...
Страница 179: ...Chapter 4 229 Assembly Replacement A11 YTO Figure 4 23 A11 Mounting Screws at Right Side Frame ...
Страница 183: ...Chapter 4 233 Assembly Replacement Procedure 8 A14 and A15 Assemblies Figure 4 25 A14 and A15 Assembly Cables ...
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Страница 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
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Страница 228: ...Chapter 6 307 Major Assembly and Cable Locations Introduction Figure 6 2 Top View A2 and A3 Unfolded ...
Страница 229: ...308 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 3 Top View A2 A3 A4 and A5 Unfolded ...
Страница 230: ...310 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 5 Bottom View A15 Unfolded ...
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Страница 234: ...315 7 General Troubleshooting ...
Страница 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Страница 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Страница 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Страница 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
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Страница 291: ...Chapter 8 381 ADC Interface Section Introduction Figure 8 2 A3 Test Connector Pin Locations ...
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Страница 322: ...427 9 IF Section ...
Страница 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
Страница 358: ...Chapter 9 463 IF Section A5 IF Assembly Figure 9 14 Noisy Signature Figure 9 15 Noise with Correct Shape ...
Страница 359: ...464 Chapter9 IF Section A5 IF Assembly Figure 9 16 Region B Amplitude Variation Figure 9 17 Region B Amplitude Offset ...
Страница 369: ...474 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 21 Output Waveform 10 kHz Resolution Bandwidth ...
Страница 370: ...Chapter 9 475 IF Section Cal Oscillator P O A4 Assembly Figure 9 22 Output Waveform 3 kHz Resolution Bandwidth ...
Страница 371: ...476 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 23 Output Waveform 1 kHz Resolution Bandwidth ...
Страница 372: ...Chapter 9 477 IF Section Cal Oscillator P O A4 Assembly Figure 9 24 Output Waveform 300 Hz Resolution Bandwidth ...
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Страница 394: ...521 11 Synthesizer Section ...
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