400
Chapter 8
ADC/Interface Section
A3 Assembly Video Circuits
3. Check A3U423 pin 4 for two low-going 3.3
µ
s pulses 40
µ
s apart
occurring every 130
µ
s.
4. Check that HROSENFELL (A3U610 pin 6) has two pulses spaced
approximately 40
µ
s apart and then a third pulse 60
µ
s from the
second pulse. Each pulse should be approximately 10
µ
s wide and
low-going.
5. Monitor HROSENFELL with an oscilloscope while reducing the
video bandwidth from 1 MHz to 1 kHz.
6. As the video bandwidth is decreased to 1 kHz, the HROSENFELL
line should increasingly show a low logic level. With a video
bandwidth of 1 kHz, a nearly flat line should be displayed on the
CRT.
7. Set the sweep time to 50 ms. Externally trigger the oscilloscope
using the spectrum analyzer rear panel BLKG/GATE OUTPUT.
8. Check that HPOS_HLDNG (A3U416 pin 4) is mostly high with a
1 MHz video bandwidth and mostly low with a 1 kHz video
bandwidth.
9. Check that LNEG_HLDNG (U408A pin 13) is mostly high with a
1 MHz video bandwidth and mostly low with a 1 kHz video
bandwidth.
ADC MUX
Refer to function block AA of A3 Interface Assembly Schematic
Diagram (sheet 6 of 6) in the 8560 E-Series Spectrum Analyzer
Component Level Information.
The ADC MUX switches various inputs into the video path for
conversion by the ADC. The SCAN RAMP input is used during sweeps
having a width of equal to or greater than 2.01 MHz times N, to control
the timing of the ADC operations. Some combination of MOD_VIDEO,
NEG_PEAK, and POS_PEAK is used for the video signal to be
converted by the ADC. The YTO ERR, FCMUX, CAL OSC TUNE, and
OFL ERR inputs are used only during diagnostic and auto adjust
routines and during retrace.
1. Set the spectrum analyzer to the following settings:
Center frequency .................................................. 300 MHz
Span .............................................................................. 0 Hz
Reference level .......................................................
−
10 dBm
Sweep time .................................................................... 50 s
DETECTOR MODE ............................................. SAMPLE
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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