374
Chapter 9
Assembly Descriptions and Block Diagrams
IF Section
A12 Amplitude Control
The A12 amplitude control assembly provides gain or attenuation in
eight stages: three step-gain amplifiers and five step attenuators. All
stages, except the 10 dB step gain, provide full gain or attenuation
when turned on and unity gain when turned off. The 10 dB step gain
has a gain of 15 dB when on and a gain of 5 dB when off.
When the reference level is changed, the A7 analog interface assembly
interprets the A16 processor/video assembly commands and produces
the appropriate combination of gain and attenuation control voltages in
1 dB increments. Reference-level resolution of less than 1 dB is
produced by mathematically offsetting the digitized video signal on the
A16 processor/video assembly.
A12 step-gain errors are corrected by correction factors produced by the
CAL AMPTD
self-calibration routine. Each correction factor is an offset
of the digitized video signal and is stored in nonvolatile memory on the
A16 assembly.
A12 step-attenuator errors are corrected by correction constants that
are characterized values initially installed at the factory. The corrected
calibration attenuators provide the amplitude reference used by
CAL
AMPTD
self-calibration routine.
A13 Bandwidth Filter
The A13 bandwidth filter assembly is identical to the A11 assembly.
Refer to the A11 assembly description in this section.
After leaving the A13 assembly, the 21.4 MHz IF signal branches on the
A15 motherboard:
• One branch passes directly to the A14 log amplifier assembly.
• A buffer amplifier on the A15 motherboard attenuates the IF signal
by 20 dB and distributes it to the card-cage assemblies (AUX_IF),
the rear panel AUX IF OUTPUT connector (AUX_IF_BP), and the
A25 counterlock assembly (COUNT_IF). The COUNT_IF signal is
used by the A25 assembly to count the actual IF frequency when
MKR CNT ON
is selected.
• Another buffer amplifier on the A15 assembly sends the IF signal
(AUX_IF) to assemblies installed in the card cage.
Summary of Contents for 8590L
Page 29: ...30 Chapter1 Introduction If You Replace or Repair an Assembly ...
Page 175: ...176 Chapter2 Making Adjustments 28 Correcting for Absolute Amplitude Accuracy for Option 051 ...
Page 279: ...280 Chapter5 Troubleshooting the IF Section Troubleshooting the A15 Motherboard Assembly ...
Page 347: ...348 Chapter7 Replacing Major Assemblies Rear Frame Assembly ...
Page 355: ...356 Chapter8 If You Have A Problem Returning Your Analyzer for Service ...
Page 379: ...380 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 380: ......
Page 381: ...382 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 382: ......
Page 383: ...384 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 384: ......
Page 385: ...386 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 386: ......
Page 387: ...388 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 388: ......
Page 389: ...390 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 390: ......
Page 391: ...392 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
Page 392: ...393 10 Analyzer Options and Block Diagrams ...
Page 443: ...444 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 444: ......
Page 445: ...446 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 446: ......
Page 447: ...448 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 448: ......
Page 449: ...450 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 451: ...452 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 483: ...484 Chapter11 Major Assembly and Cable Locations Major Assembly and Cable Locations ...
Page 537: ...538 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 538: ......
Page 539: ...540 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 540: ......
Page 541: ...542 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 542: ...FOLDOUT 12 3 8590L AND 8591E RF ASSEMBLY ...
Page 543: ...544 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 544: ......
Page 545: ...546 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 546: ......
Page 547: ...548 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 548: ......
Page 549: ...550 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 550: ......
Page 551: ...552 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 665: ...666 Chapter15 Service Equipment and Tools Service Equipment and Tools ...
Page 666: ...667 16 Safety and Regulatory Information ...
Page 673: ...674 Chapter16 Safety and Regulatory Information Protection from Electrostatic Discharge ...