Video Filter Buffer Amplifier - Agilent Technologies 8564EC Service Manual

ADC/Interface Section
A3 Assembly Video Circuits
6. If the output of latch A3U102 is not correct, trigger an oscilloscope
7. If the inputs are incorrect, troubleshoot the analog bus. Correct
8. Check that the outputs of A3U111A, A3U111B, and A3U107A/B/C/D
9. To return the spectrum analyzer to automatic sweep, press
Table 8-6 A3U102 Latch Outputs
Video BW
300 Hz
1 kHz
3 kHz
10 kHz
30 kHz
100 kHz
300 kHz
1 MHz
3 MHz
Video Filter Buffer Amplifier
Refer to function block W of A3 Interface Assembly Schematic Diagram
(sheet 5 of 6) in the
Informatio
The video filter buffer amplifier provides outputs for video trigger,
positive and negative peak detectors, and the analog zero-span (sweeps
<30 ms). The zero-span video output is terminated in 500 ohms on the
A2 Controller assembly. The amplifier is a high-input-impedance buffer
amplifier with a gain of one when properly terminated.
396
on LLOG_STB (U102 pin 9) and monitor U102 pin 1 and other latch
inputs while changing the video bandwidth.
inputs with bad outputs indicate a faulty U102.
are correct for their inputs. The outputs should be high with
noninverting inputs higher than the +1.4 V threshold voltage. If a
voltage drop is noticed across these components, suspect A3CR109 or
A3Q317B. Since no dc current flows through any of the series
resistances or FETS (drain to source), no voltage drops should occur.
,
SWEEP SWEEP CONT SGL
Pin 2 Pin 5
H L
L L
L H
L L
H L
L L
L H
L L
L L
8560 E-Series Spectrum Analyzer Component Level
n.
or .
PRESET
Pin 7 Pin 10 Pin 12
L L L
L L L
L L L
L L H
H L L
H L L
H L L
H L H
L H L
Pin 15
L
H
L
L
L
H
L
L
L
Chapter 8