Adc Start/Stop Control - Agilent Technologies 8564EC Service Manual

ADC/Interface Section
A3 Assembly ADC Circuits
11.HBKT_PULSE is absent, refer to the information on troubleshooting
the frequency counter in
12.Reconnect A3W1 to A2J2.

ADC Start/Stop Control

Refer to function block B of A3 Interface Assembly Schematic Diagram
(sheet 2 of 6) in the 8560 E-Series Spectrum Analyzer Component Level
Information.
The ADC Start/Stop Control determines the start time of all ADC
conversions. Multiplexer A3U509 chooses the source of the start signal.
Both HSTART_SRC and HBUCKET tell the ASM to start a conversion.
1. Press on the spectrum analyzer and set the following
PRESET
controls:
Span .............................................................................. 0 Hz
Sweep time .................................................................... 60 s
Detector mode ....................................................... SAMPLE
2. Check for a TTL high at A3U509 pin 2 and a TTL low at A3U509 pin
14.
3. Set the detector mode to NORMAL.
4. Check that A3U509 pins 2 and 14 are both TTL low.
5. Set the spectrum analyzer to the following settings:
Span .......................................................................... 1 MHz
Detector mode ....................................................... SAMPLE
6. Check for a TTL high at A3U509 pin 2 and a TTL low at A3U509 pin
14.
7. Press and
CAL REALIGN LO &IF
pin 2 should be TTL low and pin 14 should be TTL high until the
10 kHz and narrower resolution bandwidths are adjusted. If correct,
the Start/Stop Control circuitry is being selected properly by the
processor and U508 in the ADC Register block is working properly.
8. Press on the spectrum analyzer and set the controls as
PRESET
follows:
Span .............................................................................. 0 Hz
Detector mode ....................................................... SAMPLE
Sweep time ............................................................... 400 ms
9. Check that A3U509 pin 7 has positive 15 µs pulses with a 667 µs
period (sweep time/600). Check that A3U509 pin 9 has positive 15 µs
pulses with a 667 µs period (sweep time/600). The pulses should be
present during the sweep but absent during retrace.
404
Chapter 10 , "Controller Section."
. During the realignment, A3U509
Chapter 8