Agilent Technologies 856290216 service manual ADC Start/Stop Control

ADC Start/Stop Control

Refer to function block B of A3 Interface Assembly Schematic Diagram in the

HP 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 (PRESET) on the spectrum analyzer and set the following controls:

Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lMHz Detector mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAMPLE

6.Check for a TTL high at A3U509 pin 2 and a TTL low at A3U509 pin 14.

7.Press (CAL) and RF&J&N LO & IF. During the realignment, A3U509 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 (PRESET) on the spectrum analyzer and set the controls as follows:

Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Detector mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAMPLE Sweep time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400ms

9.Check that A3U509 pin 7 has positive 15 ps pulses with a 667 ps period (sweep time/600). Check that A3U509 pin 9 has positive 15 ps pulses with a 667 ps period (sweep time/600). The pu1 ses should be present during the sweep but absent during retrace.

10.Set the detector mode to NORMAL.

11.Check that A3U509 pin 9 has pulses every 130 ps and U509 pin 7 has pulses every 667 ps (although pulse widths may be changing).

ADC/lnterface Section 8-25