Agilent Technologies 856290216 service manual A3 Assembly Control Circuits, Analog Bus Drivers

A3 Assembly Control Circuits

A digital control problem will cause the following three steps to fail.

1.On the spectrum analyzer, press (i$Kii%Z), ATTEN MAN, 7, 0, and (dB.

2.A click should be heard after pressing dB in step 1, unless ATTEN was previously set to 70 dB.

3.Press 1, 0, and (dB. Another click should be heard. If no clicks were heard, but the ATTEN value displayed on the CRT changed, the digital control signals are not operating properly.

Analog Bus Drivers

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

HP 8560 E-Series Spectrum Analyzer Component Level Information.

1. Press (“1 on the spectrum analyzer, and set the controls as follows:

Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single

2.Monitor A3U401 pin 3 (LRF-STB) with an oscilloscope or logic probe. This is the strobe for the Al5 RF Assembly.

3.Press (mCTRL) and REAR PANEL and check that pulses occur when toggling between

10 MHz 1NT and 10 MHz EXT.

4.Monitor U401 pin 5 (LFCSTB) with an oscilloscope or logic probe. This is the strobe for the Al4 frequency control assembly.

5.Press (AMPLITUDE) and check that pulses occur when toggling between ATTEN settings of 10 and 20 dB.

6.Monitor U401 pin 7 (LIF-STB) with an oscilloscope or logic probe. This is the strobe for the A5 IF assembly.

7.Press (-1 and check that pulses occur when toggling between REF LVL settings of -10 dBm and -20 dBm.

8.Monitor U401 pin 9 (LLOG-STB) with an oscilloscope or logic probe. This is the strobe for the log amplifier on the A4 assembly.

9.Press (-1 and check that pulses occur when toggling between LTNEAE and

Lac ~B/~)IV.

10.To check the Address and Data Lines, place a jumper from A3TPl and A3TP2 to A3U406 pin 20 (+5 V).

11.Check that address lines A0 through A7 and data lines DO through D7 are all TTL high.

12.If any address or data line is low, press (LINE) to turn spectrum analyzer off and disconnect the W2 control cable from A3J2. Press (LINE) to turn spectrum analyzer on. Ignore any error messages.

8-28 ADC/lnterface Section