Agilent Technologies 856290216 service manual RF Section

a. Set the spectrum analyzer (LINE) switch OFF, disconnect W13 from A14J12, and set the luNE) switch ON.

b. Wait for the power-on sequence to finish and then set the spectrum analyzer settings to the following:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...3 GHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz

c. If the DVM measures -15 Vdc ho.2 V, the Al3 second converter is probably defective. If the DVM measures outside this limit, the Al4 frequency control assembly is probably defective.

9.Set the luNE) switch OFF and reconnect W13 to A14J12.

10.Remove the test cable from A13J2 and reconnect W35 to A13J2.

11.Disconnect W33 (coax 81) from A13J4 and connect W33 through a test cable to the input of another spectrum analyzer.

12.Tune the other spectrum analyzer to a center frequency of 600 MHz.

13.If a 600 MHz signal is not present, or its amplitude is less than -5 dBm, the fault is probably on the Al5 RF assembly.

14.Reconnect W33 to A13J4.

15.Connect the positive lead of a DVM to A14J19 pin 15 and the negative lead to A14J19 pin 6.

16.If the DVM does not measure between t14.0 Vdc and i-15.0 Vdc, perform the following:

a.Press [LINE) to turn spectrum analyzer off and disconnect W13 from A14J12.

b.Press m to turn spectrum analyzer on and set the spectrum analyzer to the

following settings:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..300MHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lO MHz

c. The voltage should measure +15 Vdc f0.2 V. If the voltage measures outside this limit, the Al4 frequency control assembly is probably defective.

d. Press (LINE to turn spectrum analyzer off. Reconnect W13 to A14J12, and press (LINE) to turn spectrum analyzer on. Set the HP 85623 to the following settings:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..300MH~ Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz

17.Move the positive lead of a DVM to A14J19 pin 1. The voltage should measure between -150 mVdc and -800 mVdc. If the voltage measures outside this limit, the Al3 Second Converter is probably defective.

12-10 RF Section