HP 8560A Service Manual page 390

7. If a correct signal is seen at A15TP201 but the signal at A15TPlOl is wrong, proceed as
follows:
Use an oscilloscope to measure the signals at the following test points:
.
If these levels are wrong, perform the "Power and Sampler Match Adjustments" in the
Sampler Oscillator Adjustment procedure. Refer to Chapter 2.
If adjusting the Sampler Match does not bring the signal at Al5TPlOl within
specification when the signal at A15TP201 is correct, the A15A2 Sampler is defective.
8. If the signal at A15TPlOl is correct, but the signal at A15JlOl is wrong, the fault lies in
the Sampler IF circuitry. Continue with the following steps.
9. Set the HP 8560A to the following settings:
C E N T E R F R E Q
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz
10. Set a microwave source to the following settings:
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2107GHz
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -5 dBm
11. Connect the microwave source to A15A2Jl.
12. Measure the signal at U103 pin 1 using an active probe/spectrum analyzer combination.
13. If a 94.7 MHz signal, approximately -14 dBm, is present, but the signal at A15JlOl is
low, suspect U103.
14. When U104 pin 3 is at TTL low, U104 pin 6 should near -15 Vdc and PIN diodes
15. Set HP 8560A to the following settings:
C E N T E R F R E Q
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz
16. Check that U104 pin 3 is at a TTL high and U104 pin 6 is greater than +7 V. PIN diodes
17. Disconnect the power splitter and reconnect W32 to A15JlOl.
-1.8 Vdc to -2.4 Vdc (SO.5 Vp-p variation)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..300MHz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.3MHz