HP 70908A, Service Manual

Page: 79 / 335

If Y ou Have V erication T est F ailures
If T est 09. Image Rejection F ails
If any image rejection routines fail, the failure is most likely poor stopband response in one of
the lters in the signal path.
T o solve this problem:
1. Check for cracked solder joints on cables , loose connectors , and bad grounds (radiated).
2. Check the stop-band response of all the lters in the signal path.
3. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If T est 10. IF Rejection F ails
T o solve this problem:
1. Check signal rejection in the IF path until the faulty assembly is found.
2. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If T est 11. 2nd Converter Startup F ails
T o solve this problem:
1. If any 2nd converter startup verication routines fail, perform
A djustment 22. 2nd Converter Bandpass Filter Tune .
2. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If T est 12. IF Sub-Harmonics F ails
T o solve this problem:
1. Troubleshoot the A11 last converter 10.7 MHz trap (A11L10, A11C28) and 321.4 MHz
bandpass lter .
2. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If T est 13. Residual Responses F ails
If any residual responses routines fail, the failure is most likely caused by a harmonic of the 1st
LO mixing with a harmonic of the 3.3 GHz oscillator to produce a signal at an IF frequency .
T o solve this problem:
1. Check modules for cracked solder joints on cables , loose connectors , and loose screws
attaching printed-circuit boards and covers .
2. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
4-18 T roubleshooting