Agilent Technologies 8753ES Option 011 Service Manual page 276

Receiver Troubleshooting
Troubleshooting When One or More Inputs Look Good
Check the Trace with the Sampler Correction Constants Off
1. Press
Preset Meas
2. The trace is currently being displayed with the sampler correction constants on and
should resemble Figure
3. Press
SERVICE MENU
System
4. The trace is now being displayed with sampler correction constants off and should have
worsened to resemble
5. Press
SAMPLER COR ON
When the correction constants are switched off, an absolute offset and
NOTE
bandswitch points may be evident.
If the trace shows no improvement when the sampler correction constants are toggled from
off to on, perform "Sampler Magnitude and Phase Correction Constants (Test 53)" on
page 3-19. If the trace remains bad after this adjustment, the A10 assembly is defective.
Figure 8-7 Typical Trace with Sampler Correction On and Off
Check 1st LO Signal at Sampler/Mixer
If the 4 kHz signal is bad at the sampler/mixer assembly, check the 1st LO signal where it
enters the sampler/mixer assembly in question.
• If the 1st LO is faulty, check the 1st LO signal at its output connector on the A7
assembly to determine if the failure is in the cable or the assembly.
• If the 1st LO is good, continue with
8-12
A AUTO SCALE
Scale Ref
8-7a.
SERVICE MODES
Figure 8-7b.
. The trace should improve and resemble
"Check 2nd LO Signal at Sampler/Mixer,"
.
MORE SAMPLER COR OFF
Figure
.
8-7a again.
next.
Chapter 8