Front End Assembly Control Logic Verification - Keysight n9020a Service Manual

Front End Control Troubleshooting
A15 Front End Control Assembly Troubleshooting
If any of the preselector control currents do not match the levels shown in
Figure
End Control Assembly. Perform the YTF characterization (press System,
Alignments, More, Ad vanced, Characterize Preselector) and re-check the
control current at various center frequencies.
Table 5-9 YTF Tune Current
Center Frequency
(GHz)
5.0
10
15
20
26
Tolerances should be used as a guideline. The true test is whether or not the
NOTE
analyzer will function and meet published specification.

Front End Assembly Control Logic Verification

Since the RF Front End Troubleshooting board is connected, now is a good
time to test out the remaining control circuits from the A15 Front End Control
Assembly.
Table 5-10 Front End Control Logic
Test Point Description
S2A Sets switch for Low Band/preamp path
S2B Sets switch for Low Band/preamp path
S3A Sets E-atten to 5 dB preamps off
S3B Sets E-atten to 5 dB preamps off
S4A Sets E-atten to 10 dB preamps off
S4B Sets E-atten to 10 dB preamps off
S5A Sets E-atten to 2 dB preamps off
5-9, the most probable causes are a misaligned YTF or the A15 Front
Control Current
(ma)
106
215
324
430
560
219
Tolerance
(ma)
± 20
± 25
± 30
± 40
± 50
Instrument Vol tage
Settings (VDC)
CF 50 MHz preamp +9.67
on
CF 50 MHz preamp +9.83
on
E-atten = 5 dB +9.67
E-atten = 5 dB +9.83
E-atten = 10 dB +9.67
E-atten = 10 dB +9.83
E-atten = 2 dB +9.67
Tolerance
(VDC)
±0.5
±0.5
±0.5
±0.5
±0.5
±0.5
±0.5