412 Chapter8
IF Section
Troubleshooting Using the TAM
Figure 8-2 IF Section Troubleshooting with the TAM
Both the digital control and DACs are multiplexed onto test point
"channels" through resistive networks. One DAC from each of the
quad-DAC packages feeds into a network. The TAM varies each DAC
individually to isolate which ones failed. Similarly, 10
digitally-controlled lines feed into a network and are monitored by the
TAM. The channels used to monitor the DACs are listed below:
1. On the HP 8560E/EC, press
PRESET, MODULE, and Diagnose. Select
Cal Osc Troubleshooting Mode.
2. On the HP 8560E/EC, disconnect W27 (coax 3) from A5J5 and
monitor the output of A5J5 with a second spectrum analyzer.
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