HP 8560A manual 289

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Figure 8-2. IF Section Troubleshooting with 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:

Channel A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5J9 pin 1 (MSl) ChannelB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..A5Jgpin 3(MS3) Channel C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5J9 pin 4 (MS4) Channel D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A5J9 pin 2 (MS2)

1.On the spectrum analyzer, enter the TAM Cal Osc Troubleshooting Mode by selecting diagnose then Cal Osc Troubleshooting Mode.

2.On the spectrum analyzer, disconnect W27 ( coax 3) from A5J5 and monitor the output of A5J5 with a second spectrum analyzer.

IF Section 8-7