296 Chapter6
General Troubleshooting
Using the TAM
Manual Probe Troubleshooting
Manual probe troubleshooting probes the instrument test connectors to
perform the following types of measurements:
• Amplifier and oscillator dc current draw by monitoring the voltage
across a resistor of known value.
• Oscillator tune voltages ensuring proper operation of
phase/frequency detectors and loop integrators.
• Static bias voltages.
NOTE Unlike E-series instruments, EC-series instruments do not have a TAM
connector on the A2 Controller board
If probing a connector for a check yields a "FAIL" indication, select the
desired check using either the knob or step keys and press
More Info. A
description of the function checked (with measured and expected
voltages/currents) is displayed with a list of additional areas to check.
These areas can sometimes be checked by looking at another TAM
connector, but usually require manual troubleshooting techniques to
isolate the problem further. If an HP-IB printer is connected, press
Print
Page to provide a hard copy of the currently displayed screen (the
softkey labels will not be printed).
Each test connector has fifteen pins (one pin is missing to act as a key).
The pins contain eight measured signal lines (measured signal lines
denoted as MS1 through MS8), one input signal line (OS1), one ground,
and five pins encoding a five-bit connector address.
The TAM needs to probe the revision connector of each assembly once;
subsequent readings are not necessary. It is possible, for example, to
probe the A5 IF assembly, then the A4 log amplifier assembly, and then
return to A5 without having to re-probe the A5 revision connector.
However, the revision connector must be re-probed if the spectrum
analyzer is returned to normal operation and then back to TAM control.
(This is also true if the spectrum analyzer is turned off.)
Cal Oscillator Troubleshooting Mode
The cal oscillator troubleshooting mode enables front-panel control of
the cal oscillator on the A4 assembly. The cal oscillator can be
fixed-tuned to three different frequencies. The cal oscillator may also be
set to one of four sweep widths, centered at 10.7 MHz.
Fixed-tuned settings:
11.5 MHz
10.7 MHz
9.9 MHz
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