2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
93
3.2.2.1 A9J3 80-MHz Signal Cable Test
1 Disconnect cable from A9J3.
2 Connect A9J3 to the 50 input of an oscilloscope. (If a 50 input is absent,
use the high-impedance input with a 50 coaxial-feedthrough terminator at
the scope end of the coax).
3 Verify presence of an 80-MHz undistorted sine wave with at least
0.6 Vp-p amplitude.
4 Reconnect cable to A9J3.
QUESTION: Does the scope show an 80-MHz undistorted sine wave
with at least 0.6 Vp-p amplitude?
If Yes: Remove power, replace cable between A9J3 and A5J1,
and retest.
If No: Go to, 3.4.1.0 (A9 diagnostic tree).
3.2.3.0 A4 131.770-kHz Signal Test
1 Disconnect coax cable from A5J2.
2 Connect free end of the cable to an HP/Agilent 8566 spectrum analyzer (or
equivalent).
3 Set the center frequency to 131.7 kHz. and the span to 10 kHz.
4 Verify presence of a signal at 131.770 kHz with at least -15 dBm amplitude.
5 Reconnect cable to A5J2.
QUESTION: Does the spectrum analyzer show a signal at
the correct frequency and amplitude?
If Yes: Go to, 3.2.4.0.
If No: Remove power, replace A4, and retest.
3.2.4.0 A5 Mon Signal Test
1 Measure dc voltage on the mon terminal with a scope.
2 Verify that the voltage is less than +0.25 Vdc, greater than -0.25 Vdc, and
contains negligible (<10 mV.) ac content?
QUESTION: Does the mon terminal signal meet the above
signal specifications?
If Yes: Go to, 3.2.5.0.
If No: Remove power, replace A5, and retest.
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