888-2406-002 6-11
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
d. The thermistor has come loose from the resistor. Each thermistor is attached
to the resistor which a high temp epoxy. If this has come loose the thermistor
would not heat up as it should. With the transmitter on and operating nor-
mally, check the ISO temperature of the PA reported as bad and see if it is
approximately the same as the others on that Z-Plane.
6.7.1.3 PA RF Switch Test
If it passes the previous tests, then the PA rf switches will be energized one at a
time. If it works as it should, the ISO resistor will not rise in temperature within a 2-
20 second window. At the same time the controller is also checking to see how
much the system dropped in output power to make sure the combiner is configured
properly and that the PA was working in the first place. If either part of the test
indicates a problem, it will also report a B#_ISO_SW Fault to the Fault Log and will
abort the test.
6.7.2 Hardware Test
The other option in Figure 6-4 is to test the hardware. Pressing [D] should bring up
the screen in Figure 6-6. This screen gives 3 more choices:
Figure 6-6 Hardware Test Menu
a. LCD/LED Test - This is a test of all of the LCD segments and LEDs on the
front panel to make sure the overlay indicators are operational. Pressing [B]
will active the test. Press [B] again to shut off the test.
b. EEPROM TEST - This will test EEPROM U39 on the Master Controller (the
only socketed IC on the board). This is where all of the user data and the Fac-
tory Default Settings are stored. This test should only be done if there is a
problem recalling the Factory Default Settings in the Diagnostics Display or
if the Master Controller needs to be replaced. If it fails the test, U39 will have
to be replaced and a complete “System Configuration and Calibration” will
have to be done per the procedure in Section V.
c. Main DAC Test - This test should only be done as a last resort in a case where
the system control appears erratic. To run the test requires an oscilloscope. It
is a test of the main Digital-To-Analog-Converter on the Master Controller
Board. To run the test shut the transmitter off and press [MORE, TEST, D,D].
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