______________________________________________
HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
189
Enable switch S1 allows local control of the module on the extender while the
transmitter is on.
CAUTION:
AN EXTERNAL RF LOAD MUST BE CONNECTED TO THE MODULE AT ALL
TIMES DURING TEST. BE SURE TO DISABLE AND REMOVE THE MODULE
OR TURN OFF THE BREAKER BEFORE REMOVING THE EXTENDER FROM
THE CABINET.
8.3.2 Troubleshooting Based on Module Swapping
Many situations exist in which a problem exhibited by a module could be due to a
problem either with the module itself, or somewhere else in the transmitter. For
example, VSWR faults could be due to either a failure or mis-adjustment of the VSWR
sensing circuitry in the module, or due to a problem with the transmitter cabinet RF
connector, combiner cables, reject loads, etc. In fact, most fault indications could be
caused by either module or system problems. Thus it is desirable to first isolate the
problem to the module or system before continuing the troubleshooting process.
Since the modules are designed for interchangeability with other modules of the same
type, one easy test to determine whether a problem lies in the system or in the module is
the "swap test," which involves swapping the suspect module with another and
observing whether the symptom follows the module.
8.3.3 Troubleshooting Based on Module Blink Codes
The general procedure for troubleshooting based on a module blink code involves
several steps.
The first is to check for causes consistent with the blink code (such as checking the DC
supply voltage if blink code 4 occurs). Often, this will give an indication of whether the
problem lies within the system or the module.
If this does not locate the problem, then the next step is to check for correct threshold
voltages on the module logic board. Fault blink codes result from a sample voltage
taken within the module exceeding some preset threshold. Thus, if no other module or
system problem is found, the problem may be due to an incorrectly set fault threshold
(as in the case of thresholds set with potentiometers), or a defective component (such as a
resistor) used to establish a threshold. The theory of operation of the module Protection,
Control and Monitor subsystem, gives detailed descriptions of how these thresholds are
derived and compared against the corresponding voltage samples.