Harris Platinum Z2 CD, Manual

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888-2406-002 6-13
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
used in the Vg (Gate Control Voltage for the individual PAs) menus and signifies
that there has been a crossover (this is a condition where one PA Controller crosses
over and mutes the PAs associated with another PA Controller).
6.9 Master Controller Faults
The following is a listing of the faults which are handled by or merely related to the
Master Controller. A quick reference for each of these faults is given in Table 6-1 at
the end of this section.
6.9.1 THERMISTOR, Fault
The Thermistor fault is detected if a thermistor temperature reading is 5° C below
the ambient temperature, provided the ambient temperature is above 25° C. Can be
caused by an actual open thermistor but is more likely an open connection between
the thermistor and the controller board monitoring the thermistor.
This fault protects against a thermistor (temperature sensor) circuit being open. The
thermistors are used on all amplifiers, iso loads, and the power supplies to sense
temperatures and use pull up resistors to +V. As the temperature increases, the
resistance of the thermistor goes down, lowering the voltage on a detector input,
which gives an increased temperature reading. If the thermistor circuit becomes
open, the detector input goes high which gives a cold temperature reading. This
leaves the device to which the thermistor is connected, unprotected from an over-
temperature condition. Once this fault is detected it will stay active in the log until
the Fault Log is reset.
NOTE:
If one of the thermistors or connecting cables is shorted, a tempera-
ture fault for the device it is connected to will be registered in the Fault
Log, not a THERMISTOR fault. A shorted thermistor or cable will give
a very hot reading which will not change, about 155° C or higher. If the
thermistor for one of the PA ISO resistors has shorted the PA_ISO_OT
fault is triggered and the transmitter will be shut off (see PA_ISO_OT
under PA Controller Faults).
6.9.2 EEPROM_DEF, EEPROM U39 Default Load
This fault means that when the controller loaded the transmitter settings from the
EEPROM U39 on the Master Controller, one or more of the values was considered
to be invalid or out of tolerance and was replaced with a Default value from the
firmware prom. This fault is an indication that the EEPROM U39 should be
replaced. (Refer to Section V, Maintenance and Alignments, for the replacement
procedure). The only time this fault should occur is when a new EEPROM U39 is
being installed. In this case it is random data and all defaults will be loaded
automatically. However, after the first default load it should never happen again.