888-2406-002
6-23
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
absorb the imbalance, increasing its temperature. The bigger the imbalance the
faster the temperature rises. Each resistor has a thermistor attached to it with a
special epoxy to sense the resistor temperature. When 150°C is exceeded (or
predicted to do so), the fault log will register a PA#_ISO fault (where # is a number
from 1-8), the transmitter will be muted for 120mS, the problem PA will be
switched out and the mute released.
This overload is actually a predicted overload based on the measured temperature
rise in the ISO load over a given amount of time. This means the ISO resistor will
not actually get to 150°C before the system trips, but that the system will switch out
the problem PA if that temperature would have occurred based on the ISO resistor
rate of temperature rise. To monitor the ISO resistor temperatures on the
Diagnostics Display press [METERING C,C]. This screen shows the ISO resistor
temperatures for PAs 1-4. Press [D] to see 5-8 and PAz.
NOTE:
The individual PA ISO resistor temperatures can vary quite a bit but
are to be considered okay if they are under A 75°C.
6.11.9 PA_ISO_OT
This is a general over-temperature fault which will shut the transmitter off if one of
the PA Isolation resistors in the combiner physically reaches 170°C (no prediction).
This protects against a failure in the combiner system where the Isolation resistor
does not get switched out of circuit. The primary cause would be a failure of the
Isolation Switch associated with the resistor.
However, a shorted thermistor (each PA isolation resistor has one attached to it for
temperature sensing) could also cause this fault since it will give what appears to be
a maximum temperature reading, greater than 170°C.
If this fault is triggered, all of the PA ISO temperatures should be checked. Since the
transmitter was shut off, they all should have cooled down. If one of them is still
extremely hot, above 150°C, then a thermistor (or the line to it) is probably shorted.
If all of the readings have cooled down then it is probably a failure of the RF
Switch. To locate the correct RF Switch and/or ISO Load get the PA#_ISO (there
should also be one of these in the Fault Log) fault number and use Table 4-1 to cross
reference.
6.11.10 PA_ISO_LOW, Fault
This fault will only show up if there is a problem found with the PA ISO resistor
during the System Test. During the System Test the PAs are muted one at a time.
This should cause the temperature of the ISO resistor to heat up. If it does not, then
the System Test is aborted and this fault is reported in the Fault Log. For more
information refer to “Self Diagnostics” earlier in this section.
Summary of Contents for Platinum Z2 CD
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Page 70: ...3 14 888 2406 002 WARNING Disconnect primary power prior to servicing Operator Guide ...
Page 130: ...4 60 888 2406 002 WARNING Disconnect primary power prior to servicing Overall System Theory ...
Page 194: ...6 38 888 2406 002 WARNING Disconnect primary power prior to servicing Troubleshooting ...
Page 196: ...7 2 888 2406 002 WARNING Disconnect primary power prior to servicing Parts List ...
