888-2408-002
6-15
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
4.
System ISO Temp - ISO_AB. Located on the 3dB hybrid which com-
bines the Z-Planes. Is above the PA Modules under the rectangular
cover. The sense line (BNC coax) comes out the top of the box.
5.
Power Supply Temps - PS1 and PS2. These sensors are part of a screw
connector bolted to the top of the power supply heatsink (it is covered
with heat-shrink tubing).
b.
Once the problem thermistor is located, shut off the Low voltage supply with
CB1 in the rear of the transmitter. Use an ohmmeter to check the resistance of
the thermistor. It should be from 10K to 50K ohms depending on which ther-
mistor is being checked.
c.
If the thermistor is not open, turn the low voltage back on and check to see if
there is voltage across the thermistor. No voltage to the thermistor means an
open between the controller and the thermistor. Trace the connection back to
the controller board. Also, note that in this case the RFI boards have a series
inductor which may have opened.
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.
6.9.3
REF_WARNING, +5V Reference Warning
This is simply a warning that the +5Vdc reference voltage, used for system
software calibration, is less than 4.75Vdc. No transmitter action is taken other than
to report the fault in the fault log and light the Fault LED on the front panel. The
+5V Ref can be checked at TP4 on the Life Support Board where it originates. It is
adjusted with R28 also on the Life Support Board for +5.0Vdc.
6.9.4
MSTR_REF, +5V Reference Fault
This fault means that the +5V reference voltage, which comes from the Life Support
Board and is common to all of the controller boards, is less than 4.6V. This voltage
is used as the reference for all system calibration. A change in this voltage would
cause major errors in system calibration and overload settings and is therefore a
critical fault. The transmitter will be shut off. The +5V Ref can be checked at TP4
on the Life Support Board and adjusted with R28 also on the Life Support Board.
Summary of Contents for Z5 CD
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Page 192: ...6 40 888 2408 002 WARNING Disconnect primary power prior to servicing Troubleshooting...
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