User's Manual

Chapter 5 Troubleshooting
Troubleshooting
This section offers brief suggestions to try in the event that the MMI is not functioning
properly. The only items covered in this section are those which are user serviceable, or
those which the operator is responsible for properly setting up or checking during
operation.
•
••
• Handheld terminal does not turn on, or does not respond.
First verify that there are no illuminated and non-flashing red LED’s on any of the
main computer boards at the upper left of the MMI. If nothing seen, then
inspect that the main power cable is correctly connected. If there no obvious
cabling problems, then the two internal fuses should be checked.
These may be found just inside the rear cover door of the MMI which is opened
by removing three small screws. There is a separate fuse holder for the external
power connection as well as for the internal battery. These fuses are standard
automotive types. Replace with a 20-amp fuse.
•
••
• Poor reading performance or range.
This should be verified by using the Troubleshoot menu contained within the
Tools
command. Using a known good transponder, if it is verified that the transponder
is
difficult to communicate with, then check both antennas. The whip section of
each
antenna should be screwed down tightly to the base, and the transmit antenna
must be screwed on the MMI connector until tight. Also verify that all the
green PLL OK LED’s are illuminated on the transmitter and receiver boards.
Also verify that both RF amplifier LED’s are illuminated.
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••
• Uninitialized transponders are not read in GEO mode.
Using the System Setup menu contained within the Tools command, verify that
the minimum GEO mode signal strength requirement is not set too high. As a
check, this value may be set to 0 to disable the requirement.
•
••
• Transponders are able to be read in FIFO mode, but not in L/L mode.
Verify that the GPS has an active status. If so, then turn off the dynamic window
feature, then check the interrogation window size using the System Setup menu in
the Tools command. As a check, this value may be set to 20 to use a 2000-foot
window radius. If this still fails to produce readings in L/L mode, then verify that
the MMI considers the transpoders in question to be within range by using the
UNRD summary menu. This will display the distance between each unread
transponder and the MMI. If the displayed distance is not what is expected, then
the Lat/Lon coordinates for the transponders in question may be unitialized, or
invalid.