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A. Display Messages
Failure messages, "FL XX/XX," or error messages,
"ER XX/XX," are related to radio command board prob-
lems in all cases except the following:
•
FL 05/81 - control head microprocessor ROM
error; replace control head board.
•
FL 05/88 - control head microprocessor RAM
error; replace control head board.
•
FL 01/90 - serial data bus failure; may be either
a control head failure, a cabling failure, or a
radio command board failure.
B. Control Head Problems
The following symptoms are caused by a control
head problem:
•
Flickering "SELF CHK" but no failure message.
•
Control head powers up; however, button
presses have no apparent effect.
•
A few segments (or characters) will not light on
display.
•
Very bright display; varies with supply voltage.
•
Very dim display.
If the display does not function, or if button presses
have no effect, remove the control head and perform the
control head test (see paragraph X.). If this fails to pro-
duce the desired results, remove the control head board
and install a new board. If it passes the test, check for
cabling or command board problems.
36
III. TRANSMITTER TROUBLESHOOTING
When setting or measuring RF power at 900 MHz,
you must follow these guidelines to avoid measurement
errors due to cable losses or non-50-ohm connector
VSWR:
1. All cables should be very short and have Teflon
dielectric.
2. Attenuators and 50-ohm loads should have at least
25 dB return loss.
3. Mini UHF-to-N adaptor 58-80367B21 can be used
at the antenna connector. All other connectors
should be "N" type. No other adapters, barrel con-
nectors, etc., should be used.
Figure 13 shows the preferred test set-up using no
cables.
Table 12 lists a number of transmitter-related symp-
toms which may occur that interrupt normal radio
operation. Use this chart to help troubleshoot and repair
transmitter problems to the board level. This chart does
not attempt to isolate problems to the component level.
INSERT GPW-4743-A
R.T. 60% PICKUP FROM PG. 33
Figure 13.
Transmitter Troubleshooting Preferred Test Setup
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Troubleshooting
