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LBI-38953
2. Place the "tinned" end of the component on the "tinned"
pad on the board and simultaneously touch the compo-
nent and the pad with a well "tinned" soldering iron
while pressing the component down on the board.
3. Place the "tinned" soldering iron on the other end of the
component and the pad simultaneously. Apply solder to
the top of the end of the component until the solder starts
to flow. Use as little solder as possible while making a
good connection.
4. After the component has cooled, use alcohol to remove
all flux from the component and printed wiring board.
TROUBLESHOOTING
PROCEDURES
The following information should help isolate a problem
to a particular board or circuit. Block diagrams for power
distribution and signal flow are provided at the end of this
service section. Refer to the appropriate instruction manual
for more details.
The MDR radio contains six functionalized boards or
assemblies. The major functions provided by each board are
listed below to aid in identifying the suspect board.
•
RF board
–
–
–
–
•
Duplexer
–
Interface or
Optional
–
Talk-Around
Board
–
•
Audio Board
–
–
–
6
Synthesizer: generates all trans-
mit and receive frequencies.
Receiver: provides detected
audio to the Audio Board.
Transmitter: includes exciter and
PA Module.
Power control circuitry: for trans-
mitter RF output power.
DC power Distribution
RF Power Sensing
The talk around option also in-
cludes the ability to switch the
transmitter output to the RX in-
put of the duplexer wen a talk-
around frequency is selected.
Analog to digital and digital to
analog conversion of the RX and
TX audio
CAS squelch output signal to the
Logic Board
Conventional analog tone filter-
ing and processing
•
Logic Board
–
–
–
–
–
–
–
–
–
–
–
•
System Board
–
–
•
Front Cap
–
Audio Assembly
SELF DIAGNOSTICS/ERROR MESSAGES
The radio performs several self diagnostic checks when
power is applied and informs the user of a possible problem
within the radio. These tests provide the following error
messages on the display:
•
PC PROG
–
•
ERROR 2
–
•
UNLOCK
–
•
–
PROM BAD
Routes signals between the RF,
Audio, And Control Boards
Contains the EEPROM for the ra-
dio personality
Contains the main radio micro-
processor
Accepts PTT from the micro-
phone
Provides DPTT to turn on the
transmitter
Provides synthesizer channel data
to the RF board
Processes RX and TX audio using
an digital signal processor.
Decodes tone data from the Audio
Board.
Generates the Channel Guard
tones and data.
Controls all audio switches on the
Audio Board.
Accepts the CAS squelch output
from the AudioBoard.
A+ switching circuitry
Option connections
Contains the Audio Amplifier
Board and 10 watt Amplifier.
No personality. The radio has not
been programmed with custoer
information.
occurs when the synthesizer is
unable to lock on frequency.
S ynt he s i z er unl o ck ed. The
syunthesizer is tested to verify
that it will lock in the proper
amount of time at various fre-
quencies across the band.
EPROM program memory check-
sum error. If rhe microprocessor
us e s e xt e rna l m em ory, t he
EPROM has been corrupted or is
malfunctioning.
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