Ericsson EDACS Monogram Series, Руководство по обслуживанию

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AE/LZB119 1647 R1A
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Another function of the Display Board is to provide
backlighting of the LCD module using an electroluminescent
panel. The panel is controlled by the backlight line, a logic
switch output from the Audio Signal Processor (ASP) U804-
14. When this line is high Q101 is turned on. U107 and
C106 then have a path to ground. U107 is the High-Voltage
Lamp Driver which performs the function of DC to AC
conversion. The EL lamp driver frequency is determined by
R123.
PERSONALITY EEPROM U104
All personality data is stored in 4096 x 8-bit EEPROM
U104. This data, programmed with the PC programming
equipment, includes systems, groups, special cal l
information, frequencies, tones, option information, mic
deviation levels, data deviation levels, and squelch levels.
There is also a unique serial number stored in the EEPROM
that must match the serial number stored in the serial
number ROM U706. EEPROM U104 is programmed
through the same PC programming interface that programs
flash EEPROM U703. The micro controller serially
communicates with the EEPROM on the IIC CLK and IIC
DATA lines.
DTMF ENCODER U803
DTMF (Dual-Tone Multi-Frequency) tones are
generated by encoder U106. A 3.579545 MHz clock set by
crystal X101 runs only when a tone is being generated
during transmit keying. The encoders oscillator is disabled
by software to prevent harmonic and other spurious RF
signals from interfering with the receiver. When a software
command to generate a tone is sent to U106, the clock
oscillator recovers in less than 3 milliseconds.
The micro controller serially communicates with the
DTMF encoder on the IIC CLK and IIC DATA lines. The
DTMF tones at the output (U106 pin 5) are sent to the
receivers audio path in the ASP ( U804 pin 29) to provide
DTMF side tones. They are also sent to the TX audio path
via U804 pin 73.
MICROPHONE AND SPEAKER
The microphone mounts directly into the front panel.
The microphone receives acoustic power through a hole in
the front panel.
The speaker, mounted to the front panel, connects to the
Display Board through a 4 pin connector, J100. A
protective grill is placed in the front housing before the
speaker is mounted to screen out foreign material.
INTERNAL/EXTERNAL SPEAKER/MIC.
SWITCH
When the external Speaker/Mic. is used, the internal
speaker and microphone are turned off. When the external
Speaker/Mic. is connected to the radio through connector
J104 of the RF Board, pin 4 of J104 is connected to ground.
This will turn off Q102 and disconnect the internal speaker
and microphone.
DISASSEMBLY
FRONT PANEL ASSEMBLY REMOVAL
AND REPLACEMENT
To remove the front panel assembly:
1. Remove the battery by holding EDACS Monogram
radio in left hand, press the locking latch tab, push
battery out and away from transceiver.
2. Using a Phillips head screwdriver (No. 1) remove the
four (4) screws holding the bottom cover to front panel.
3. Remove the bottom cover.
4. Turn transceiver over where DTMF keypad is face-up.
5. Holding the frame firmly, place thumb of free hand
under the speaker grill near the (+) terminal. Lift the
front panel from chassis.
To replace the front panel assembly:
1. Ensure that all gaskets in position and not broken.
2. Place the lip at the top end of the panel assembly into
the gasket recess of front panel.
3. Press the front panel assembly firmly into position.
4. Place the bottom cover into position, and using a
Phillips head screwdriver (No. 1) tighten screws into
front panel assembly.