Ericsson MDX SERIES, Service Manual, Page: 5 / 14

No RX Alert
Tone Check the signalling tone output from the
audio/logic board. Operate the volume
control. If tones are not present, the
audio/logic board may be faulty.
Poor RX Suspect the RF board. Check Sensitivity
and receiver alignment. Refer to the RF
board maintenance manual.
No TX Power Check the DPTT command to the RF
board. If present, then the problem is likely
on the RF board. If the DPTT is not present,
the problem is likely on the audio/logic
board.
Low TX Power Check the transmit frequency. If its not OK,
check the synthesizer on the RF board load
commands from the audio/logic board. If
the commands are not present, a problem
in the audio/logic board is likely.
If the TX frequency is correct, refer to the
maintenance manual for the RF board and
troubleshoot the transmitter.
No TX
Modulation Check the TX MOD input to the RF board.
If present, the RF board may be faulty. If
not present, determine what is missing:
tone, voice, or both.
Missing tones - Look for the signalling
tone and busy tone on the audio/logic
board. If the tones are not present, the
audio/logic board may be faulty.
Tones present - look for the proper unmute
commands on the audio/logic board. If the
commands are not present, the audio/logic
board may be faulty. If the commands are
present, the audio/amplifier board may be
faulty.
Missing Voice Signal - Check the mute
commands on the audio amplifier board
and the TX Audio input. If all signals are
correct, the problem is likely a faulty
audio/logic board. If no signal is present at
the audio/logic board, check the output
from the audio amplifier board and the
microphone outputs.
Radio will not
program when
plugged into
the TQ3310
or TQ3370 in-
terface module Verify radio is getting turned "on" by pro-
grammer.
Distorted TX
Audio Check grounding between all boards and
the casting.
Check the TX mod input to the RF board.
If distorted, a faulty audio/logic board is
likely.
Check the mute commands. If incorrect a
faulty audio/logic board is likely.
If the tones are distorted, check the tone
generation circuitry on the audio/logic
board.
Transmitter
Off Frequency Suspect the RF board. Refer to "Frequency
Set" procedure in the Transmitter Align-
ment section of this manual. Check the
synthesizer load command. If the load
command is wrong, a faulty audio/logic
board is likely.
Calls Processed
Incorrectly Check personality PROM programming.
Check for proper TX and RX operation.
Refer to TX and RX Verification Proce-
dures.
If verification OK, determine if the prob-
lem is in the transmit or receive circuit.
RX decode check: Use the decode T test
mode command. Modulate the generator
with the correct tone sequence and busy
tone. If the test fails, check the limited data
output from the audio/logic board. If the
data is not present, the audio/logic board
may be faulty.
TX encode check: Use the encode test. If
the test fails, the audio/logic board may be
faulty. Look for the proper tones on the
audio/logic board and proper unmute com-
mands. If all inputs are correct, the board
may be faulty.
TX/RX/Encode/Decode OK: Check proper
synthesizer switching time. Use BAND
SWT test. If the switching time is incorrect,
the RF board may be faulty.
TEST PREPARATION
Field test mode can be disabled via the PC programmer. If
enabled, the following describes the "User Testmode" that is
employed by the Dual Format MDX radio.
It is recommended that the users test frequency set include at
least 4 conventional channels with one of the channels being a
talk-around channel.
TEST MODE COMMANDS
At any time during the test if "TESTSET?" is displayed then
there is no Test Set programmed to perform the test. If "TONE-
SET?" is displayed then there is no GE-MARC tone set pro-
grammed to perform the test. At this point you will have to PC
program your radio with a Test/Tone Set to execute the desired
test. The suggested personality frequency test will contain at least
four frequency sets, preferably with one of the frequency sets
containing a talk-around frequency.
Test mode enables the technician to exercise test functions in
the field using the radios standard user interface (i.e. front cap
assembly). To enter the test mode the user must:
1) Press the SYSTEM and microphone PTT buttons while
powering up the radio.
2) When test mode is first entered "TESTMODE" appears in the
display. Once in test mode the user may step through the
various commands by pressing the Volume Up/Down but-
ton.
Once the desired test has been selected with the volume
buttons the MNU key must be pressed to activate the selected
test.
The selected commands are:
•
Default Set-up (DEFAULT)
•
Set Channel Test (SET CHAN)
• Volume Control (VOLUME)
•
Key/Unkey Transmitter (XMIT CON)
•
Mute/Unmute Receiver Audio (AUDIO CON)
• Mute/Unmute Mic Audio (PHON CON)
• Generate Dotting (4800 CPS)
•
Generate Pseudo Random HS Data (9600 PRD)
•
Encode Channel Guard Tone (150 CPS)
• Report Receiver Carrier Sense (CAS TEST)
• Across Band Switching (BAND SWT)
•
Generate Alert Tone (ALERT TN)
•
External RAM Test (RAM TEST)
• Software Version Number (UPR)
•
Checksum Test (PROG TS)
•
11 Hertz (11 HERTZ)
• TX Standard Busy Tone (TX BSYTN)
• Tone Set Select (TONE SEL)
•
DTMF Tone (TX DTMF)
• Decode Test (DECODE T)
• Encode Test (ENCODE T)
• Relay Switch (RELAY)
Key/Unkey Transmitter (XMIT CON)
Selecting the "XMIT CON" menu selection allows the user
to toggle the state of the transmitter; "XMIT ON" or "XMIT
OFF". Press the MNU button to display the last state of the
transmitter. Use the GROUP UP/DOWN buttons to toggle to the
desired state of the transmitter - on/off. Press the MNU button
to exit the transmit control mode, leaving the transmitter in the
last state selected.
Mute/Unmute Receiver Audio (AUDI CON)
The "AUDI CON" menu selection displays the state of the
audio; "AUDIO ON" or "AUDIO OFF". Press the MNU button
to display the last state of the audio. Use the GROUP UP/DOWN
button to toggle the audio on/off. Press the MNU button to exit
the audio control mode, leaving the audio in the last state se-
lected.
Mute/Umute Mic Audio (PHON CON)
Selecting the "PHONO CON" menu selection indicates the
current microphone audio state; "PHON ON" of "PHON OFF".
Press the MNU button to display the last state of the microphone
audio. Use the GROUP UP/DOWN button to toggle the micro-
phone on or off. Press the MNU button to exit the microphone
control mode, leaving the microphone in the last state selected.
Generate Dotting (4800 CPS)
This command causes the radio to begin generating a "dotting
"(i.e. "1010101010") pattern using its modem chip at 9600 baud
(4800 Hz signal). To modulate the transmitter with this pattern,
the transmitter must have been keyed using the "Key Transmit-
ter" command.
Select the "4800 CPS" menu selection. Press the MNU
button. The display flashes indicating the signal is being gener-
ated. The pattern will continue until another button is pressed.
LBI-38851 LBI-38851
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