Symptoms And Checks - Ericsson LBI-38953 Maintenance Manual

SYMPTOMS AND CHECKS

SYMPTOMS
Handset Blank On Power
Up
Radio Will Not Go Into
Test Mode Operation
Low, Distorted, or No RX
Audio
No RX Alert Tone
Poor RX Sensitivity
No TX Power
Low TX Power
No TX Modulation
Radio Will Not Program
When Plugged Into The
TQ3310 or TQ3370
Interface Module
Refer to the Power Distribution Block Diagram. Check for filtered A+ to the handset at J701-3,
8 volts at J702-6 or switched A+ at J905-5 (system board).
The radio must be PC programmed to enable the test mode. Enable it on the options screen.
Check the receiver VOL/SQ HI output. If distorted, the problem is most likely on the RF Board.
If synthesizer load commands are not correct, the problem may be on the Logic Board.
If the audio is correct at VOL/SQ HI, check the RX audio out. If improper, check the Audio
Board for proper unmute commands from the Logic Board. Proper commands indicate a faulty
Audio Board.
Check the signalling tone output from the Logic Board. Operate the volume control. If tones
are not present, the Logic board may be faulty.
Simplex operations: Suspect the RF Board. Check receiver alignment. Refer to the RF Board
maintenance manual.
Duplex Operation: If receiver OK, check lead placement on Duplexer/Talk-Around Board.
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 Logic Board.
Check the transmit frequency. If its not OK, check the synthesizer on the RF Board and the
synthesizer load commands from the Logic Board. If the commands are not present, a problem
on the Logic Board is likely.
If the TX frequency is correct, refer to the maintenance manual for the RF Board and
troubleshoot the transmitter.
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 Board. If the tones are
not present, the Logic Board may be faulty.
Tones present - look for the proper unmute commands on the Audio Board from the Logic
Board. If the commands are not present, the Logic Board may be faulty. If the commands are
present, the Audio Board may be faulty.
Missing Voice Signal - Check the mute commands on the Logic Board and the TX Audio input
to the Audio Board. If all signals are correct, the problem is likely a faulty Audio Board. If no
signal is present at the Audio Board, check the output from the Audio Amplifier board and
handset outputs.
The radio must be turned "on" before programming. Connect the handset and press the on/off
power switch.
CHECKS
LBI-38953
7