TM840 Service Manual
Chapter 9. Common Fault Phenomenon and Elimination Method
No
Problem
Causes and Solutions
1
The radio cannot be powered on.
A
.
The power ON/OFF key may suffer from poor contact. Clear the metal dome with alcohol and try again.
B The connecting between power cable and power supply is not good enough.
C
.
The power is connected inversely which leads to the power protective tube open. Replace the protective tube and try
again.
2
You cannot communicate with other
members
A
.
The frequency settings may be different from others. Set your TX/RX frequencies to be the same as others.
B
.
The CTCSS/CDCSS signaling may be different from others. Set your CTCSS/CDCSS signaling to be the same as
others.
C
.
Your place may be too far away from the others, beyond the radio’s coverage area.
3
The radio cannot receive signals
A
.
Check whether the antenna is connected well with radio, please reinstall it again.
B
.
Check whether the tx and rx is set right.
C. You place may be too far away from the others, beyong the radio’s overage area.
4
During receiving, LED is green but no
voice.
A
.
Check whether the volume is smallest or not. If so, increase the volume.
B
.
Check whether the speaker is broken or not. If so, change the speaker.
5
GPS cannot locate your position.
A. Check whether the antenna is dual band or not. If not, use a dual band antenna to replace the old one.
B. Check whether the GPS setting is correct or not. If not, set it correctly.
C. Maybe there is some other RF interference around the radio’s place. Go to an open sky place and try again.
6
Programming failed.
A
.
Connection between the radio and PC is not good enough. Check and try again.
B
.
Programming interface has poor contact with external programming cable. If so, change the programming interface
on mobile..
12.16 Ω dummy load
16Ω
,
3W
13.Power supply output
Output: 5Vto 30V
,
Current
:
20A
37
Summary of Contents for TM840
Page 1: ...TM840 Service Manual I ...
Page 19: ...TM840 Service Manual Figure4 3 4 Click Next to keep on installation 16 ...
Page 60: ...TM840 Service Manual Figure1 TM840 400 470MHz Mainboard Top Side PCB View 57 ...
Page 61: ...TM840 Service Manual Figure2 TM840 400 470MHz Mainboard Bottom Side PCB View 58 ...
Page 62: ...TM840 Service Manual Figure3 TM840 400 470MHz Keypad Board Bottom Side PCB View 59 ...
Page 63: ...TM840 Service Manual Figure4 TM840 400 470MHz Keypad Board Top Side PCB View 60 ...
Page 82: ...TM840 Service Manual Figure7 TM840 136 174MHz Mainboard Top Side PCB View 79 ...
Page 83: ...TM840 Service Manual Figure8 TM840 136 174MHz Main Board Bottom Side PCB View 80 ...
Page 84: ...TM840 Service Manual Figure9 TM840 136 174MHz Keypad Board Bottom Side PCB View 81 ...
Page 85: ...TM840 Service Manual Figure10 TM840 136 174MHz Keypad Board Top Side PCB View 82 ...