Controller Troubleshooting (Sheet 1) - Motorola MTM800 User Manual

9.1 - 4

Controller Troubleshooting (Sheet 1)

Failure:
No "Radio HW is READY" message on Tetra Com screen 10 sec after
the supply voltage has been applied.
Communication with PATS failed.
Send Tetra Com command "MODE" several times for the followings
test and measure the test point signals with a scope.
Start
Disassemble main board from radio chassis.
Check main board visually.
Check fuses F0301and F0302 on the main board.
Data
activity on
TP0404, TP0405
and TP0401
?
Yes
Yes
Data
activity on
TP0402
?
No
Measure the DC voltages of the
1.8V, 1,55V and 3V regulators.
No
1.55V DC at
U0306 pin 1
?
Yes
No
3V DC at
U0305 pin 1
?
No
1.8V DC at
U1105 pin 5
?
Yes
No
3V DC at
U0305 pin 5
?
Yes
A
Successively replace:
Q0342, U0308, U0304, U0305, U0306
See Sheet 2
No
Check components and
connections between TP's and
accessory connector.
Check components and
connections between TP
and accessory connector.
Yes
5V DC at
U0303 Pin 3
?
No
Before replacing U0305 check for
5V DC at pin 8 and check
associated components.
Replace U1105
No
5V DC at
U0304 pin 1
Go to DC supply chart.
(TP0301)
?
Yes
No
3V DC at
Check for cold solder
U0308 pin 2
?
Yes
TROUBLESHOOTING CHARTS: 450-470MHz
Before replacing U0306 check
for 5V DC at pin 8 and check
associated components.
Digital DC supply failure!
Go to DC Supply Chart.