Motorola MTM800 - Receiver Troubleshooting (Sheet 1)

9.1 - 14 TROUBLESHOOTING CHARTS: 450-470MHz
Receiver Troubleshooting (Sheet 1)
No VCO output signal!
Go to Main VCO Chart
0V DC at U5701
pin 19 & 20
?
RF level at
C5704 about -5dBm
?
RF level at
TP5702 about
-5dBm
?
RF
level at
TP5071 about
10dBm and frequency
stable at
331.675MHz
?
RF
level at
TP5071 about 10dBm
but frequency
incorrect
FGU failure!
Go to Main Synthesizer Chart
Set IFR TX Frequency to 405.025MHz
Set IFR Reference Level to 0dBm
Check transitor
stage Q5701,
switch Q5711 and
switch Q5301
Check switch Q5301
and components
between Q5301 and
U5701 pin 19 & 20
Replace U5701
RF level at
T5061 pin 4
about -20dBm
?
Set IFR TX Frequency
to 73.35MHz
RF level at
TP5201 about
-30dBm
?
Check components
between
U5201 and T5061
Check
D5061, T5062
RF level at
TP5202 about
-30dBm
?
Replace U5201
RF level at
Q5031 Collector
about -22dBm
?
4.4V DC at
TP5021
?
Check components
between
Q5031 and antenna
connector.
5.8V DC at
Q5031 Collector
?
Check components
between
Q5031 and T5061
Before replacing U0150
check R5021 and 9.3V
DC at U0150 pin 15
Before replacing Q5031
check: 9.3V DC at C5002,
0V DC at C5001.
Check Q5001 and
associated components.
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Failure:
Bit Error Rate @ -114dBm >3.5%
RSSI error >+/- 5dB
PATS parameter GAIN_OFF_L, GAIN_OFF_H and
AGC_SLOPE failed.
Tetra Com Script for RX Test
TEST_ENTER
DELAY 18
Check for "Radio HW is READY"
MODE IDLE
FREQ RX 460.025
L1TIMER ON
AVE 10
MODE RSSI
GO
Use STOP to terminate RSSI reading
Connect the radio's accessory connector to the
Tetra Com interface.
Connect the radio's antenna connector to the high
power RF output on the IFR.
Connect the 50ohms RF probe to the low power
RF input on the IFR
Setup IFR:
Select high power output and low power input
No System,
Duplex Test,
Generator Frequency 460.025MHz,
TX Frequency 386.675MHz
Generator Level -30dBm,
Duplex Test TX,
Spectrum Analyser
Set Reference Level to 10dBm
Run Tetra Com script for RX test
Measure RF levels and frequencies with the
50ohms RF probe.
Measure DC levels with a multimeter.
ZWG0130968-O
Receiver Chart 1
UHF
A
No
No
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6866539D31.book Page 14 Tuesday, March 20, 2007 6:32 PM