224
Frequency Synthesizer Fault Finding
TM8100/TM8200 Service Manual
© Tait Electronics Limited
June 2006
Task 31 —
Check Transmit-
Receive Switch
If no frequency is detected in the check of the VCO, first check that the
transmit-receive switch is functioning correctly.
1.
Resolder
R542
in position (see
2.
Remove the
VCO
BOT
can.
3.
Enter the CCTM command
335 0
to switch on the supply to the
RX
port.
4.
Measure the voltage at pin 2 of
D5004
(see
). (Some RF
noise might be observed.) The voltage should be:
5.
Enter the CCTM command
335 1
to switch off the supply.
6.
Again measure the voltage at pin 2 of
D5004
.
7.
If the voltages measured in
and
are correct, go to
. If they are not, the switching network is suspect; go to
.
8.
Enter the CCTM command
335 1
to switch on the supply to the
TX
port.
9.
Measure the voltage at pin 1 of
D5004
(see
). (Some RF
noise might be observed.) The voltage should be:
10.
Enter the CCTM command
335 0
to switch off the supply.
11.
Again measure the voltage at pin 1 of
D5004
.
12.
If the voltages measured in
and
are correct, go to
. If they are not, the switching network is suspect; go to
.
pin 2 of D5004: 5.0
±
0.3 V DC (after entry of CCTM 335 0)
pin 2 of D5004: 0 V DC (after entry of CCTM 335 1)
pin 1 of D5004: 5.0
±
0.3 V DC (after entry of CCTM 335 1)
pin 1 of D5004: 2.1
±
0.4 V DC (after entry of CCTM 335 0)
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...