TM8100/TM8200 Service Manual
Frequency Synthesizer Fault Finding
199
© Tait Electronics Limited
June 2006
Task 12 —
VCO Faulty
If the loop voltage is correct, the loop filter is functioning properly.
The VCO and related circuitry is therefore suspect. The section to proceed
to depends on the type of the radio and the nature of the fault.
1.
With a UHF radio go to
. With a VHF radio go to
Related Circuitry (VHF Radios)” on page 217
2.
If a UHF radio exhibits a lock error or a receive fault. the receive
VCO is suspect; go to
“Receive VCO and Related Circuitry (UHF
.
If it exhibits a system error or a transmit fault, the transmit VCO is
suspect; go to
“Transmit VCO and Related Circuitry (UHF
.
Task 13 —
Check Reference
Voltage
If the loop-filter circuitry is suspect, first check the reference voltage for
the filter.
1.
Remove the
SYN
BOT
can.
2.
Measure the reference voltage at pin 5 of
IC505
(see
).
The result should be:
3.
If the voltage is correct, go to
. If it is not, the reference-
voltage circuitry is suspect; go to
4.
Resolder
R542
in position and check the C-multiplier
Q512
(see
5.
If a fault is found, repair the circuit, and confirm that the reference
voltage is now correct. If it is, go to
. If it
is not, or if no fault could be found, replace the board and go to
.
IC505 pin 5:
2.8
±
0.1 V DC
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...