TM9100 Service Manual
Frequency Synthesizer Fault Finding
191
© Tait Electronics Limited
August 2005
Task 16 —
Check
TP
503 Test
Point
If the reference voltage, feedback voltage, and
DIG
SYN
FAST
line are all
correct, check the voltage at the
TP
503
test point.
1.
Measure the voltage at the
TP
503
test point
(see
Figure 9.7
).
The oscilloscope should show a DC level less than 3.0 V with no sign
of noise or modulation.
2.
If the correct result is obtained, go to
Step 3
. If it is not, go to
Step 4
.
3.
The loop filter is faulty but the above measurements do not provide
more specific information. Check IC504, IC505, Q511
(see
Figure 9.4
), C5085 to C5089 (B1 band, see
Figure 9.7
) or
C5085
and C5086 (H5, H6 bands see
Figure 9.7
), and associated
components. Conclude with
Step 9
.
4.
Remove R566 and R570 (see
Figure 9.7
), which provide a
modulation path to the VCO(s).
5.
Repeat the measurement of
Step 1
.
6.
If the correct result is now obtained, go to
Step 7
. If the correct result
is still not obtained, the CODEC and audio circuitry is suspect;
resolder R566 and R570 in position (see
Figure 9.7
), and go to
“CODEC and Audio Fault Finding” on page 371
.
7.
Resolder R566 and R570 in position (see
Figure 9.7
).
8.
Check IC504 (pins 6, 8, 9) (see
Figure 9.4
) and the associated
components in the loop filter.
9.
If a fault is found, repair the circuit, and confirm that the voltages are
now correct. If they are, go to
“Final Tasks” on page 147
. If they are
not, or if no fault could be found, replace the main-board assembly
and go to
“Final Tasks” on page 147
.
TP503 test point: < 3.0 V DC
Summary of Contents for TM9100
Page 1: ...TM9100 mobiles Service Manual MMA 00017 01 Issue 1 August 2005 ...
Page 4: ...4 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 10: ...10 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 22: ...22 Introduction TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 62: ...62 Description TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 96: ...96 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 138: ...138 Disassembly and Reassembly TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 152: ...152 Servicing Procedures TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 168: ...168 Interface Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 244: ...244 Receiver Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 396: ...396 CODEC and Audio Fault Finding TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 420: ...420 Fault Finding of Control Head TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 426: ...426 Spare Parts TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 430: ...430 TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 444: ...444 TMAA04 05 Ignition Sense Kit TM9100 Service Manual Tait Electronics Limited August 2005 ...
Page 448: ...448 TMAA10 01 Desktop Microphone TM9100 Service Manual Tait Electronics Limited August 2005 ...