382
CODEC and Audio Fault Finding
TM8100/TM8200 Service Manual
© Tait Electronics Limited
June 2006
13.1
Power Supplies
Introduction
First check that a power supply is not the cause of the fault. Of these
supplies, the 3.3V DC supply (
+3
V
3
) will already have been checked in
“Power Supply Fault Finding” on page 163
. The remaining supplies that
need to be checked are:
■
: 9V DC supply from 9V regulator (
+9
V
0
)
■
: 3V DC supply from 3V regulator (
+3
V
0
AN
)
■
: 2.5V DC supply from 2.5V regulator (
+2
V
5
CDC
)
Two other supplies used in the CODEC and audio circuitry are a 1.8V DC
supply (
+1
V
8
) from the digital board and the 13.8V DC supply (
+13
V
8
BATT
)
from the power connector. Faults in these supplies are dealt with elsewhere.
Task 1 —
9V Power Supply
First check the 9V DC supply (
+9
V
0
), which is required by IC201.
1.
Remove the board from the chassis.
2.
Remove the
CDC
BOT
can.
3.
Measure the voltage
+9
V
0
at pin 4 of
IC201
(see
4.
If the voltage is correct, go to
. If it is not, go to
5.
The fault will be at
IC201
(see
), since any fault with the
9V regulator in the PSU module will already have been rectified.
Therefore, check the soldering of IC201. Repair any fault.
6.
Confirm the removal of the fault and go to
. If the repair failed or the fault could not be found, replace
the board and go to
Task 2 —
3V Power Supply
If the 9V supply is correct, check the 3V DC supply (
+3
V
0
AN
) next.
1.
Measure the voltage
+3
V
0
AN
at the
TP
601
test point
(see
2.
If the voltage is correct, go to
. If it is not, go to
3.
The 3V regulator
IC603
is suspect (see
). Check the
regulator as described in
“Power Supply Fault Finding” on
pin 4 of IC201: 9.0
±
0.3V DC
TP601 test point: 2.9
±
0.3V 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...
