Tait TM8100 mobiles Service Manual page 401

Figure 13.1 Power-supply circuitry for the CODEC and audio circuitry under the
CAN FOR
DIGITAL
BOARD
Task 3 —
2.5V Power Supply
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
If the 9V and 3V supplies are correct, the remaining power supply to check
is the 2.5V DC supply (+2
Measure the voltage +2
1.
pin 5 of IC604: 2.5 ± 0.3V DC
2. If the voltage is correct, go to
3. The 2.5V regulator IC604 is suspect (see
regulator as described in
page 174.
4. Proceed to the section relevant to the fault exhibited:
"Faulty Speaker Audio"
■
"No Speaker Audio at Auxiliary Connector"
■
auxiliary connector)
"Faulty Receiver"
■
"Faulty Modulation"
■
"Faulty Modulation Using Auxiliary Connector"
■
auxiliary connector only)
Further details are given in the introduction to the section.
5
).
V CDC
5
at pin 5 of IC604 (see
V CDC
Step 4. If it is not, go to
Task 3 of "Power Supply Fault Finding" on
(distorted or no speaker audio)
(receiver does not operate)
(distorted or no transmit modulation)
CODEC and Audio Fault Finding
can
CDC BOT
LO2 BOT CAN
Figure 13.1).
Step 3.
13.1). Check the
Figure
(no speaker audio at
(modulation at
401