2.5V Power Supply - Tait TM9100 Service Manual

If the 9V and 3V supplies are correct, the remaining power supply to check
Task 3 —

2.5V Power Supply

is the 2.5V DC supply (+2
1.
2.
3.
4.
374 CODEC and Audio Fault Finding
5
V CDC
Measure the voltage +2 5
V
pin 5 of IC604: 2.5 ± 0.3V DC
If the voltage is correct, go to
The 2.5V regulator IC604 is suspect (see
regulator as described in
page 158.
Proceed to the section relevant to the fault exhibited:
"Faulty Speaker Audio"
"No Speaker Audio at Auxiliary Connector"
auxiliary connector)
"Faulty Receiver" (receiver does not operate)
"Faulty Modulation"
"Faulty Modulation Using Auxiliary Connector"
auxiliary connector only)
Further details are given in the introduction to the section.
).
at pin 5 of IC604 (see
CDC
Step 4. If it is not, go to
Figure
Task 3 of "Power Supply Fault Finding" on
(distorted or no speaker audio)
(no speaker audio at
(distorted or no transmit modulation)
© Tait Electronics Limited August 2005
Figure 13.1).
Step 3.
13.1). Check the
(modulation at
TM9100 Service Manual