Tait TM8100 mobiles Service Manual page 170

Task 1 —
Check Inputs to
SMPS
170 Power Supply Fault Finding
The test equipment and radio should be set up as described in
the Test Equipment" on page
Connect the control head to the assembly. Then check the SMPS as follows:
1. Use a multimeter to check the supply voltage at pin 7 of IC602
(see Figure 7.1) in the SMPS circuitry; the voltage should be:
pin 7 of IC602: 13.8 V DC
If it is, go to Step
2. Disconnect the 13.8V supply at the power connector PL100. Check
for continuity and shorts to ground in the path between the power
connector PL100 and pin 7 of IC602 (see
repair the fault.
3. Reconnect the 13.8V supply. Confirm the removal of the fault by
measuring the voltage at pin 7 of IC602. If the voltage is correct,
continue with Step
and go to "Final Tasks" on page
/
4. Press the
ON OFF
on page 155. If it does not, go to
5. Check the digital power-up signal at pin 5 of IC602
(see Figure 7.1); the signal is active high, namely, when the voltage
exceeds 2.0V DC. Measure the voltage at pin 5.
pin 5 of IC602: more than 2.0 V DC
If it exceeds 2.0V, go to
6. Keep the probe of the multimeter on pin 5 of IC602 and press the
/
key. The voltage should exceed 2.0V DC while the key is
ON OFF
depressed. If it does, go to
7. Disconnect the 13.8V supply at the power connector PL100. Check
for continuity and shorts to ground in the path from pin 5 of IC602,
via R600 and via Q709 in the interface circuitry (see
pin 9 of the control-head connector SK100 (
Locate and repair the fault. Go to
8. Reconnect the 13.8V supply. Press the
up, return to "Initial Tasks" on page
9. With the probe of the multimeter on pin 5 of IC602 (see
/
press the
ON OFF
while the key is depressed. If it does, go to
repair failed; replace the board and go to
115. If not already done, remove the board.
5. If it is not, go to Step
4. If it is not, the repair failed; replace the board
163.
key. If the radio powers up, return to
Step
Task 2. If it does not, go to
Task 2. If it does not, go to
Step
155. If it does not, go to
key again. The voltage should exceed 2.0V DC
© Tait Electronics Limited November 2007
"Setting up
2.
Figure 7.1). Locate and
"Initial Tasks"
5.
Step 6.
Step 7.
Figure
line).
ITF PSU ON OFF
8.
/
key. If the radio powers
ON OFF
Figure
Task 2. If it does not, the
"Final Tasks" on page
TM8100/TM8200 Service Manual
8.4), to
Step 9.
7.1),
163.