Tait TM8000 Series Service Manual page 175

TM8100 Mobile Radio Service Manual
May 2004 © Tait Electronics Limited
2. Disconnect the 13.8 V supply at the power connector. Remove
R199 [at 1J6/1H8] (see
supply.
With the probe of the multimeter on the 3
3.
/
key. If the voltage is now 3.3 ± 0.1 V, the digital board is
ON OFF
faulty; return to Subsection 2.5.1 and replace the complete main-
board assembly. If the voltage is still not correct, go to Step 4.
4. If the digital board is functional, the fault is on the main board.
Replace R199. Disconnect the 13.8 V supply. Use the
multimeter to measure the resistance between the 3
and ground. If there is a short circuit, continue with Step 5. If
there is no short circuit (but the voltage is wrong), go to Step 7.
5. Search for shorts to ground in the components C603, C612,
C613, C618, D606 [at 6G6 to 6J6/6E6 to 6E8] of the SMPS
circuitry (see Figure
circuitry. Repair any fault and repeat the resistance measurement
of Step 4 to confirm the removal of the fault. If there is no fault,
go to Step 6. If the fault remains, the repair failed; return to
Subsection 8.1
6. Reconnect the 13.8 V supply. Press the
powers up, return to
disconnect the 13.8 V supply and go to Step 7.
7. Measure the resistance of L601 [at 6H6/6E7] (see
The resistance should be virtually zero. If it is, go to Step 8. If it
is not, replace L601. Reconnect the 13.8 V supply and press the
/
key. If the radio powers up, return to
ON OFF
the radio fails to power up, disconnect the 13.8 V supply and go
to Step 8.
8. Remove the
CDC BOT
6H5/6D7] and IC604 (2.5 V regulator) [at 6H3/6C7] (see
Figure 9.3). Reconnect the 13.8 V supply and press the
key. If the 3.3 V supply is restored, go to Task 3 to check each
regulator (3.0 V and 2.5 V) in turn. If the 3.3 V supply is not
restored, continue with Step 9.
9. Suspect IC602 [at 6G7/6E6]. Disconnect the 13.8 V supply.
Replace IC602 with a spare (see
IC604 in position (see
and press the
ON
Subsection 8.1. If the radio fails to power up, the repair failed;
return to Subsection 8.1
assembly.
Figure 9.1). Reconnect the 13.8 V
9.1) as well as in the CODEC and interface
and replace the complete main-board assembly.
Subsection 8.1. If the radio fails to power up,
can. Remove IC603 (3.0 V regulator) [at
Figure
Figure 9.3). Reconnect the 13.8 V supply
/
key. If the radio powers up, return to
OFF
and replace the complete main-board
Diagnosis of Faults on Main Board
3 test point, press the
V
3 test point
V
/
key. If the radio
ON OFF
Figure 9.1).
Subsection 8.1. If
/
ON OFF
9.1). Resolder IC603 and
175