TM8100/TM8200 Service Manual Frequency Synthesizer Fault Finding 191
© Tait Electronics Limited November 2007
Task 3 —
14V Power Supply
(B1 50W and K5:
15.5V)
First check the output VCL SUPPLY from the SMPS, which is itself provided
with a 9V DC supply from a 9V regulator in the PSU module.
1. Remove the board from the chassis.
2. Place the radio in CCTM.
3. Measure the SMPS output
VCL SUPPLY at the via between C531 and
R530 (see Figure 9.2).
Note On A4 band radios, C531 and R530 are on the bottom side of the
PCB. Measure the
VCL SUPPLY voltage on the via beside C5050.
4. If the SMPS output is correct, go to Tas k 4
. If it is not, go to Step 5.
5. Check the 9V supply at Q500 and R533 (see Figure 9.3).
6. If the voltage is correct, go to Step 7. If it is not, the 9V regulator
IC601 is suspect; go to Tas k 3
of “Power Supply Fault Finding” on
page 174.
7. Remove the
FCL TOP can and check the SMPS circuit based on Q500,
Q502 and L502 (see Figure 9.3).
Figure 9.2 Synthesizer circuitry under the SYN TOP can and the 6V regulator IC606 (top side) (cont.)
K5 band
Q512
Junction of
C541 and R547
Q508
Q506 Q507
TP503
C531: 14.2V ± 0.3 DC
B1 50W from board revision -04 and K5: 15.5V ± 0.3 DC
Q500 and R533: 9.0V ± 0.3 DC
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