5V Power Supply - Tait TM9100 Service Manual

If the SMPS output and 6V DC supply are correct, check the +5
Task 5 —

5V Power Supply

supply next.
1.
2.
3.
4.
5.
6.
TM9100 Service Manual
© Tait Electronics Limited August 2005
Remove the can.
SYN TOP
Measure the supply +5
V DEC
pin 4 of Q508: 5.3 ± 0.3V DC
If the voltage is correct, go to
radios) or Step 5 (VHF radios).
With a UHF radio check for faults in the C-multiplier Q508 (pins 3,
4, 5) and the 5V and transmit-receive switches based on Q506, Q507
and Q508 (pins 1, 2, 6) (see
transistor. Conclude with
With a VHF radio check for faults in the C-multiplier and 5V switch
based on Q508 and Q5004 (see
can and check the transmit-receive switch based on Q5002 and
Q5003 (see Figure 9.4). Replace any suspect transistor. Conclude
with Step 6.
If a fault is found, repair the circuit, confirm the removal of the fault,
and go to "Final Tasks" on page
could be found, replace the main-board assembly and go to
Tasks" on page 147.
at pin 4 of Q508 (see
Task 6. If it is not, go to
Figure 9.2). Replace any suspect
Step 6.
Figure 9.2). Remove the
147. If the repair failed or no fault
Frequency Synthesizer Fault Finding
V DEC
Figure 9.2).
Step 4 (UHF
VCO BOT
"Final
179