Tait TP9100 - Page 166

166 Frequency Synthesizer Fault Finding TP9100 Service Manual
© Tait Electronics Limited May 2005
Task 4 —
5V Power Supply
If the output of the SMPS is correct, check the 5V DC supply next.
1. Measure the supply +5
V0 at pin 4 of IC601 (see Figure 9.3).
2. If the voltage is correct, go to Tas k 5
. If it is not, measure the 7V5 LINK
input at pin 6 of IC601 (see Figure 9.3).
3. If the voltage is correct, go to Step 4. If it is not, the 7.5V supply is
faulty. Go to “Power Supply Fault Finding” on page 149.
4. If the input to the regulator IC601 is correct but not the output,
check IC601 (see Figure 9.3) and the associated circuitry;
if necessary, replace IC601.
Remove the
SYN TOP can and check the C-multipliers Q508 (pins 3,
4, 5) (see Figure 9.3).
5. If a fault is found, repair the circuit, confirm the removal of the fault,
and go to “Final Tasks” on page 134. If the repair failed or no fault
could be found, replace the main board, and go to “Final Tasks” on
page 134.
pin 4 of IC606: 5.0 ± 0.02V DC
pin 6 of IC601: 7.5V (battery voltage)