Tait TM8115 Service Manual

166 Power Supply Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited June 2006
Task 2 —
Check 3.3V Supply
If the inputs at pin 5 and pin 7 of IC602 in the SMPS circuitry are correct,
but the radio fails to power up, then the 3.3V DC supply needs to be
investigated.
1. First determine as follows if a fault on the digital board is affecting the
supply or preventing the radio from powering up: While keeping the
ON/OFF key depressed, measure the supply at the 3V3 test point near
the corner of the digital board (see Figure 7.2). The voltage is 3.3 V
when there is no fault.
If the voltage is correct, the digital board is faulty; replace the board
and go to “Final Tasks” on page 157. If the voltage is not correct, go
to Step 2.
Figure 7.2 Important components of the power-supply circuitry (top side),
including 9V regulator IC601
3V3 test point
Q600
LK8 (R786)
LK7 (R787)
3V3 test point: 3.3 ± 0.1 V DC

Tait TM8115 Specifications

General

Brand	Tait
Model	TM8115
Category	Radio
Language	English