Tait TM8235, Service Manual

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TM8100/TM8200 Service Manual Power Supply Fault Finding 163
© Tait Electronics Limited June 2006
7 Power Supply Fault Finding
Fault-Diagnosis
Tasks
Fault diagnosis of the power-supply circuitry is divided into the following
tasks:
■
Task 1 : check inputs to SMPS
■
Task 2 : check 3.3V supply
■
Task 3 : check linear regulators (for 2.5V, 3V, 6V and 9V supplies)
■
Task 4 : check power-up configuration
■
Task 5 : check power-up options
■
Task 6 : check provision of external power.
Types of Fault
Which of the above tasks are applicable depends on the nature of the fault:
■
Radio fails to power up: The radio fails to power up immediately when
power is applied, or it fails to power up when power is applied and the
ON
/
OFF
key is pressed. Carry out Task 1 to Task 3
■
Power-up option has failed: The radio powers up when the
ON
/
OFF
key is
pressed, but not for a power-up option for which it is configured.
Carry out
Task 4 and Task 5 .
■
External power at connector has failed: The external power required at
a particular connector is no longer present. Carry out
Task 6 .