Power-Supply Circuitry Under The Cdc Bot Can; Check Linear Regulators; Power Supply Fault Finding - Tait TM9100 Service Manual

Figure 7.3 Power-supply circuitry under the
regulator IC604
CAN FOR
DIGITAL
BOARD
This task describes the general procedure for checking any linear regulator.
Task 3 —
Check Linear
There are two possible faults: either the regulator has failed and prevents the
Regulators
radio from powering up, or the regulator voltage is incorrect. (The regulator
IC might or might not have been removed during earlier checks.)
1.
2.
3.
4.
158

Power Supply Fault Finding

can, including 3V regulator IC603 and 2.5V
CDC BOT
Disconnect the 13.8 V supply. Check for continuity and shorts to
ground (if not already done) on the input, output and control line of
the relevant regulator IC. Repair any fault.
If the regulator IC has been removed, resolder it in position.
Reconnect the 13.8 V supply and press the
powers up or the correct regulator voltage is restored, return to
"Initial Tasks" on page 139. If the repair failed, go to
Disconnect the 13.8 V supply. Replace the regulator IC with a spare.
Reconnect the 13.8 V supply and press the
powers up or the correct regulator voltage is restored, go to
Tasks" on page 147. If the repair failed, replace the main-board
assembly and go to "Final Tasks" on page
TP601
/
key. If the radio
ON OFF
Step
/
key. If the radio
ON OFF
147.
TM9100 Service Manual
© Tait Electronics Limited August 2005
LO2 BOT CAN
4.
"Final