Troubleshooting
6-86
TDS 420A, TDS 430A & TDS 460A Service Manual
Figure 6- 35: Power Supply Overload Troubleshooting Procedure
Yes
No
Yes
No
No
Yes
Use this procedure to
troubleshoot a power supply
overload problem.
CAUTION: Turn the oscilloscope
power off before removing a board or
disconnecting a cable.
Remove loads one at a time (remove
each plug-in circuit board and
disconnect cables from the
A01 Backplane).
Does
the supply work
ok when a specific
board or cable is
removed?
Replace board or cable that
has the fault.
Does
the supply work ok
when all boards and
cables are removed?
Replace the
A01 Backplane.
No
Yes
Does
the
supply work ok
when the load is
reduced by removing or
disconnecting one or more boards
or cables, but not due to
an overload or short on
a specific board
or cable?
Replace the A25 Low Voltage
Power Supply.
Check the current drawn from the
power supply secondary.
Does
the current
drawn exceed the
specification shown in
Table 6--12?
Check and repair the circuit.
Replace the A25 Low Voltage
Power Supply.
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