Troubleshooting
6-84
TDS 420A, TDS 430A & TDS 460A Service Manual
Figure 6- 34: Low Voltage Power Supply Troubleshooting Procedure
Yes
No
Yes
No
No
Yes
It is not an A25 Low Voltage Power
Supply problem. Perform the
Backplane troubleshooting procedure.
Use this procedure to
troubleshoot the Low
Voltage Power Supply.
Is the
principal power switch
(S1) in the on
(in) position?
Press principal power
switch S1 to the on (in)
position.
Is line fuse
F1 ok?
Press principal power
switch S1 to the off (out)
position. Replace the
fuse. Press principal
power switch S1 to the
on (in) position.
Does the fuse
blow?
Disconnect the cable from J1.
Replace the fuse.
Yes
No
Replace the A07 Auxiliary
Power board and t he cables
going to it.
Replace the A25 Low Voltage
Power Supply.
Replace the A25 Low
Voltage Power Supply.
Is there
90--250 VAC at J1 pins 1
and 3 on the A25 Low
Voltage Power Supply?
Is there
90--250 VAC at the
line filter?
Replace the
A07 Auxiliary Power
board.
No
Yes
Is
there power
at the line cord
and outlet?
Replace the line filter.
Fix the power problem.
Are all
secondary voltages
within specification (see
Table 6--11
and Figure 6--36)?
Replace either the
A01 Backplane or the
A03 CPU boards.
Press principal power switch S1 to the off (out)
position. Disconnect the cable (P2) to the
A01 Backplane. Connect a minimum
1 A load to the +5 V supply. Press principal power
switch S1 to the on (in) position.
Perform the Power Supply Overload
troubleshooting procedure.
Yes
No
Does the fuse blow
again?
Yes
No
No
Yes
Yes
No
Yes
Are the
secondary voltages wit hin
specification (see
Table 6--11 and
Figure 6--36)?
No
Press principal power switch S1 to the off
(out) position.
Disconnect the REMOTE_S/D cable (J4)
from the A07 Auxiliary Power board (J4
connects the A07 Auxiliary Power and
A25 Low Voltage Power Supply boards).
WARNING: The power supplies will
come up as soon as principal pow er
switch S1 is in the on (in) position.
Press principal power switch S1 to the on
(in) position.
Are the
secondary voltages
within specification (see
Table 6--11 and
Figure 6--36)?
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