User Manual
ADCP-75-136 • Issue 1 • November 2002
Page 44
©
2002,
ADC
Telecommunications,
Inc.
6.3 Fault Isolation and Troubleshooting
Fault
isolation
and
troubleshooting
guidelines
are
provided
in
Tables
11,
12,
13,
and
14.
When
an
alarm
is
reported,
determine
the
type
of
alarm
generated
(minor
or
major)
and
then
check
the
LED
indicators
on
the
DHU
and
note
any
that
are
red,
yellow,
or
off.
If
any
of
the
Port
1–6
OK/NOK
LED
indicators
on
the
DHU
are
red
or
yellow,
also
check
the
LED
indicators
on
the
connected
DEU’s
and/or
DRU’s
and
note
if
any
are
red
or
yellow.
Start
the
troubleshooting
process
at
the
DHU
and
then
work
toward
the
unit
where
the
alarm
originated.
The
troubleshooting
tables
are
organized
according
to
unit
type.
Locate
the
problem
in
the
appropriate
table,
check
out
the
suggested
possible
causes,
and
take
corrective
action
as
required.
Figure
24
shows
two
basic
ICS
system
configurations.
The
troubleshooting
tables
list
possible
causes
for
various
problems.
If
the
cause
of
a
particular
problem
is
specific
to
either
of
the
two
system
configurations
shown
in
Figure
24,
the
type
of
system
configuration
(1
or
2)
will
be
referenced
in
the
table.
17962-A
FWD
REV
DRU
FWD
REV
DRU
FWD
REV
DIGITAL EXPANSION UNITDIGITAL HOST UNIT
DIGITAL HOST UNIT
(2)
(1)
Figure 24. ICS System Basic Configurations
Table 11. DHU Fault Isolation and Troubleshooting Guidelines
Alarm Type LED LED COLOR
Minor
UNIT
Yellow
Problem : The DHU is overheating.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1.
Air
intake
or
exhaust
openings
to
DHU
chassis
blocked.
2.
Ambient
temperature
>
50º
C/122º
F.
3.
Faulty
fan.
1.
Remove
cause
of
air-flow
blockage.
2.
Reduce
ambient
temperature.
3.
Replace
fan
(see
Subsection
6.5).
Alarm Type LED LED COLOR
Major
UNIT
Red
Problem : The DHU detects an internal circuitry fault.
POSSIBLE CAUSE CORRECTIVE ACTION/COMMENTS
1.
Faulty
DHU.
1.
Replace
DHU.
(Continued)