IBM 8676 Hardware Maintenance Manual - Page 36

Light, Diagnostics, Level, diagnostic, panel

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Light Path Diagnostics The Light Path Diagnostics LEDs help you to identify problems with server components. By following the light path, you can quickly identify and fix the type of problem that occurred. The light path begins with the LEDs on the front panel of the server. If the server encounters a problem, it lights either the Information LED or the Error LED. To isolate the source of a problem, remove the server from the rack, remove the top cover and examine the level 2 Light Path Diagnostics LEDs on the system board (see "Level 2 diagnostic panel LEDs"). These LEDs can indicate a problem with a single component, or a problem with one of several similar components. In the latter case, to isolate the specific failing component, look for a lit LED on the system board or next to a component. For example, if the level 2 FAN LED is lit, the specific failing fan is indicated by an LED next to the fan. If the MEM LED is lit, the specific failing DIMM is indicated by an LED next to the DIMM. The level 2 diagnostic LED panel is located on the system board. If you press the Light Path button (SW1, next to the NON OPT LED), the Circuit OK LED (CR82, next to the TEMP LED) will illuminate. This shows that the diagnostic circuitry is working correctly. The server is designed so that any LEDs that are illuminated can be illuminated again without ac power after you remove the cover. This feature helps you isolate the problem if an error causes the server to shut down. See "Light Path Diagnostic panel system error LED" on page 82. Important: You have up to 12 hours to use the Light Path Diagnostic LEDs after ac power has been removed from the server. After 12 hours, you must power-on the server again to be able to use the Light Path Diagnostic LEDs to help locate system errors. To view the LEDs on the system board: 1. Turn off the server and peripheral devices. 2. Remove all external cables from the server; then, remove the server from the rack and remove the cover (see "Removing the cover and bezel" on page 44). 3. Press and hold the Light Path Diagnostics (blue) button on the system board at the right front of the LED cluster. The error-indicating LEDs will light while the switch is pressed. Take corrective action for the indicated error (see "Light Path Diagnostic panel system error LED" on page 82). Note: You can light the LEDs for a maximum of two minutes. After that time, the circuit that powers the LEDs is exhausted. 4. Replace the cover on the server (see "Installing the cover and bezel" on page 59); then, reinstall the server in the rack and connect all external cables. Level 2 diagnostic panel LEDs The Light Path Diagnostics feature might direct you to look for an LED on the system board that identifies the specific failing component. The following illustration shows the location of the level 2 diagnostic LED panel on the system board. 26 xSeries 335 Type 8676, Type 8830: Hardware Maintenance Manual and Troubleshooting Guide

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Light
Path
Diagnostics
The
Light
Path
Diagnostics
LEDs
help
you
to
identify
problems
with
server
components.
By
following
the
light
path,
you
can
quickly
identify
and
fix
the
type
of
problem
that
occurred.
The
light
path
begins
with
the
LEDs
on
the
front
panel
of
the
server.
If
the
server
encounters
a
problem,
it
lights
either
the
Information
LED
or
the
Error
LED.
To
isolate
the
source
of
a
problem,
remove
the
server
from
the
rack,
remove
the
top
cover
and
examine
the
level
2
Light
Path
Diagnostics
LEDs
on
the
system
board
(see
“Level
2
diagnostic
panel
LEDs”).
These
LEDs
can
indicate
a
problem
with
a
single
component,
or
a
problem
with
one
of
several
similar
components.
In
the
latter
case,
to
isolate
the
specific
failing
component,
look
for
a
lit
LED
on
the
system
board
or
next
to
a
component.
For
example,
if
the
level
2
FAN
LED
is
lit,
the
specific
failing
fan
is
indicated
by
an
LED
next
to
the
fan.
If
the
MEM
LED
is
lit,
the
specific
failing
DIMM
is
indicated
by
an
LED
next
to
the
DIMM.
The
level
2
diagnostic
LED
panel
is
located
on
the
system
board.
If
you
press
the
Light
Path
button
(SW1,
next
to
the
NON
OPT
LED),
the
Circuit
OK
LED
(CR82,
next
to
the
TEMP
LED)
will
illuminate.
This
shows
that
the
diagnostic
circuitry
is
working
correctly.
The
server
is
designed
so
that
any
LEDs
that
are
illuminated
can
be
illuminated
again
without
ac
power
after
you
remove
the
cover.
This
feature
helps
you
isolate
the
problem
if
an
error
causes
the
server
to
shut
down.
See
“Light
Path
Diagnostic
panel
system
error
LED”
on
page
82.
Important:
You
have
up
to
12
hours
to
use
the
Light
Path
Diagnostic
LEDs
after
ac
power
has
been
removed
from
the
server.
After
12
hours,
you
must
power-on
the
server
again
to
be
able
to
use
the
Light
Path
Diagnostic
LEDs
to
help
locate
system
errors.
To
view
the
LEDs
on
the
system
board:
1.
Turn
off
the
server
and
peripheral
devices.
2.
Remove
all
external
cables
from
the
server;
then,
remove
the
server
from
the
rack
and
remove
the
cover
(see
“Removing
the
cover
and
bezel”
on
page
44).
3.
Press
and
hold
the
Light
Path
Diagnostics
(blue)
button
on
the
system
board
at
the
right
front
of
the
LED
cluster.
The
error-indicating
LEDs
will
light
while
the
switch
is
pressed.
Take
corrective
action
for
the
indicated
error
(see
“Light
Path
Diagnostic
panel
system
error
LED”
on
page
82).
Note:
You
can
light
the
LEDs
for
a
maximum
of
two
minutes.
After
that
time,
the
circuit
that
powers
the
LEDs
is
exhausted.
4.
Replace
the
cover
on
the
server
(see
“Installing
the
cover
and
bezel”
on
page
59);
then,
reinstall
the
server
in
the
rack
and
connect
all
external
cables.
Level
2
diagnostic
panel
LEDs
The
Light
Path
Diagnostics
feature
might
direct
you
to
look
for
an
LED
on
the
system
board
that
identifies
the
specific
failing
component.
The
following
illustration
shows
the
location
of
the
level
2
diagnostic
LED
panel
on
the
system
board.
26
xSeries
335
Type
8676,
Type
8830:
Hardware
Maintenance
Manual
and
Troubleshooting
Guide