IBM 7870B4U, Service Manual

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Light path diagnostics
Use this information as an overview of light path diagnostics.
Light path diagnostics is a system of LEDs on the control panel and on various
internal components of the blade server or expansion unit. When an error occurs,
LEDs can be lit throughout the blade server or expansion unit to help identify the
source of the error.
After you remove the blade server or expansion unit, you can press and hold the
light path diagnostics switch for a maximum of 25 seconds to light the LEDs and
locate the failing component.
Viewing the light path diagnostics LEDs in the blade server
Use this information to locate and identify the light path diagnostics LEDs.
Before you work inside the blade server to view light path diagnostics LEDs, read
“Safety” on page v and “Installation guidelines” on page 49.
If an error occurs, view the light path diagnostics LEDs in the following order:
1. Look at the control panel on the front of the blade server (see “Blade server
controls and LEDs” on page 11).
v
If the information LED is lit, it indicates that information about a suboptimal
condition in the blade server is available in the IMM log or in the
Advanced-Management-Module event log.
v
If the blade-error LED is lit, it indicates that an error has occurred; view the
light path diagnostics panel and LEDs to isolate the failing component.
2.
To view the light path diagnostics panel and LEDs, complete the following
steps:
a. Remove the blade server from the BladeCenter unit. See “Removing the
blade server from the BladeCenter unit” on page 52.
b. Place the blade server on a flat, static-protective surface.
c. Remove the cover from the blade server. See “Removing the blade server
cover” on page 55.
d. Press and hold the light path diagnostics switch to light the LEDs of the
failing components in the blade server. The LEDs will remain lit for as long
as you press the switch, to a maximum of 25 seconds.
Chapter 6. Diagnostics
183