Universal Serial Bus (USB) port problemsv Follow the suggested actions in the order in which they are listed in the Action column until the problemis solved.v See Chapter 4, “Parts listing, System x3550 M3 Types 4254 and 7944,” on page 159 to determine whichcomponents are customer replaceable units (CRU) and which components are field replaceable units(FRU).v If an action step is preceded by “(Trained service technician only),” that step must be performed only by aTrained service technician.v Go to the IBM support Web site at http://www.ibm.com/systems/support/ to check for technicalinformation, hints, tips, and new device drivers or to submit a request for information.Symptom ActionA USB device does not work. 1. Make sure that:v The correct USB device driver is installed.v The operating system supports USB devices.2. Make sure that the USB configuration options are set correctly in the Setuputility (see “Using the Setup utility” on page 259 for more information).3. If you are using a USB hub, disconnect the USB device from the hub andconnect it directly to the server.Video problemsSee “Monitor and video problems” on page 93.Light path diagnosticsLight path diagnostics is a system of LEDs on various external and internalcomponents of the server. When an error occurs, LEDs are lit throughout theserver. By viewing the LEDs in a particular order, you can often identify the sourceof the error.When LEDs are lit to indicate an error, they remain lit when the server is turned off,provided that the server is still connected to power and the power supply isoperating correctly.Before you work inside the server to view light path diagnostics LEDs, read thesafety information that begins on page “Safety” on page vii and “Handlingstatic-sensitive devices” on page 169.If an error occurs, view the light path diagnostics LEDs in the following order:1. Look at the operator information panel on the front of the server.v If the information LED is lit, it indicates that information about a suboptimalcondition in the server is available in the IMM system-event log or in thesystem-error log.v If the system-error LED is lit, it indicates that an error has occurred; go tostep 2.The following illustration shows the operator information panel:Chapter 3. Diagnostics 101
