IBM 8688 manual Diagnostics panel, LEDs on the top of the server, LEDs on the system boards

error that occurred, and see “Light Path LED errors” on page 147 to help determine the cause of the error and the action you should take.

To view the LEDs on the various main boards, look at the board indicated by the diagnostic panel.

To acknowledge a system error but not take immediate action, press the REMIND button, and place the Light Path Diagnostics feature in Remind mode. The system-error LED flashes in Remind mode. If a new failure occurs, the system-error LED is lit again.

The diagnostics panel

The diagnostics panel should be the first place you look for help with identifying problems. If a system error occurs, the system-error LED on the front of this panel is lit. Press the front of the panel to open the diagnostics panel, and look for any lit LEDs. These lit LEDs can help you identify the possible cause of the error. Make a note of any LEDs that are lit, and then close the panel.

LEDs on the top of the server

You can also use the LEDs on the top of the server to find an error. If the BOARD LED on the diagnostics panel is lit, pull the server out, and view the top cover. In the center of the top cover is a set of six LEDs and the system service labels. The numbers next to the LEDs correspond to the numbers on the system service label. Note the lit LED, and see the numbered block on the system service label that corresponds to the lit LED. Then, follow the instructions, if any, in the numbered block.

LEDs on the system boards

To locate the actual component that caused the error, locate the lit LED next to that component.

For example:

A system error has occurred, and you have noted that the CPU LED is lit on the diagnostics panel. Referring to the LEDs on the top cover, you see that LED 2 is lit. You then locate the panel on the system service label with the number 2 on it. In this case, the instructions in the panel tell you that the problem occurred with one of the microprocessors. Follow the instructions to remove the processor-board assembly. See “Processor-board assembly” on page 119. Located on the circuit board is the light-path capacitor switch. Press and hold the switch until you locate the lit LED next to the defective microprocessor. Follow the instructions in “Microprocessor and power module” on page 121 and “Installing and replacing a microprocessor and power module” on page 100 to remove and replace the microprocessor.

For more information about LEDs and connectors, see “Connector and LED locations” on page 80.

Diagnostic display

If a problem is detected with system power on or during initialization, the two-hex character diagnostic display on the midplane board might show an error code. See “Midplane board connectors and LEDs” on page 84 and “Diagnostic display error codes” on page 181 for more information.

Chapter 3. Diagnostics 37