Troubleshooting Power Issues
If your server does not power on, the cause of the problem might be:
AC Power Connection
The AC power cords are the direct connection between the server power supplies and the power sources. The server power supplies need separate stable AC circuits. Insufficient voltage levels or fluctuations in power can cause server power problems. The power supplies are designed to operate at a particular voltage and within an acceptable range of voltage fluctuations (refer to ).
Action: Check that both AC power cords are connected to the server. Check that the correct power is present at the outlets and monitor the power to verify that it is within the acceptable range. You can verify proper connection and operation by checking the power supply (PS) indicator panels, which are located at the back of the server on the power supplies. Lit green AC OK indicators show a properly functioning power supply. An amber AC OK indicator indicates that the AC power to the power supply is insufficient.
Prevention: Use the AC power cord Velcro retaining clips and position the cords to minimize the risk of accidental disconnection. Ensure that the AC circuits that supply power to the server are stable and not overburdened.
Power Supplies (PSUs)
The server power supplies (PSUs) provide the necessary server voltages from the AC power outlets. If the power supplies are inoperable, unplugged, or disengaged from the internal connectors, the server cannot power on.
Note - The Velcro straps shown in the following figure should be used to secure the power cord connectors to the rear of the power supplies. The Velcro retaining straps minimize the risk of accidental disconnection.
Action: Check that the AC cables are connected to both power supplies. Check that the power supplies are operational (the PSU indicator panel should have a lit green AC OK indicator). Ensure that the power supply is properly installed. A power supply that is not fully engaged with its internal connector does not have power applied and does not have a lit green AC OK indicator.
Prevention: When a power supply fails, replace it immediately. To ensure redundancy, the server has two power supplies. This redundant configuration prevents server downtime, or an unexpected shutdown, due to a failed power supply. The redundancy allows the server to continue to operate if one of the power supplies fails. However, when a server is being powered by a single power supply, the redundancy no longer exists, and the risk for downtime or an unexpected shutdown increases. When installing a power supply, ensure that it is fully seated and engaged with its connector inside the drive bay. A properly installed power supply has a lit green AC OK indicator.
Top Cover
The server top cover is an important component for a properly functioning server. The top cover is vital to the server cooling subsystem because it helps to maintain the pressure areas within the server, and the top cover also protects against accidental exposure to hazardous voltages and damage to internal components. For these reasons, the server top cover is interlocked to the server power. The interlock is created by a switch that is mounted inside the server on the housing for the power supply. The switch engages when the cover is installed, allowing power to be applied to the server. When the cover is not installed, the server cannot power on. If the server is powered on when the cover is removed, power is immediately switched off.
Action: If the server does not power on, check that switch is intact and properly aligned. Ensure that the server top cover is in place and sits flat and snug on top of the server. Ensure that the interlock switch components have not been damaged, removed, or misaligned. For instructions for properly installing the top cover, see Install the Server Top Cover.
Prevention: After removing the top cover, take care that it does not get bent. When servicing the server, take care that the internally mounted interlock switch component does not get damaged or misaligned. Never operate the server without the top cover installed.