HP ProDesk 600 G1 Maintenance And Service Manual page 160

Check the Power LED on the front of the computer to see if it is flashing red. The flashing lights are
error codes that will help you diagnose the problem. Refer to Appendix A,
on page 187
Turn up the brightness and contrast controls of the monitor if the monitor is dim.
Press and hold any key. If the system beeps, then the keyboard should be operating correctly.
Check all cable connections for loose connections or incorrect connections.
Wake the computer by pressing any key on the keyboard or pressing the power button. If the
system remains in suspend mode, shut down the computer by pressing and holding the power
button for at least four seconds then press the power button again to restart the computer. If the
system will not shut down, unplug the power cord, wait a few seconds, then plug it in again. The
computer will restart if it is set to power on automatically as soon as power is restored in
Computer Setup. If it does not restart, press the power button to start the computer.
Reconfigure the computer after installing a non-plug and play expansion board or other option.
See Solving Hardware Installation Problems on page 171
Be sure that all the needed device drivers have been installed. For example, if you are using a
printer, you need a driver for that model printer.
Remove all bootable media (CD/DVD or USB device) from the system before turning it on.
If you have installed an operating system other than the factory-installed operating system, check
to be sure that it is supported on the system.
If the system has multiple video sources (embedded, PCI, or PCI-Express adapters) installed
(embedded video on some models only) and a single monitor, the monitor must be plugged into
the monitor connector on the source selected as the primary VGA adapter. During boot, the other
monitor connectors are disabled and if the monitor is connected into these ports, the monitor will
not function. You can select which source will be the default VGA source in Computer Setup.
CAUTION:
applied to the system board. You must disconnect the power cord from the power source before
opening the computer to prevent system board or component damage.
150 Chapter 8 Troubleshooting without diagnostics
for more information.
When the computer is plugged into an AC power source, there is always voltage
POST error messages
for instructions.