HP 280 G4 MT Maintenance And Service Manual page 64

Computer date and time display is incorrect.
Cause
RTC (real-time clock) battery may need to be replaced.
NOTE: Connecting the computer to a live AC outlet prolongs the
life of the RTC battery.
Cursor will not move using the
Cause
The Num Lock
There is no sound or sound volume is too low.
Cause
System volume may be set low or muted.
Cannot remove computer cover or access panel.
Cause
Smart Cover Lock, featured on some computers, is locked.
56 Chapter 6 Troubleshooting without diagnostics
arrow keys on the keypad.
key is turned on.
Solution
Reset the date and time under Control Panel (Computer Setup can
also be used to update the RTC date and time). If the problem
persists, replace the RTC battery. See the Removal and
Replacement section for instructions on installing a new battery, or
contact an authorized dealer or reseller for RTC battery
replacement.
To access Control Panel in Windows 7, select Start, and then select
Control Panel.
To access Control Panel in Windows 10, type control panel in
the taskbar search box, and then select Control Panel.
Solution
Press the Num Lock key. The Num Lock light must be off if you want
to use the arrow keys on the keypad. You can also disable or enable
the Num Lock key in Computer Setup at Advanced > Device Options.
Solution
1. Check the Computer Setup settings to make sure the internal
system speaker is not muted (this setting does not affect the
external speakers).
2. Make sure the external speakers are properly connected and
powered on and that the speakers' volume control is set
correctly.
3. Use the system volume control available in the operating
system to make sure the speakers are not muted or to
increase the volume.
Solution
Unlock the Smart Cover Lock using Computer Setup.
In case of forgotten password, power loss, or computer
malfunction, you must manually disable the Smart Cover lock . A
key to unlock the Smart Cover Lock is not available from HP. Keys
are typically available from a hardware store.