Acer Altos R480 F4 User Manual page 14

Peripheral device connected to a USB port does not work.
Do the following:

Reduce the number of external devices connected to a USB hub.

Refer to the documentation that came with the device
There is problem with the software program.
Do the following:

Verify that the software is properly configured for the system.

Refer to the software installation and operation documentation for instructions on
setting up and using the software. Try a different version of the software to see if the
problem is with the copy you are using. If the other version runs correctly on the
system, contact your vendor about the defective software.
No characters appear on the display monitor.
Do the following:

Is the keyboard functioning? Test it by turning the Num Lock function on and off to
check if the Num Lock indicator lights up.

Is the display monitor plugged in and turned on? If you are using a switch box, is it
switched to the correct system?

Are the brightness and contrast controls on the video monitor properly adjusted?

Is the display monitor signal cable properly connected?

Does this display monitor work correctly if plugged into a different system?

Remove all add-in cards and see if the system boots.
If reboot is successful, install the cards back in one at a time with a reboot between
each addition to determine if one of them is causing the problem.

Make sure that you have properly installed system-compliant memory modules, and
that they are populated according to the system guidelines.

Make sure that you have installed system compliant processors, and that they are
populated according to the system guidelines.
If you are using an add-in video controller card, do the following:
1. Verify that the display monitor works using the onboard video controller.
2. Verify that the add-in video controller card is fully seated in its slot.