Try these checks when a screen is blank, says No Signal, or shows a different desktop than expected.
Check power and connections
- Turn on the computer, monitor, and projector you want to use. Check that the dock has power.
- Select the correct input on the monitor or projector, such as HDMI.
- Reseat the accessible video cable and the dock’s USB-C connection to the laptop. Do not force connectors or climb to reach mounted equipment.
- Save your work and restart the computer.
Choose what each screen shows
Mirror or duplicate: show the same content on both screens. Extend: use separate workspace on each screen. A window may be on another screen even when the mouse is visible on this one.
Windows
Press Windows-P and choose Duplicate or Extend. For more options, open Start > Settings > System > Display. Use Identify to match the numbered screens and arrange them. Select Keep changes if prompted and the display looks correct.
Mac
Open Apple menu > System Settings > Displays. Select the connected display, then use Use as to choose mirroring, an extended display, or the main display. These options appear only when a compatible display is connected.
The number of supported displays depends on the Mac, dock, and adapters. If one screen works but another does not, send IT the Mac and dock models rather than assuming every USB-C port or adapter supports another display.
The picture works, but sound goes elsewhere
- Windows: Open Settings > System > Sound and select the intended output.
- Mac: Open System Settings > Sound > Output and select the intended device.
Check the volume and mute setting on both the computer and classroom audio equipment.
Request help
Include the school, room, computer serial number, dock model if visible, and the screen or error message. Tell IT which displays work and whether the problem affects the picture, sound, or both.