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Clevertouch & interactive screensMedium2 min read

HDMI keeps dropping, or says No signal after a laptop wakes up

Please note: this is independent guidance. Vision Tech is not affiliated with Clevertouch. Menus and features differ between models and software versions, so check your screen's own manual or on-screen help, and speak to your school IT team or supplier before changing admin-locked settings, updating firmware or doing a factory reset.

You connect your laptop, the picture appears, then it disappears or flashes. Or the screen worked before the laptop slept and now says there is no signal. These are common and usually solved by simple checks.

Check the cable first

  1. Push both ends of the HDMI cable firmly into place.
  2. Look for bent pins or a damaged cable.
  3. Try another HDMI cable, preferably a short, good quality one that supports 4K.
  4. Avoid cheap adapters and long extension leads if you can.

A loose cable that is moved slightly can cause dropouts, so avoid tight bends or hanging weight.

Check the source

Make sure the panel is set to the input you plugged into. Some screens switch automatically and then switch back. If you see no signal, open the source menu and choose the right input.

After the laptop wakes up

Laptops sometimes forget the external screen when they sleep.

  1. Wake the laptop fully and wait a few seconds.
  2. On Windows, press Windows key + P and choose Duplicate again.
  3. If this does not work, unplug the HDMI cable, wait, and plug it back in.
  4. As a last step, restart the laptop with the cable connected.

You can also stop the problem coming back by changing your power settings so your laptop does not sleep during a lesson or meeting.

Check the display settings

A very high resolution or refresh rate can overload a cable. Try lowering the refresh rate in the laptop's advanced display settings.

Docking stations and adapters

Docks, USB-C adapters and splitters can all cause dropouts. Try connecting directly to see if the problem goes away.

Make it more reliable

  • Leave the cable connected to the screen for the whole day.
  • Keep a spare cable in the room.
  • Turn off sleep and screen saver during lessons.

When to get more help

Ask IT if it happens with several laptops, with new cables, or in the same room each time. Note how often it happens and whether the screen's own home screen is steady.

Did this help? If you are still stuck, email Vision Tech and tell us what you can see on the screen. Menus and button names can differ slightly between versions and makes. If something does not match, stop and ask rather than guess.

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