Common Issues and How to Fix Them on Your CommBox Classic S4

Applies To

Applies to: Classic S4, Classic S4+

Lock Screen or Settings PIN Forgotten

Issue: You’ve forgotten the lock screen or settings PIN
Solution:

• Read this article first - What to do if you don't know the PIN

• If still stuck Contact CommBox Support at +61 2 9975 6001 for assistance

Wi-Fi Issues (5 GHz Not Connecting)

Issue: The CommBox can't connect to a 5 GHz Wi-Fi network
Solutions:

• The Wi-Fi module may not be installed correctly—check that it's securely connected underneath the screen

• Some 5 GHz bands may not be supported—ask your IT administrator to review the network settings

💡 Note: 5 GHz has shorter range and may be blocked by walls or large metal objects. Try a 2.4 GHz network instead.

Stylus Missing or Damaged

Issue: A stylus pen is broken or lost
Solution:

• Order new Stylus online at Karter.

Missing or Unavailable Apps

Issue: An app isn’t showing or can’t be installed
Solutions:

• The app may not be able to run on Android 11.

• Note: Apps requiring Google Play Services (e.g. Google Play Store) are not supported

The CommBox Won’t Turn On

No Status Light

• Check that the power cable is firmly plugged in

• If using a power board, ensure it’s switched on

• Make sure the main power switch (next to the AC inlet) is set to the “I” (on) position

• Test the power outlet with another device

• Try a different power cable if available

Red Light On, But Screen is Blank

• Press the Power button on the screen or remote

Green Light On, But Screen is Blank

• Wait 30 seconds after powering on

• Disconnect anything plugged into HDMI OUT ports

• Restart the CommBox

The CommBox Turns Off Unexpectedly

Issue: The screen powers down or enters standby too soon
Solutions:

• Check the power-off timer in Settings

• Review the auto no-signal power-saving setting

• If connected via RS-232 (e.g. room control system), temporarily disconnect it and test again

Screen Display Problems

Blank Screen (Green Light On)

• Ensure connected computers are powered on and not in standby

• Restart both the CommBox and the computer

• Try different video cables

• Check that the computer is outputting a supported resolution (recommended: 3840×2160 or 1920×1080)

• Ensure the computer's external display port is enabled

“No Signal” Message

• Confirm the computer is connected to the correct input

• Make sure the input source selected on the CommBox matches the port used

• Enable external display output on your laptop

• Use only CommBox-recommended video cables

Distorted, Flickering, or Dim Image

• Switch to another input, then switch back

• Restart the CommBox and any connected devices

• Confirm the resolution and refresh rate on your computer match supported settings

• Replace or test with new video cables

• If these tips do not resolve it - contact CommBox Support.

Bright Spots or Colour Issues

• Try adjusting the image mode in Settings > Image

• Small colour variation is normal between side-by-side displays

• If using VGA, test with another cable or source

• If these tips do not resolve it - contact CommBox Support.
  
  

Image Shifted or Cropped

• Adjust video output settings on your computer (zoom, crop, overscan)

• Use a darker background instead of black

• If using multiple monitors, try duplicating the display or setting the CommBox as the only screen

Image Doesn't Fill the Screen

• Adjust the overscan or scaling settings on the connected device

• Make sure the output resolution is supported by the CommBox

No Video from USB-C

• Confirm the device supports CommBox Port Alternate Mode via USB-C

• Look for the Thunderbolt logo—if missing, full video+touch may not be supported

• Use a cable marked for SuperSpeed (5 Gbps or higher) with the USB logo

• Replace the cable if not compliant

Still Need Help?

📩 Log a support ticket or call +61 2 9975 6001. If you want faster support remember to provide video or photographic evidence of the issue.