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.