©2018 NEC Display Solutions, Ltd. Page 59 of 7110 TroubleshootingProblem: No video when switching to the Compute Module inputSolutions:• Confirm the Compute Module and Compute Module Interface board are correctly installed.• On the COMPUTE MODULE menu of the OSD, confirm that POWER SUPPLY is set to ON.• On the COMPUTE MODULE menu of the OSD, confirm that USB BOOT MODE is set to DISABLE.Note: The Compute Module power will have to be cycled off and on after changing the bootmode to DISABLE.• Confirm that a valid OS image has been written to the Compute Module.Problem: Compute Module hangs at the rainbow screenSolutions:• The imaged OS may not include support for the Compute Module model being used.• Confirm that the image includes the correct corresponding file:• bcm2708-rpi-cm.dtb - for the Compute Module 1• bcm2710-rpi-cm3.dtb - for the Compute Module 3Confirm the Compute Problem: Screen appears gray and blacks aren’t true black.Solution:• Most OS distros on the Compute Module are set to output the video range of 16 to 235(otherwise known as “RGB limited”) by default.• Make sure the display settings for handling the video levels from the Compute Module matchthose on the OSD settings of the display. See the “Configuring the correct HDMI video levelencoding and decoding” section for more details.Problem: Black borders appear around the screen imageSolution:• Overscan needs to be disabled. Follow the previous instructions for checking the“disable_overscan=1” configuration setting in the config.txt file.
