Problem description:

The machine cannot recognize the U-disk, and LCD panel show no U-File when you choose Read U-disk file. 

Possible Reasons:

1. The U disk type

The U disk can be recognized by machine:

Disk Max capacity：16Gb（including 16Gb and below）

The U-disk interface protocol is 2.0 

Note: How to judge the protocol of U disk

Insert the USB in the PC/laptop , check in the device manager of the system and check USB port, it will show USB2.0/USB3.0 

USB2.0 have four pins, two for power, one pair for data.

USB slot which contains black-USB2.0

Solution:

Change to a  USB 2.0 U-disk for testing. 

2. The file format is incorrect

-The file on the USB stick must be exported by RDWorks/Lightburn/Lasermaker of type .rd. It is not the same as the project file. Please check if you saved the file correctly.

Solution:

Please save the file with correct way. A video is for reference.

Using U-Disk With Thunder And LightBurn - YouTube

3. The U-disk is faulty

Solution:

Please replace a new U-disk for testing.

4. The U-disk port on the outside is faulty

If the U-disk and file format are all good, maybe the U-disk on the outside is faulty.

Solution:

Please plug the U-disk to the U-disk port of the controller board ( Open the left door you can see it), see below picture.

If it’s working after you plug the U-disk in the controller board, it maybe the U-disk port of the left side is faulty. 

5. Too Many RD files on the U-disk, Odd Symbols or File Names too long

6. Files not Saved to Root\Main Directory