YRC1000 ALARM CODE 4109 DC 24V POWER SUPPLY FAILURE (I/O)

Most Common Issue: Blown Fuse caused by short in I/O wiring or I/O device.

In the case of a YRC1000 without external 24VDC supply, the robot controller generates the 24VDC.  This is protected by a fuse which is mounted on a YIO circuit board.  This photo that follows shows the location of the fuse, when the fuse is functioning properly, the LED shows green.