I finally decided to replace the MKS Sbase board in installed in my K40 last year with a version 1.x 5 channel smoothie board sourced from eBay a month or so ago.
I am waiting for the version 2 board I signed up for as part of the kick starter to show up, but I bet the “virus” has put a dent in the schedule on that being released.
Change over went very will, little to change other than the connector ends for the limit switches and to add a 5V power supply to power the RepRap discount display that was installed in the machine last year.
Problem is, about 50% of the time when powered up the smoothie will not start and I get a continuous tone from the display board.
Looking at the LED’s I have Red/Red/Grn/Grn/Grn/Grn ( all are on solid )
If i press the reset the board will come alive and run. Once up and running the laser works flawlessly. Powering it down and waiting until the power LED on the board goes out it will start with the same percentage of chance.
I am pretty convinced it is a power supply issue, but before I order the specified 5V regulator and eliminate the separate power supply, I figured I would through the question out here.