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Fixing Shapeoko 3 Disconnect Issues

Anyone who has purchased a Shapeoko 3 from Carbide 3D will have experienced or heard about the disconnect issues that some machines are having. This issue involves the Shapeoko stopping and loosing serial connection with its controlling computer. From what I understand it is caused byt the Grbl board being suceptible to noise and fluctuations in its 24V power supply. These can often be cause by noisy mains appliances on the same circuit as the one your machine is plugged into.

I have experienced these issues with my machine and have taken 2 main steps to solve them:

When I first started having these issues, I went to the Carbide 3D forum and came back with a simple solution of electrically linking all the metal parts of the Shpeoko (including the metal casing of the Dewalt trim router) to earth (ground).

The effects were immediate and I could now use my 2KW (electrically noisy) vacuum whilst the machine was running without experiencing any disconnects.

But there were still other electrical items in my workshop causing Shapeoko disconnects so on to step 2:

I had researched that adding a 1500uF capacitor (50v) across the 24v rails could help smooth out the power. So I bought one and got started installing it:


Firstly, I removed the 4 screws that hold the PCB onto the big aluminium heatsync.


I then carefully removed the board as the thermal paste is quite sticky and it is best not to put to much strain on the board by pulling it off.




The thermal paste could then be cleaned off using some 99% Isopropanol ready for re-application when I re-attach the board to the heatsync. The yellow tape is kaptopn tape and electrically insulates the back of the PCB from the heatsync.


This is the beefy capacitor I selected: 1500uF 50V


I soldered some wires onto the terminals and then slid some heatshrink over to prevent any shorts.


I then soldered the capacitor to the board making sure to get the polarity right. There is a negative mark silkscreened on the front of the bard so you know the right orientation (negative to negative, positive to positive).


Thermal compound can be re-applied and then the board can be re-attached to the heatsync and that’s it! I will do a follow up on this to explain how well this mod has worked!




  1. AJ AJ

    How well has this worked?

    • Nick Nick

      I haven’t had a disconnect caused by the spindle since. The only thing that triggers it is if I have my belt sander connected t the same power outlet…

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