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the_digital_dentist
A SmoothieBoard has the pins for external driver connections (as do a few other boards that cost a little more).
So does the Duet 0.8.5, which costs somewhat less - and you can use 4 external drivers as well as the 5 on-board drivers. So in a large 3D printer you can use external drivers for the XYZ axes and the internal drivers for exrtruders.
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the_digital_dentist
The driver in your photo looks like one of the problematic TB6600 units. I suggest you look into it
DD, can you elaborate - what are the problems?