@Daniel_Would
I made my own drives and only know about the manufactured ones through what I’ve read on the net, so I’ve no first hand experience I’m afraid. Although my experience does give me some insight into these manufactured boards. I know a lot more about what is wrong with them than even the people who originally designed them I think. That is not to say that they’re all bad, but there are parts that could stand for some improvements.
The absolute worst part about the manufactured boards seems to be the documentation that comes with them. I’ve read some of that online. Knowing what I know, and comparing it to what they say there are gaps in places. My advise there is to get Toshiba’s original documentation and learn that yourself. No one knows that drive IC better than Toshiba does.
The biggest issue with any manufactured TB6560 drive board is with the current sense resistors and how adjusting the output current is handled. The sad fact is there is no easy way to adjust that current because of how Toshiba designed the chip. They designed that chip to be put into custom builds. Something like a VCR where the designer knew exactly what motor it was going to be driving etc. When that is the case everything is rosy, unfortunately with hobby CNC things get muddy.
These drive board manufacturers have taken it upon themselves to outfit their boards with sense resistors then tell their customers to adjust current using the digital input lines. That quite frankly is a crock of crap they’re peddling there. It works but it is less than ideal. Toshiba put those lines on the IC for software motor control, not to adjust the overall current.
I annotated this image in red to highlight the current sense resistors
Note the manufacturers annotation in the neighborhood of the fan on the heat sink “Operating current sub - setting” That is a fabrication on their part. Yes it will adjust output current in crude quarter steps but it isn’t what any CNC builder really wants. Better to leave that at 100% and just have the right sense resistors installed. Toshiba’s documentation explains how to calculate the correct value for your motors.
But for what they are the multi axis imported boards are pretty impressive never the less. It just takes understanding what they really are, as opposed to what the manufacturers are saying in order to realize their full potential. The key is in due diligence on the part of the integrator. I’ve read many horror stories online where people didn’t fully appreciate their responsibility in the equation.
They could make a Fox show about all of this, When Good Drive ICs Go Bad. The moral of course is the ICs are good, the boards are even pretty good, it is people who are bad. The people making those boards, and lots of the people using them too. What I’m saying is if you do your part you can salvage this situation to your benefit.
And yeah, looking at that board it is fully optically isolated too. You can see the 4 leg DIP ICs on the left hand side of the board. Those are all single channel optocouplers. Although how the board handles crosstalk between the drives on the board itself I’ve no idea. I imagine it does though. They’ve cunningly placed electrolytic capacitors around it I suppose by the looks of things. Even on the output side. Interesting.
