eBay TB6560 Stepper Motor Driver Boards

[ccmarco]

Hi Irving,

the power section of these cards is not galvanically insulated from parallel port connection, both share same ground.

Here, optocoupling gives only a partial safety gain, because a lot of current could flow through PC ground.

So we have a "half way" protection, capable only to break direct reflow of high voltage supply on parallel port lines.

Placing high speed optocouplers, like 6N137, is not simple because they do not have same pinout.

So i simply bypassed step lines optocouplers with 270 ohms res., in future i will place zener diodes (or transzorbs) on HC14 side and i will change resistors with higher value ones, to eliminate the high voltage reflow risk.

I have to say that the full modded board behaves good, but the fix was a sort of personal challenge

Marco.