eBay TB6560 Stepper Motor Driver Boards

[ccmarco]

Maybe someone could be interested about the way i modified ground path around TB6560s in my 3 axis board, blue PCB.

Here is the link to italian forum where i published same photos : http://www.cncitalia.net/forum/viewt...26754&start=10

I also changed Fosc capacitor (pin 7 to ground) from 1nF to 100pF and, in conjuntion to step lines optocouplers bypass, now the board works flawlessy with Fstep of 50Khz.

Yes, i know, datasheet reports 15Khz max ...

But i don't mind about that.

Marco.

[irving2008]

Interesting Marco... did I understand you bypassed the optocouplers? That would increase the step rates, the optocouplers they use are fairly low-spec. Personally I would have looked at replacing them with higher spec devices and retained the isolation.

[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.

[geekinesis]

Hi
I have the 3.5 amp version of the board. The limit resistors are .15 ohm on mine. If I wanted to run .4 amp motors, what should I change the resistors to to.

I have .33 ohm resistors so was hoping to use them, but my maths isnt good with amp v etc

also is it ok to just change the resistors? As I understand the 2.5a boards are the same but with different resistors?

[dandumit]

From datasheet :
Iout(A)=0.5V/RNF(Ω)

Result : I out = 0.5V/0.15 Ohm = 3.33(3)

From datasheet tb6560 has the maximum of peak at 3.5 A.

[geekinesis]

ah great, thats what I was looking for.

So .33 ohm gives me 1.51, perfect

Also I have a 1.2A 3.8v stepper. Is there any harm in running it at 1.51A?

[dandumit]

always have a look on datasheet of component.
also please take note that I have seen on many Chinese boards that the dip switches settings are described wrong.

[gorbo]

I am using one of these boards with no problem what's so ever, mind i do have a 120mm blasting cold air on it, I have it running for 6 hours non stop, I do find the steppers get very hot is this normal?

[gorbo]

I am using one of these boards with no problem what's so ever, mind i do have a 120mm fan blasting cold air on it, I have had it running for 6 hours non stop, I do find the steppers get very hot, is this normal?

[Jonathan]

I am using one of these boards with no problem what's so ever, mind i do have a 120mm fan blasting cold air on it, I have had it running for 6 hours non stop, I do find the steppers get very hot, is this normal?

Depends how hot is very hot! 80°C on the motor surface is OK. If it's too hot then turn the current down a little. You won't need to turn it down much since power is proportional to current squared....