eBay TB6560 Stepper Motor Driver Boards

[on7mi]

Hi to everybody,
I am using two off these boards on my cnc machines for two years and have no problems whit these,but Iam a hobbyist no a pro.
Thes boards are very cheap instead they are sold for 140 Euros in Germay.I bought them in China for minus of 50 Euros.
At this price you can budget a reserve one in case off!

See you
Mike

[Tenson]

I've got one of these boards running my CNC3040.

I'm curious because it is running on 24V and gets nothing like hot, but it sounds like most here find they get rather warm. I think I could even run mine without the fan!

It also doesn't go very fast - I can get a reliable 1200mm/min from it. I did run it at 1900mm/min but found it occasionally skipped steps.

Is this normal? Have I got something set-up wrong?

The stepper motor shows about 2 Ohms across each of the connections to the board. I don't know if this means it is in parallel or series as the connections at the motor end are covered by heat-shrink.

The big resistors near the output (I assume current sense) are 0.4 Ohms.

Measuring across one of these I get 200mV on idle and 280mV at full speed. That is about 0.7A, so does this means the motor is drawing 1.4A because it is each phase? You can see the measurements below.

This is at idle. The time base is 50us/Div


This is at full speed, but please note the time base is now 10ms/Div

[Jonathan]

On the 'idle' graph I make it 12% duty cycle. So since current is 0.5A peak, that makes it:
0.5*0.12=60mA average
0.5*0.12^0.5=173mA RMS.

Can't really find anything useful from the other graph - it just shows how at that speed the current is limited by the inductance of the motor. I guess we could calculate the motor inductance ... T=2.07ms, change in current is 700mA, so dI/dt=700/2.07=1.449A/s (linear approximation).. applied voltage is 24V minus a bit for losses so call it 23V, so the inductance L=24/1.449=15.9mH (roughly, oversimplifying a bit there). That's either a pathetic motor or I've done something wrong! Unless it's wired in bipolar series, that would be reasonable since the same motor in bipolar parallel would be about 3mH which is not bad.

Either way these numbers seem a bit fishy.. please could you link to the motors you are using (datasheet?) and confirm that the resistor you're measuring across is definately 0.4ohms, not two 0.4 ohm resistors in parallel or something like that.

The simple answer is just increase the current and so long as the motors don't get too hot, i.e. above 80°C on the case, it's fine.

[Tenson]

Hi,

The motors don't get hot at all, and neither does the driver board.

I don't know what motors they are, they are no doubt pathetic as they come with the CNC3040 and are small.

I stuck my LCR meter across one of the connection to the board. It tells me 1.93mH at 15KHz and gives 1.4R DC resistance.

I stripped back the wires at the motor end. There are actually 6 wires coming out, 2 of which are not connected at all, and the other 4 go to the board, so it seems I don't have any choice about series or parallel.

The resistors seem to be one per phase and are 0.25R. I thought it was 0.4R because the meter probes have a small series resistance.





Oh and the dip switches are set like this:

[russell]

The 0.25 ohm resistors should give you 2 A maximum. Your DIP switches are set for 75% current so that gives 1.5 A - not far from your measured 1.4.

You should be able to identify your motor from this data sheet:

[Tenson]

I doesn't seem to be any of those! Body length is 53mm, phase resistance is 1.4R and phase inductance is 1.9mH.

I found that when I set the current limit switch to 100% it ran worse.

I could increase the voltage to the board. The motors nor board run hot. Is it safe to do so, and should I make that mod listed earlier - http://www.mycncuk.com/forums/showth...ll=1#post19305

[russell]

Did you measure the body length including the boss? If so it should be 51 mm and is probably a 57BYGH51-602A and produces 100 oz.in (about 0.7 N.m) at 2 A. Your resistance and inductance figure aren't a mile off considering the quoted tolerances.

I know the voltage rating is higher than 24 V but, considering the reliability (or lack of it) of these boards I would be nervous of doing so. Some of the mods suggested on various sites are decidedly dodgy!

Russell.

[Tenson]

Did you measure the body length including the boss?

Russell.

Nope, excluding like the diagram.

[russell]

Just measured my motors which are the 76 mm type and they measure 77.6mm so I still think you have the 57BYGH51-602A type.

Your waveforms look strange to me. The voltage across the current sense resistors should go between 0.5 V and - 0.5 V at 100% torque or 0.375 V at your 75% setting. Is the earth on your oscilloscope properly isolated from the board? If I remember rightly the isolators on these boards only isolate the signal lines not the earth. Are all three outputs the same?

Russell.

[russell]

Doh - I think I must have had a senior moment last night! I was assuming that the current sense resistors were in series with the motor but of course they are the other side of the output bridge so the current is unidirectional there thus it should be going from 0 to 0.375 V.

Still the waveforms don't look right to me. I can't check on my board as I no longer have access to an oscilloscope but according to the data sheet the motor current waveforms should look like this:

The waveform across the current sense resistors will of course be rectified.

Hope that helps.

Russell.