Lucas,
What is your goal for purchasing and analyzing this? Just curious.
Jack
The drive has arrived yesterday, I ordered a TB1H from First-Supply to have it fast (they deliver from the UK).
The one I received is a HY-DIV268N-5A wich looks exactly the same.
I couldn't wait to have a look at the inside and removed the cover.
The board is floating inside, it has no screws holding it in place. The chip is fixed to the heatsink and the board is held in place horizontally by the cover screws wich go through the holes but these have some play. See picture.
The chip pins experience all the mechanical stress when the plugs are installed or removed.
Next I removed the chip to have a look a the bottom side of the PCB. There's no thermal paste or pad..... and the mounting holes have some burrs, the chip will not make good contact with the heatsink.
Deburred the holes and remounted with thermal paste for testing.
I use a 33V supply, 4Amp Sanyo Denki bipolar motor and did set the drive at 2.5A and 1/8 microstepping.
The drive works but the stepping rate seems wrong, checked the swicth settings again .... Short story: the microstepping table is wrong, looks like 2 colums need to be swapped.
To be continued...
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Lucas,
What is your goal for purchasing and analyzing this? Just curious.
Jack
CNC is a hobby for me and designing stepper drives also.
I have a 30 years career in electronics repair and know where the weak points are, where they save $$'s using cheap components resulting in premature failures.
Good electrolytic capacitors and trimmers are expensive, my employees and me replaced several thousands of these, no kidding.
We had to give warranty after repair and for some models of computer terminals we simply changed approx 20 components to be sure they wouldn't come back.
Big problem is that a simple electrolytic capacitor fails and sometimes causes 10+ others components to blow at the same time, avalanche effect and thus an expensive repair due to a 2$ cent saving.
Back to the topic:
I have designed several THB6064 drives for me and MassMind.org, a TB6600 drive is coming soon.
For questions like the one below it's best to know exactly what the possible problems are with the cheap Ebay drives.
This is the reason I bought one to analyse and compare.
PS: I'm now working on the schematic of this drive and it looks like I bought a heatsink, some connectors and 2 optocouplers in a socket.
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There's a CD included with the drive, it has Mach3, some files for other products and a users manual for the drive.
Great: a Chinese Ebay product with documentation, maybe something positive?
But just noticed something today, see attached pictures and find the difference.
They are different and on top of that: neither of them is correct.
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I finalised the schematic and there are several things wich could be improved but these are not important.
Just one wich confirms the error in the microstepping table: look how the switches 5,4 and 6 are out of sequence with the M1,M2 and M3 inputs. They simply copied the microstepping table from the datasheet wich doesn't match the PCB layout and schematic.
The real error is in the circuitry for idle current reduction, the components wich define the delay are a 2K resistor and 1nF capacitor.
Their time constant is 2 µsec, this means that the drive will go into standby mode approx. 2µsec after receiving a step pulse.
Time to measure the effect of that.
Attached are 2 waveforms measured on the current sense resistors, one is from the Chinese drive the other from my TB6600 drive.
Drives are set for 1/8 usteps, 4 Amp and are driven at 30RPM.
Vertical scale is 0.2V/div. , 1 Amp on a 0.2 ohm resistor = 0.2V so 1 division =1 Amp.
Only the postive part is relevant, the negative part of the waves are a result of the decay mode.
The difference is clear, The wave form should reach 4 divisions for 4 Amp but the chinese waveform goes to 1.2 - 1.3 divisions with some hairy spikes.
These spikes are the 2µsec ones where the drive should reach maximum current after each step pulse.
What we are seeing here is a drive that basically runs in standby mode or 30% of the torque.
I'm thinking of an easy way to compare the torque, a weight attached to a lever seems the easiest.
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What is the horizontal scale timing set to?
A question about the waveform that I'm looking at - I think that you're differentially measuring instantaneous voltage across a series current-sense resistor to get the current through a single winding - on the screen shot for your driver it appears to me that we may be looking at multiple sweeps (perhaps four?) with a bit of triggering jitter, and not one sweep (whereas the shot of the Chinese driver looks like a double sweep). Otherwise I'm not sure that I understand the vertical overlap with offset of adjacent 'square' portions of the trace on the shot from your driver.
>>Only the positive part is relevant, the negative part of the waves are a result of the decay mode.
I'm a bit confused at that, because I would have thought that the negative part of the waveforms would have represented the bipolar nature of the driving. But then I have not previously looked at waveforms from a chopping bipolar microstepping drive. I'd appreciate any clarification of that point.
My assumption is that the width of each 'square' part of the trace is the duration between one step pulse arriving and the next as it holds a certain position and current level until it is advanced to the next microstep, and there is chopping (and decay) going on at each current level as it awaits the next step pulse which is represented by the height of eqch 'square' of the trace, and that if we were also simultaneously looking at the other winding's current we would see it out of phase with the first trace in order to handle the microstepping.
Horizontal is at 5msec/div.
I'll try to explain, English is not my maternal language and choice of words can cause misinterpretation.
This is the waveform at the current sense resistor for a single phase, not a series resistor.
There are indeed multiple sweeps overlapping each other, that's due to the automatic shutter timing of the camera in combination with the poor triggering of the scope, I also adjusted the intensity on the scope and that must have changed the shutter timing. They look better in real maybe a movie iso of picture would have been better.
The waveform is taken from the current sense resistors, if you have a detailed look at the current paths in the datasheet then the forward and reverse current through the motor both produce a positve half sinewave over these resistors and the decay currents generate the negative one.
Edit: you can also see some spots at zero current.
The TB6600 uses mixed decay, fast creates a negative current through the resistor and there's no current for slow decay.
That's entirely correct, if both windings would be visible there would be a sine/cosine waveform with a 90° phase shift.
The important thing here is that the chinese drive never reaches full current, you can see the "hairy" pulses after each step trying to get to full current.
But they don't due to the inductance of the coils.
Last edited by lucas; 07-22-2013 at 06:11 PM.
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Thanks for the clarification, that was most helpful.
For comparison here's the waveform capture across the sense resistor (0.226R) of the Haoyu driver.
Settings are 1/8 ustep, 30RPM or a step rate of 800Hz, 2A per phase, Vsupply = 24.5V.
In case you are wondering about the square yellow tiles - that's the current ramping up in the motor.
That's a nice shot, what equipment are you using?
800Hz is just on the limit when the TQ input could become low on that drive.(if my calculations are correct)
Could you measure it at 400Hz or lower?
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I was thinking of buying some of these drivers (hy-div268n). Do you think they will work well or should I steer clear?
When I searched for hy-div268n the first vendor to show up was Good Luck Buy. A bit of luck is certainly needed when buying a mystery product from the Far East. =)
They work but only at 30% of the chip's capacity.
A very simple torque comparison test did prove this, I have a short and crappy movie of the test setup wich I could post but don't have the time now.
A weight was attached on a lever fixed to motor axle, the HY drive could rotate 0.36Kg without loosing steps or stalling, my DIY drive worked up to 1.34Kg.........
Don't buy this one, it will never work up to expectations.
The Haoyu looks to be better but it will not provide full power at very low speed.
There might be some that work well but I haven't seen one yet.
Mine came from " first-supply " but the Paypal transfer confirmation showed " Xories " as the payment destination.
They all sell the same (crappy) product.
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Is the poor cooling the limiting factor?They work but only at 30% of the chip's capacity.
No, not at all.
The problem is in the design: wrong component values wich cause the chip to remain in idle current all the time wich is that 30%.
I think they never used a scope to verify their design, the concept isn't wrong but some component values are waaaaay off what they should be.
Also the designer didn't read the datasheet, there are at least 5 totally unnecessary components.
I did complain about the wrong documentation regarding the microstep settings, the manual and the drive's cover are different.
They were happy that I pointed that out and issued a partial refund but they are still on offer on Ebay with the same error.
It was already really hard to convince them on this obvious error and thus I didn't pursue the other problems like lack of torque.
They just don't care about the quality and performance: selling is important and if somebody complains, it takes 10 or more mails back and forth and if the customer doesn't give up then they just propose a partial refund: Issue closed and they continue selling the same crap.
The very same thing happened with the TB6560 drive's: Complaints, forum posts on the reliability issue, lack of and even wrong documentation in a lot of cases etc.. have no effect at all. ( see the posts on the forum here for TB6560 ).
Did they do something about this? No, not at all. The same stuff is still for sale on Ebay and other sources.
$$'s is the only thing that's matters.
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Well lucas, you seem to have the smarts to show us how to build a driver the right way. I know I would appreciate it if you would show us how it's done.
Are the TB6600 and the TB6064 the same?
Almost the same, differences are in the control signals and some features:
- different microstep possibilities, THB6064 has more.
- TB6600 lacks settings for decay modes.
- TB6600 has an internal 5V regulator but it's maximum current capability is not clear.
- TB6600 lacks automatic idle current and this is where the Chinese designs fail.
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