[lucas]

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.

Would one of the electronics experts on this thread compare the two stepper drivers below and tell me which is better and why. I am in the process of upgrading my CNC controller to discrete components.

Thanks

THB6064AH MassMind.org

CNC THB6064AH Two 2 Axis 64 Micro-step 4A Stepper Motor Driver MACH3 No Heat #A559A on eBay.

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.

[hollisin]

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.

Lucas,
Is it possible in the future you'll be analyzing and/or constructing some DSP-based drivers?
Jack

[bobgrant]

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.

[tholling55]

Do not assume that the schematic posted by Lucas matches your HY-DIV268-5A driver. There are multiple versions out there. Mine for instance has a different capacitor in the TOQ timing circuit. It is a 100 nF instead of the 1 nF in the schematic from Lucas. There are also other differences. The LED current limit resistors for the 6N137 are both labeled 560 ohms on mine, but they are actually 56 ohms. Please just note that the manufacturer has changed some of the design, and in other cases the board does not actually have what the component is labeled to be. The only way to be 100% sure is to measure it. I am a bit concerned that mine has 56 ohms, I would appreciate hearing back from others if they can measure those resistors.

Shorting out pins 3 to 4 can be detrimental for some machines. if you have the correct capacitor timing circuit that matches your machine it should be left alone. Shorting it out will lead to the drive being set at full torque at all times. For users with Linux CNC this can lead to excessive heat build up. The problem is that Linux CNC does not have a default setup for axis by axis enables. That would allow a motor to cool while not moving. In the default setting for Linux CNC all three motors will be pulling current, loading the power supply, and getting hotter until the machine is shut off killing the Amplifier Enable pin. If you have a scope you need to do exactly as Lucas did and verify the waveform across the current limit resistor. Watch for the spike indicating activation of the torque reduction. If this occurs during a step, the capacitor in that timing circuit needs to be increased. It is surface mount, but not that hard to replace. I
Good Luck.
Tommy

[lucas]

Do not assume that the schematic posted by Lucas matches your HY-DIV268-5A driver. There are multiple versions out there. Mine for instance has a different capacitor in the TOQ timing circuit. It is a 100 nF instead of the 1 nF in the schematic from Lucas. There are also other differences. The LED current limit resistors for the 6N137 are both labeled 560 ohms on mine, but they are actually 56 ohms. Please just note that the manufacturer has changed some of the design, and in other cases the board does not actually have what the component is labeled to be. The only way to be 100% sure is to measure it. I am a bit concerned that mine has 56 ohms, I would appreciate hearing back from others if they can measure those resistors.

I rechecked the schematic for those capacitor values and there's one 100 nF missing on the 5V line. There are only 2 1nF capacitors on the unit, both are in the torque reduction circuit, could you indicate wich one has another value on a picture or so?
Regarding the resistors for the 6N137: my mistake, they are 56 iso 560 ohm here also. This is to low, the led current would be 62mA and the datasheet mentions 50mA maximum. But I think that the optocouplers will survive this, a value of 270 to 680 would be best.

@ludovanginderen: I agree with most of what you are saying, some components will be hot so use a fan to cool the top of the PCB to extend their lifetime.
I only have one wich I bought to check it out, I won't use it :-)

Guys,
I worked out the problem with my TB6600 only driving at 30% current. The Clock Pulse is too short from Mach3 (1-5ms).

Solution is change the value of one of the caps to 1uF.

I'm afraid that this won't work for long. The transistor just below that capacitor has to discharge the capacitor wich is charged to 5V. There are no current limiting resistors or other features to reduce the discharge current. When the transistor is active it will short that 1µF capacitor and create a very high peak current, value could be something like 10A or more depending on the type of capacitor used. The transistor has a max current specification of 200mA, it will also limit the current but there are no specifications in the datasheet for this situation.
How long did you test this change?
Datasheet:
http://www.fairchildsemi.com/ds/2N/2N3904.pdf

[Arquibaldo]

Just a quick observation about post #63: as we all know, a resistor labelled 560 IS a 56 ohm resistor:
The final digit is the number of zeros after the first two digits; 0 means no zeros, so the value is 56 ohms...
A 560 ohm resistor would be labelled 561...

By the way, I also ordered one of these accursed drives on dec/2, before finding this thread... my bad...
I hope the info provided here by all the brilliant and dedicated people posting on this thread will
enable me to fix some of the design errors in this drive and recover a part of my (modest) investment...

Thanks a lot to you all, particularly the OP: Lucas.

Nelson

[tt-boy]

I cut a track and inserted a 100 ohm current limiting resistor before the 1uf cap and it seems to be OK. On that note I haven't got around to adding this resistor to my other machine and the modules are still working (haven't blown up yet)

[lucas]

Didn't have much time lately but didn't forget this thread.

I cut a track and inserted a 100 ohm current limiting resistor before the 1uf cap and it seems to be OK. On that note I haven't got around to adding this resistor to my other machine and the modules are still working (haven't blown up yet)

How long that it will work depends on your machine settings. The transistor has some work to do only at low speed.
If your start speed and acceleration is high enough then it has to work for a few pulses at the beginning of a move, after these initial pulses the transistor has an easy job doing almost nothing. If you want a "will always work" solution: test it with the machine running at 1-5 step pulses per second.

I did some measurements and it takes approx. 70msec for a stepper motor to stabilise after a single step.
The step pulse width is only 1µsec for some 3D printer firmware.
The entire torque circuit must respond within 1µsec and remain active for 70msec (preferable longer for safety reasons).
This is quite difficult to get right with simple circuits, even a retriggerable one shot has difficulties to operate within these margins.

I assume that if I want a kit (the one you designed) I go to MassMind and order it there. One question maybe you can help with, Can a kit be purchased (controllers and BOB) for 4 Axis, as Im thinking of driving the y axis with 2 motors (it runs the gantry, will be using linear rail system and ACME lead screws direct drive via motor). The machine will be about 24" x 24" max and used for PCB milling only, so I think smaller motors may work for me (once I figure that part out).

24" x 24" for PCB's only? That are large pcb's :-)
I would suggest to visit the "PCB milling" forum here, you will probably find very usefull info there.
Your setup is no problem, you can slave the 2 Y axis in software (Mach3 etc..) or connect the 2 drives to the same BOB output.
There are some differences between my BOB-drive setup compared with the Massmind one. Take a look and decide wich one suits you best.

Is there any information around when the Dir-Signal should be stable prior the positive edge of the clock (Step-Pulse) and how long it should stay stable (in relation to the positive or negative edge of the clock (Step-Pulse)?

I had a quick look at the latest datasheet and can't find it neither.
There are more spec's missing, like the max. output current that can be drawn from the internal 5V regulator.
On top of this they have changed some other parameters wich required some component changes in my design.

I have a design ready and it's in use on a Mach3 mill and 2 3D printers, all 3 are working fine. It will be released when I find some time to compile the documentation and update the website.

[lucas]

I can't receive private messages here on the zone for an unknow reason.

Project isn't dead.

PM sent to you.

[sea13]

Hi Lucas,

I tryed to contact you at the email indicated on your skynet.be webpage. Still in business with THB6064AH driver?

Cheers, Sebastian

[frie]

Lucas here is the link to the drive:
New 4 Axis TB6600HG Stepper Motor Driver Board Controller Demo Mach3 Software | eBay
Searching for drivers i found some that come with adjustable or fixed reduced current idle timing, some as late as 10seconds after the last pulse, could this be a solution for this board to stretch the timing?