I've seen a few posts regarding the Wantai (Changzhou Wantai Electrical Appliance Co. Ltd.) DQ860MA stepper drivers, asking about wiring and such. They're part of some of the stepper motor kits Wantai sells on Ebay, and don't come with data sheets.

Some information I came across that is entirely in German can be found here:
http://www.joker-technik.de/media//D...3effffffef.pdf

I'm now the proud owner of three of these things, as part of a kit I bought from Wantai for a 3-axis mill build I'm working on. I've done a bit of research, and hopefully what I found will be helpful to others.

The DQ860MA may be rebranded/OEM devices manufactured by Leadshine Technology Ltd., also out of China (Leadshine Technology - Home). The PC board in the driver says "m860a", which isn't a model sold anywhere, from what I can find, though the numbering scheme is consistent with Leadshine's. Also, the DQ860MA seems to be sold through a number of outlets and under various brand names and even different model numbers.

Leadshine manufactures and sells a range of stepper drivers, including some with basically the same specs and appearance. The closest is the M880A:

http://www.leadshine.com/UploadFile/Down/M880Am.pdf

One difference between this datasheet and the information Wantai provides for this item is the value of the input resistor: the datasheet says 270 Ohm, and Wantai says both 270 Ohm and 200 Ohm. In fact, at least for my drivers, the input uses 220 Ohm resistors.

The Leadshine datasheet points out that there are jumpers that allow additional pulse settings on the internal driver circuit board. After opening the driver up, I can see they are really there, though I would guess most users probably won't need to change these, I'd imagine, for use with Mach3 or LinuxCNC.

The datasheet also provides good information on thermal considerations and mounting of the drivers, and information on protection functions.

Leadshine is a company that appears to have solid American connections, and indeed, looking at the driver's internals, they use quality parts by ST Microelectronics, Sharp, Fairchild Semiconductor and others. There's also at least one unmarked chip that looks like it's probably an ASIC. The printed circuit board is professionally made (2-layer, I believe) and coated, and the part placement and soldering is obviously done by machine.

On the other hand, the "JH" electrolytic capacitors used throughout (Jianghai, a Chinese brand) have a mixed track record, especially if exposed to excessive heat. In fairness, they're used in a lot of consumer electronics made elsewhere, not just in China (e.g. APC UPS's), and many brands of electrolytics have had problems over the last decade.

The input optocouplers are two types. The optocoupler on the "enable" input is a Sharp PC817. This is a relatively slow optocoupler (of the same variety as used in the Wantai break-out-board for all signal paths), and the "enable" input is obviously not designed for rapid input changes.

ftp://ftp.elektroda.net/pub/Karty%20...we/pc817xx.pdf

On the "pulse" and "direction" inputs, by contrast, the driver uses a Fairchild Semiconductor HCPL-2531 dual optocoupler device:

http://www.fairchildsemi.com/ds/6N/6N136.pdf

These parts are much faster, and allow the drivers to work with Wantai's specified pulse widths of 2.5 microseconds or longer (the M880A datasheet actually says 1.5 microsecond, which the optocouplers, at least, should typically support).

Wantai's bread-out-board, I suspect, and the slow optocouplers on it, is the cause of some difficulties users have had with Wantai kits--type 817's are simple devices that aren't designed to be fast, and the slow rise and fall times of the Everlight EL817's on the output of all signal paths would probably lead to smeared pulses and minimum pulse widths of 5-10 microseconds or longer. The good news is the output optocouplers on the BOB can be bypassed, as the DQ860MA already provides isolation from the motors with its input optocouplers. If the BOB optos are bypassed, though, it will result in inverted pulses going from the BOB to the driver which need to be taken into account.

Alternatively, a different break-out board that uses faster components would work, too, as long as power supply and signal voltage level recommendations are observed.

In summary, the drivers appear, overall, to be of good quality. The only potential issues I see, at least after a quick look-over, are the caps and whether enough thermal paste is used between the driver transistors and the heat sink.

I wasn't able to see the make and model of the driver transistors, nor did I map out the circuit schematic overall.