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DQ542MA Stepper Driver: Garbage Reliability So Far

Discussion in 'CNC Mills/Routers' started by Kevon Ritter, Oct 26, 2017.

  1. Kevon Ritter

    Kevon Ritter Veteran
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    My machine has been running for about 4 months. One driver was DOA. Today, another may have bitten the dust...in the middle of a job. That's a 60% success rate in less than half of a year.

    I start up for the first time of the day. I try to home and the A axis isn't moving. All of my signals are fine. The wiring is intact. There is no dust or foreign objects anywhere. The steeper works fine on any other channel. Any other stepper fails on the A channel. Instead of being locked, the connected stepper can now be rotated by hand. It does not rotate as easily as a completely disconnected stepper, but it still rotates.

    So tell me, is this normal?

    Oh and my green led is out on that driver alone.
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    Did you check the fuse?
     
  3. Kevon Ritter

    Kevon Ritter Veteran
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    I didn't even know they had fuses. Thank you my good sir. Sure enough, the fuses on both dead drivers are blown. Now the question is why? Both would have blown during the power up phase which is 24V. They are rated for 18-50V.

    Looking at the bright side, if this fixes both of them, I'll only need one more to build another machine. :p I do apologize for this thread as a whole.

    After looking for the fuse, I did notice that they are only rated for 32VDC. I can't find the stupid thing anywhere though. I may just hardwire a regular fuse in place.

    I actually already have another one on order, but if I can fix this asap, then I could be running over the weekend.

    (It's the white box looking smd to the top right.)
     

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  4. Kevon Ritter

    Kevon Ritter Veteran
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    So I tried this out. The result was a small pop and that little cloud in the picture. If the old one is blown, then wiring in parallel won't make a difference as there is only one path for current to take.

    Now I'm scared to try the second one.
     

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  5. Joe Santarsiero

    Joe Santarsiero OB addict
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    That's interesting. So you put a blade fuse inline. Did it blow the fuse? It's hard to tell from the 1st image. I'm guessing it did(I wouldn't expect the smoke where it was).

    My uneducated guess on the problem is that one of the transistors on the back of the board is shorted(bad and stuck maybe) and supply is being shorted when power is supplied.
    No offense, but did you ever hook them up reversed? I would think they have reverse polarity protection, I see a few diodes on the bottom front, but I'm not sure that's what those are for(maybe ICs could help against this too I guess). It's hard to find board schematics!
    Try the other drive the same way. If you have a meter then check the onboard fuse first.

    There are a lot of these drives in circulation and they seem to have mostly good feed back because they're generally reliable and have great performance. I'm now curious to know if you hit the lotto or made a booboo. ;) It's possible there's a bad batch in circulation too.

    If yours are going for the trash or are going to collect dust on your bench then I might take the failed drives off of your hands for the cost of shipping. I don't have any winter challenges(and I hate the cold). Let me know. On a limb, you could also try to contact wantai directly.

    Maybe a guru will chime into point you in the right direction or some web sleuthing will be fruitful.

    Regardless, keep us posted.

    Joe.
     
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  6. Kevon Ritter

    Kevon Ritter Veteran
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    The blade fuse did not blow.
    It has never been through a reverse polarity situation.
    I figured it was something on the other side of the board that blew as well, but haven't taken it apart to check.
    I may have switched them, but I'm 99.999% I tried the one that was working without issue before.
    It is likely that the replacement came from the same batch as the original DOA.

    Thanks for the tips and suggestions. I'll give the other one a shot in the morning...er when I wake up. And I definitely don't mind sending the board(s) your way, but the heat sinks are mine!!! They should work well for a compact aquarium light. :D

    Kev
     
  7. Kevon Ritter

    Kevon Ritter Veteran
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    Same result with the second.

    The fuses aren't blowing. I checked the underside of the board. My sniffer doesn't detect anything burnt on the bottom. Looking at the top reveals a different story. There is a 50ohm resistor next to the fuse. That resistor (on both boards) does not look like all of the other same format resistors (varying ohm range). It also seems to be in the same general spot as the tiny spark I'm seeing.

    Look at the bottom left for the burnt 50ohm. Look to the top middle for the 20ohm.
     

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