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I think I fried something?

Ivan Nair
2018-07-15
2018-07-25
  • Ivan Nair

    Ivan Nair - 2018-07-15

    Help! This is my first arduino project and I connected everything, got the arduino files uploaded to the board. Yay!

    I plugged in the DC power and tried to adjust the mA to 245. While doing so, the board beeped 2 or 3 times and now it won't power back on.. what have i done?? everything is soldered on so it would be a huge pain to take it apart. Is there a way to restore it?

    Also, I can still connect to the nano and it appears to connect to the myFocuserPro software but the motor doesn't do anything.

    When I plug it in only the red led comes on now and no beeps.

     

    Last edit: Ivan Nair 2018-07-15
  • brownrb

    brownrb - 2018-07-16

    Did you watch the videos?
    https://www.youtube.com/watch?v=3TIrv_IkQuY
    We recommend using the manual method. What probably happened is your connection from the drv8825 to meter to stepper got broken whilst trying to adjust current and you blew something on the board, probably the drv8825.

    Step1:
    Try to reprogram the board with the same v273 firmware. If you can reprogram the board then the nano is probably good.
    If you cannot reprogram the nano then start over with a new board as the nano is shot

    Step2
    If you can reprogram the nano,
    1. make sure everything is off
    2. connect the stepper
    3. apply 12v
    4. connect nano to computer via usb
    5. try the manual method (watch video) for adjusting the current.
    6. If the motor does not move no matter what then the drv8825 is shot

    There are big warnongs - do not disconnect stepper motor when power is on - this can easily happen trying to adjust using current - and I suspect this is what happened

    Regards
    Robert

     
  • Ivan Nair

    Ivan Nair - 2018-07-16

    Hi Robert,

    Thanks for the quick response. Unfortunatley I tried the adjustment without watching the video before doing so. I was actually following a different tutorial, it was helpful but he did adjust it with a screwdriver and thats where I think I messed mine up.

    Fortunately, I was able to reprogram the nano and followed the steps above but the motor didn't move and it looks like the drv8825 is dead. And to top it off its carcass remains firmly attached to the board via my less than stellar solder job. I tried a wick and the solder sucker but its not good enough to loosen it. I'm ordered some chip quick and hopefully that'll do the job.

    If all else fails I have one last board left, I kinda jump into projects and then troubleshoot from there, I'm quickly learning with soldering thats not a great idea.

    Thanks again for your help!

     
  • brownrb

    brownrb - 2018-07-16

    Hi Ivan
    What you could do is use a fine pair of sidecutters and snip the pins of the drv8825 where they meet the pastic of the ic chip. The chip then comes off leaving the pins behind. Then you can solder the new chip onto the left over pins - just use a good 40W (no more) solder iron with fine tip and do not apply too much heat - solder pins quickly and it should be ok.

    Regards
    Robert

     
  • Ivan Nair

    Ivan Nair - 2018-07-20

    Hi Robert,

    I finally got around to removing the drv 8825 by snipping off the old pins, and I orderd a new 5 pack of them (just in case!) I resolderded the new one on and followed the instructions above and the video.

    It is showing 0 on the current and the stepper motor does not move at all. I can connect to the myfocuserpro software like before but I don't seem to be getting any power from the 12V. Could any of the other components have been fried and should I replace anything else in addition to the DRV8825 and if so, which ones?

     
  • brownrb

    brownrb - 2018-07-21

    Ok, what ever you do please do not try and measure the stepper coil current.

    With 12V connected - does the nano led light up when power on? Does the buzzer and leds give a small blip when power is turned on? If so the power is getting to the nano. If not yoy would need to trace backward. Check VIN - should be 8V, check the LM7808 out pin - should be 8V, the LM7808 in pin should be 10-11V.

    From the 12V in, check each side of the diode, one side should be 12V the other 10-11V, If one side is 12V and the other 0 then the diode is kaput.

    Check J11 - each side should be about 10-11V, if one side is 10-11 and the other is 0 then the fuse is blown.

    Check VMOT of the DRV8825 - should be about 12V.

     
  • Ivan Nair

    Ivan Nair - 2018-07-22

    Hi Robert,

    I think it was the LM7808, I removed it and resoldered a new one on. I am now able to get power to the nano and could connect everything up. However I'm still getting issues with trying to adjust the current on the DRV8825. I am attempting this manually but the stepper motor moves only on slow and is pretty jerky. It also barely completes half a revolution even with 5000 steps.

    On the multimeter the reading is either 0.31 a or .07a or 0a and I don't really see anything in between. at 0.07 it doesn't move at all and just buzzes. I carefully turn it slowly so it starts turning but it jumps to 0.31a and doesn't budge from there. at that current it does what I described above.

    Is something else not connected right?

     

    Last edit: Ivan Nair 2018-07-23
  • brownrb

    brownrb - 2018-07-23

    You have not said what stepper you are using?

    Are you sure its wired correctly - with coil pair 1 going to A+ and A- and coil pair two going to B+ and B-

    You can test the pairs using a multimeter - each correct pair will have low resistance.

    You are getting about 12V on VMOT of the DRV8825?

    Forget about voltage and current measurements - it will not mean much and is not a good rule as so many people use so many different steppers and it varies for each one.

    You also did not say what firmware file you are using?

     
  • Ivan Nair

    Ivan Nair - 2018-07-23

    Hi Robert,

    I'm using the Nema 17PG27 stepper from omc-stepperonline.com . I checked the voltage on the DRV8825 and got 12 v or 11.45v to be exact across VMOT . Also I'm using firmware v2.73.

    I think I it may be the wiring that is incorrect, I'm away from my station right now and I'll check it again but based on the stepper, do you know the order of the wire colors? i'm using the aisler PCB Rev 1.2.

     
  • brownrb

    brownrb - 2018-07-23

    should be
    red - rs232 pin 4 - drv8825 2B
    blue - rs232 pin 3 - drv8825 2A
    green - rs232 pin 1 - drv8825 1A
    black - rs232 pin 2 - drv8825 1B

     
  • Ivan Nair

    Ivan Nair - 2018-07-23

    Hi Robert,

    Thanks, I was following the Schematic for the DRV 8825 Hw203 Full which had a different variation. The wiring arrangement above worked for me and now the motor turns smoothly, However now I'm not seeing the motor change direction whether i'm stepping up or down, it only moves anti-clockwise. I tried switching each pair (red with blue) and that only made it turn clockwise instead in both directions.

     
  • brownrb

    brownrb - 2018-07-24

    Ok, so the pairs are green/black and blue/red.
    What I would do is set to above. Then test.
    Then power off
    Swap red and blue over
    Power on then test again
    Power off
    Then set back to above
    Then swap green black over
    Power on and test again

    so its either
    red
    blue
    green
    black

    or

    blue
    red
    green
    black

    or

    red
    blue
    black
    green

    or

    blue
    red
    black
    green

    make sure you power off before changing wires - else drv8825 will be damaged

     
  • Ivan Nair

    Ivan Nair - 2018-07-24

    Hi Robert,

    I tried each combination of the above wiring and still am getting only one direction of rotation regardless of stepping direction. I tried the reverse direction checkbox and it still continued rotating the same way. It would reverse if I changed the wiring but it still be only that direction.

    Is there something else I may have missed ? I wouldn't put it past my less than stellar soldering skills to have a poor connection somewhere but I'm not too sure where to look.

    I really appreciate your help on this!

     
  • brownrb

    brownrb - 2018-07-25

    Hi Ivan
    Check the DIR line to the DRV8825 - Nano D3 to DRV8825 DIRECTION pin

    It should be low GND going in direction and high +5V going the other way

    You might also have a short between pin 7 and pin 8 of the DRV8825 - or pin D3 and pin D4 of the Nano.

    DIRECTION should toggle between 5V and GND depending upon the direction you are moving.

    Basically test it by setting position to 0 and motorspeed fast. Then put meter lead onto DIRECTION pjn, then tell focuser to goto say position 5000.

    Then to test oppositive state, once focuser has got to 5000, tell focuser to HOME and you should see DIRECTION change to opposite state

    Cheers
    Robert

     

    Last edit: brownrb 2018-07-25
  • Ivan Nair

    Ivan Nair - 2018-07-25

    Hi Robert,

    After testing and not getting the results I should I resoldered D3 on the Nano and it corrected the directional issues. Now everything looks like its working as it should. Thanks so much for the support and for putting together an excellent product!

     
  • brownrb

    brownrb - 2018-07-25

    Hi Ivan
    Good to hear it is now working. For bracket mounting ideas look in the folder Mounting Bracket Examples which appears when you unzip the firmware file.

    Cheers
    Robert

     

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