Did I damage something?

Discussion in 'General Electronics Chat' started by Dyers, Dec 11, 2013.

  1. Dyers

    Thread Starter New Member

    Dec 11, 2013
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    I bought (2) 12VAC [edited to correct: should read 12VDC] motor controllers. Each have a 3-way power switch, and potentiometer. When I bought them, I knew they had +, and - terminals for power. I previously purchased a pair of 12V adapters, and had a pair of matching 2.5mm PCB Power Jacks. My thinking was that I could run jumpers from the jacks to the PCB terminals.

    [​IMG]

    I soldered 1 lead (red) to the contact on the back, and a 2nd lead (black) to contact in the center. The schematic on the adapter shows the center pin to be +. I connected the red lead to the + terminal on the PCB, and the black to the - terminal. I did not connect anything to the contact on the right side of the jack.

    When I powered it up, the motor turned slowly. I switched from forward to reverse, and finally forward again. In a split second, the motor sped to full speed. When I tried adjusting speed with the pot., it stayed at full speed. I had not adjusted the pot. prior to this.

    I have another complete controller, but I'm feeling less confidence, and I don't want to damage a second device if, indeed, I damaged the first.

    [​IMG]

    So, what do you suggest might be going on, how to troubleshoot, and how might I best resolve it?
     
    Last edited: Dec 11, 2013
  2. inwo

    Well-Known Member

    Nov 7, 2013
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    Did you say 12vac controllers that you powered with DC?

    Or are your 12v adapters AC?
     
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  3. inwo

    Well-Known Member

    Nov 7, 2013
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    Found it on Ebay.
    It is DC input.


    Was there any warning against motor reversal while running?
     
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  4. Dyers

    Thread Starter New Member

    Dec 11, 2013
    21
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    Thanks for catching my error, and for going to the bother to track it down like that. No printed material was supplied in any language, so no warning. However, the switch is a 3 way rocker switch. For - Off - Rev. To move from forward to reverse requires stopping first, and I didn't do so hurriedly. The motor came to a complete stop before switching rotational direction.
     
  5. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    No error! I'm still guessing.

    If no warning it must be OK.

    Can you remove largest component in the middle if bad?
    Is there a part number?
    Check low ohms across the two biggest traces going to it.
    If dead short both ways it's toast.

    Are you sure about input polarity?
    Nothing else should damage it.

    You could try the other one, but I would power it with speed low and rev. switch on.
    Try varying speed, but don't touch switch until you know what is going on..
     
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  6. Dyers

    Thread Starter New Member

    Dec 11, 2013
    21
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    The potentiometer is attached with a little plastic connector, so I took the one from the other controller and put it on the first one. I've been playing with it for 10 minutes or so, now, and all seems as it should be at any speed, in either direction.

    It does not have a part number; printed on the pot, but it does say B10K. I tried to use Mouser's part selector, but there are too many variables about I which don't know enough to use it effectively.

    Whoa; now, this is weird. Just to see what would happen, I reconnected the original pot to the 1st controller I tried. It works just fine. I connected both pots to the 2nd controller, and everything works there as well.

    Thanks very much for your prompt, helpful replies. I feel like a louse for having taken your time unnecessarily.
     
  7. Dyers

    Thread Starter New Member

    Dec 11, 2013
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    When I reach to adjust the potentiometer knob, I invariably turn it the wrong direction. I'm hoping it's something that can be remedied by reversing some wiring.

    [​IMG]

    This came pre-wired. Turning the knob clockwise slows the motor. I used to things that speed up when the knob is turned CW. When I go to slow the motor, unless I am thinking specifically about it, I inadvertently turn it CCW which speeds the motor up.

    Would switching the red, and black wire connections at one end or the other solve my problem? I don't see an easy way to do that, so I was also wondering about cutting those two wires in the middle, then solder the red to black ends, and insulate with shrink tubes?
     
    Last edited: Dec 12, 2013
  8. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    If you look carefully at the white connector housing you may be able to extract the red and black cables and reinsert them. There is usually a metal tab on the terminal that prevents it from coming out.

    An alternative is to slice the heat shrink off the terminals on the pot and unsolder the red and black cables. Insert new heat shrink tubing before resoldering to the pot.
     
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  9. Dyers

    Thread Starter New Member

    Dec 11, 2013
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    Those are both great suggestions. Thanks.

    Just the one? :D
     
  10. Dyers

    Thread Starter New Member

    Dec 11, 2013
    21
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    As the simpler of the two solutions, I tried this one first, and it worked perfectly. Thank you again.

    Dave
     
  11. Dyers

    Thread Starter New Member

    Dec 11, 2013
    21
    2
    I got one of my machines put back together, and it turns out I spoke too soon. In my enthusiasm that the controller still worked, I didn't actually check rotation vs. speed. Even though I did switch the wires, and used photos of their original configuration for reverence, I still have to turn the pot's knob CCW to increase speed, and visa versa. Have I done something, or are some of them just built that way, and refuse to be modified.
     
  12. inwo

    Well-Known Member

    Nov 7, 2013
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    It has to work.
    If you exchange the outer wires on the pot it will work the other way.

    :confused:
     
  13. Dyers

    Thread Starter New Member

    Dec 11, 2013
    21
    2
    If you remember Archie's favorite name for Edith, you'll know how I feel. :( Thanks again. All's well.
     
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