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Linear actuator limit switch replacement/repair

  1. May 2, 2016 #1
    Linear actuator spec.: 400mm stroke, 6000N, 2 limit switches, 5mm/sec, 12V DC supply, BIBUS IP65 casing.

    One of the limit switches of my LA (Linear Actuator) seems to have burned out. This happened because I accidentally plugged the LA leads into the AC mains socket (my LA is rated to run at 12V/24V DC). I could guess which limit switch burned-off from the way the relay erratically turned on-off everytime I reached one end of the LA. I would like to know the best way to replace the limit switch at the top-end. I've attached a pic showing the IP65 motor cover off. I want to seek advice before I take any of the motor screws off. How do I reach the limit switch at the top-end of the LA?

    And some tips on where I could buy a replacement limit switch would help a lot.

    Pics are in attachments.
    LA repair1.jpg LA repair2.jpg
  2. jcsd
  3. May 8, 2016 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. May 8, 2016 #3


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    I am surprised that more was not damaged by the HV AC. Does the motor still work?
    There is also usually a diode wired across the limit switches to make it possible to reverse back from the limit.
    You will need to dismantle the unit to access the switches. Depending on construction, that may be a somewhat destructive process.
    Once you have exposed the faulty switch you may find that it is repairable, it may be harder to find a replacement or make another fit.
    Search the well known marketing websites for a replacement unit. It will probably be available at a low cost.
    Take care. Avoid HV DC.
  5. Jun 26, 2016 #4
    Apologies for the late reply. The motor no longer works. Hopefully its because some passive component got burnt-up. 1 good thing that seems to have emerged is that I have come closer to understanding the inner workings of the linear actuator. Please find attached the pics with descriptions of the parts inside the actuator.
    FYI- I've ordered the limit switches from China. They are very cheap and require soldering to assemble. This actuator is high precision but one has to take care of the power supply.

    Attached Files:

  6. Jun 27, 2016 #5
    You might as well replace the Diode S2M at the same time. It is rated 1000 Volt, 2 Amp. Do the same for the other limit switch.
  7. Jun 27, 2016 #6
    S2M implies surface mount? Then I'm thinking of using the 1N5408 as per the spec sheets. Yeah I see the smd diodes on top, numbers blackened out . Thanks for the tip.
  8. Jun 27, 2016 #7
  9. Jun 27, 2016 #8


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    It is highly probable that the motor was destroyed, the limit switch burned out due to the current surge when the motor failed.
    You need to see if you can get the motor working on 12VDC before you start buying and fitting replacement parts. The power diodes are the least likely components to fail.
  10. Jun 27, 2016 #9
    Aww, all the magic smoke leaked out.:H
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