Linear actuator limit switch replacement/repair

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Discussion Overview

The discussion revolves around the replacement and repair of limit switches in a linear actuator that was damaged due to incorrect voltage supply. Participants explore the implications of the damage, potential repairs, and sourcing replacement parts.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes the specifications of their linear actuator and the issue of a burned-out limit switch due to connecting it to AC mains instead of the rated DC supply.
  • Another participant expresses surprise that more components were not damaged and notes the importance of a diode across the limit switches for reversing functionality.
  • There are suggestions that dismantling the actuator may be necessary to access the faulty switch, with a possibility that the switch could be repairable.
  • A participant mentions having ordered replacement limit switches from China, highlighting their low cost and the need for soldering.
  • One participant recommends replacing the diode (S2M) along with the limit switch, suggesting that it is prudent to replace both limit switches.
  • There is a discussion about the specifications of the diode, with one participant considering using a different diode (1N5408) based on size and specifications.
  • Another participant raises the possibility that the motor itself may have been destroyed due to a current surge when the limit switch failed.

Areas of Agreement / Disagreement

Participants express varying opinions on the extent of the damage and the likelihood of the motor being functional. There is no consensus on the condition of the motor or the best approach to repair.

Contextual Notes

Participants mention the need for careful handling of components and the potential for destructive disassembly, indicating that the process may not be straightforward. There are also references to specific components and their specifications, but no definitive conclusions are reached regarding the repairs.

Who May Find This Useful

This discussion may be useful for individuals interested in repairing or replacing components in linear actuators, particularly those who have encountered similar electrical issues or are looking for advice on sourcing parts.

marellasunny
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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.
Thanks!
LA repair1.jpg
LA repair2.jpg
 
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.
 
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.
 

Attachments

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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.
 
Tom.G said:
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.
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.
https://en.wikipedia.org/wiki/1N400x_general-purpose_diodes
 
marellasunny said:
The motor no longer works. Hopefully its because some passive component got burnt-up.
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.
 
marellasunny said:
...numbers blackened out .

Aww, all the magic smoke leaked out.:H
 

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