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I have a broken linear encoder that I want to repair...

Discussion in 'Troubleshooting and Repair' started by Dan Boy, Jun 12, 2015.

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  1. Dan Boy

    Dan Boy

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    Jun 12, 2015
    Hi, I allowed some coolant fluid get into my linear scale and now the read head won't work. I am guessing that the fluid, mainly water based has broken some of the components.

    I hope someone can them and tell me how to test and or replace them.

    [​IMG]

    [​IMG]
     
  2. Minder

    Minder

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    Apr 24, 2015
    Is it optical or inductive/capacitive?
    It could be cured by cleaning and drying, especially if optical.
    Use de-natured alcohol on the scale.
    M.
     
  3. Dan Boy

    Dan Boy

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    Jun 12, 2015
    I am guessing but I think it is optical. It reads lines printed on a piece of glass. Do you mean to clean the glass or the component?

    Thanks Dan.
     
  4. Dan Boy

    Dan Boy

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    Jun 12, 2015
    Just gave it a clean, both the glass and the sensors. A little dirt came off but it still doesn't work. Can I test the components on the PCB?
     
  5. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Hi Dan Boy
    Can you take some better pictures please they are a bit unclear. We can't see the extent of the damage
    Thanks
    Adam
     
  6. Dan Boy

    Dan Boy

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    Jun 12, 2015
    Is this any better, the thing is so damn small. I can test the components if I know what reading I should be getting.

    [​IMG]
     
  7. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Those three resistors look like they could do with a re-solder. One looks like its moved quite a bit. Or not centered during reflow, an indication of not enough solder or too low heat.
    Adam
     
  8. Minder

    Minder

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    Apr 24, 2015
    Is that the read head itself? The part the moves over the scale? It does not appear to much in the way of electronics on it, if optical there should also be opto RX TX and a part of a grating similar to the head, Unless it is capacitive?
    M.
     
  9. Martaine2005

    Martaine2005

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    May 12, 2015
    That middle resistor definitely tried AWOL during the wave soldering.
    Perhaps a good clean with isopropyl (using ear buds / qtips).
    And make sure the board is completely dry.
    Martin.
     
  10. Dan Boy

    Dan Boy

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    Jun 12, 2015
    Before I break out the soldering iron, can I test the resistors to see if they have failed?

    There are more boards to this read head but this seemed the most likely one to fail as it was in the coolant.

    Thanks Dan.
     
  11. Martaine2005

    Martaine2005

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    May 12, 2015
    Hi Dan, you can't really test a resistor without de-soldering a leg. To do so in circuit will give false results.
    First clean all boards and let them dry COMPLETELY.
    The water based fluid could still short circuit even when you think it is dry.
    Heck, I should know, my computer mainboard only got 1/4 of a can of beer.
    and wouldn't work for a week. I am typing to you now on it...
    Coolant is corrosive and gels. Clean all boards thoroughly as smd's can retain moisture underneath too.
    Martin.
     
  12. Minder

    Minder

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    Apr 24, 2015
    What make of scale/DRO is it?
    The two small bearings at right angles indicates this is the read head, it is imperative for both type that alignment is maintained.
    I don't see any optical head there, so is it possible capacitive?
    I have always found that they are fairly impervious to coolant etc, that a scale/head clean could not overcome, particularly for the optical type.
    M.
     
  13. Dan Boy

    Dan Boy

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    Jun 12, 2015
    This is the make.

    http://www.delos-tek.com/en/products/dls-w.asp

    I have now managed to confirm that there is a film of dried up coolant all over the board. I need to clean this off then. What is the best solution to use?

    Dan.
     
  14. Minder

    Minder

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    Apr 24, 2015
    You can get electronic cleaner in an aerosol can from most electronic suppliers, get the non-residue type, alternatively use de-natured alcohol.
    M.
     
  15. Dan Boy

    Dan Boy

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    Jun 12, 2015
    BTW, anyone know what type of component these are?

    [​IMG]
     
  16. Minder

    Minder

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    Apr 24, 2015
    They almost appear similar to fuseable links or contact pads?
    Do they all measure the same continuity?
    M.
    .
     
  17. Dan Boy

    Dan Boy

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    Jun 12, 2015
    I can't get any reading off them at all. On the other side there is a glass eye.
     
  18. Minder

    Minder

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    Apr 24, 2015
    They most certainly are the IR LED's (or could be Photo det side).
    M.
     
    davenn likes this.
  19. Dan Boy

    Dan Boy

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    Jun 12, 2015
    Could that be faulty? Can It be fixed?
     
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