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Thread: External transformer mod for exobar pid

  1. #1
    rrm
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    External transformer mod for exobar pid

    This morning my PID collapsed.

    So rather than replace it I investigated repairing it.

    The transformer primary was open circuit.

    A common problem with Gircar pid controllers.

    I've attached "howto" in pdf to this post.


    _EXOPBAR PID EXT TRFR MOD.pdf
    Dimal, matth3wh and 338 like this.

  2. #2
    338
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    Great and very detailed writeup

  3. #3
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    A great job to get the machine up and running and for next time a direct replacement transformer is available from RS or Element14 for about $10 if you can wait a week to get it.

    When mine carked it a few years back I had a dodgy temporary transformer hanging off the pid while I waited for the new on to arrive .


    Gary
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  4. #4
    rrm
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    I wouldn't replace the original transformer with the same unit.

    They do and will fail regularly.

    An 300mA external transformer has 50% de-rating factor and is likely to last a lot longer.

    Edit:

    I'd do the mod a bit differently next time. I'd loop the Bridge rectifier Ac connections to the AC input terminals. And
    power the transformer with Ac independently of the Pid unit. The downside is you need to label the pid unit as being modified.
    Last edited by rrm; 26th September 2017 at 09:02 AM.

  5. #5
    rrm
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    A much better method...

    After a couple of days thinking about the transformer modification, and consideration of the facts:


    1) The mains wiring and LV voltage under a single sheath is not to electrical code (but still safe)

    2) The connector used on the cable is not mains approved

    3) The pid circuit board didn't sit "nicely" inside the cover because the wiring didn't allow it to.

    4) The rear cover of the pid needed to be "butchered"


    I've come up with a better, faster and neater modification procedure.

    It labelled as V2 and attached to this post.
    Attached Files Attached Files

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