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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Mini Lathe > SIEG C2 control board help needed
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  1. #1
    Join Date
    Sep 2016

    SIEG C2 control board help needed

    Hi gents, I recently purchased a C2 in non working order for a song knowing it needed a new controller board. Before I order one I need to know where a couple of loose wires belong if someone would be so kind as to assist. The previous owner had pulled stuff apart and has given up leaving them loose.

    The reason for the problem is easy to spot, look at the state of this PCB track
    Something fried it and bad, it looks to lead to one of the MOSFETS. Someone has had a scratch at it and whatever the fried it was left scorch marks on the control board cover. The track itself is totally melted away as you would expect if a power MOSFET shorted.

    As I said before I replace it I need to know where the wires he left loose are supposed to end up.

    These two blue ones (which I assume are from the chuck guard cutout switch) go nowhere at the moment. Please excuse the state of the machine, he gave it a good coat of lanolin before storing it away so its covered in a layer of oily dust which I see no sense in disturbing until its ready for use.

    As you see the board is in a terrible state not sure if this was from before or after it blew. The brown and blue power wires are also loose, which terminals on the stop switch do they go on? Well, I assume that's where they go.

    Last but not least the brown (or faded orange) and black wire shown here marked K4 also goes nowhere but its the board end that is attached this time. I'm assume the terminal next to it should be empty?

    If I can get this sorted I will have an operating lathe and be a happy man so thanks in advance for any help and assistance that can be offered.

    Regards, Col

  2. #2
    Join Date
    Dec 2010

    Re: SIEG C2 control board help needed

    This should get you in the ballpark - it is a 120 volt version but the wiring is pretty much the same.


    Your SCR's are probably cooked, and probably more since that foil won't blow unless he installed an oversize fuse. Give it a bath with soapy water and let it dry out in the sun for a day or so before re-powering.


  3. #3
    Join Date
    Sep 2016

    Re: SIEG C2 control board help needed

    Thank you sir, as soon as I get half a chance (what is this thing people call "spare time"?) I'll see if that does the job!

  4. #4
    Join Date
    Mar 2007

    Re: SIEG C2 control board help needed

    looking at the photos in this case you don't have FET's to control the current
    (this thread has details of the FC250J/230V boards - speed control pcb for Clarke CL300 lathe | Model Engineer)

    looks like you have an XMT-2325 board
    if you look a the 5 components on the heatsinks and search for the data sheets
    you will find you have 3 diodes and 2 thyristors

    2 diodes and the 2 thyristors form a controlled bridge rectifier
    the 3rd diode helps to protect them from the back emf from the motor



    your lathes speed control is more like this -

    Variable speed controls - The Warco

    Click image for larger version. 

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    C2 lathe from Machinemart
    Attachment 335346

  5. #5
    Join Date
    Sep 2016

    Re: SIEG C2 control board help needed

    Ok, that looks closer to the point. I am gathering the SIEG range is not widely sold in the US? These things are everywhere in the EU and here in Australasia.

  6. #6
    Join Date
    Jul 2021

    Re: SIEG C2 control board help needed

    Hi Pete I also have one of these Sieg lathes that the Capacitor (location VR1) has exploded to the point there is no trace of numbers for replacement. Would you possibly know what size capacitor this would be? Or possibly have access to a Schematic for this board. XMT-2325

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