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  1. #11
    It drops to about 2.8 - 3.0v

  2. #12
    Hi Kev

    the voltage drop on the printer port pin to 2.8 - 3V is too small

    you should have it dropping to near 0V when the switch closes

    assuming the opto-isolators LED is powered from +5V
    this is what I'd expect for the breakout boards limit switch input

    corrected diagram
    Click image for larger version. 

Name:	tx14175 bob limit switch supply corrected diagram.jpg 
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    (arrow pointed to the wrong end of the 1K resistor on the original diagram)

    John
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by john swift; 22-03-2017 at 01:20 PM. Reason: add corrected diagram

  3. #13
    Sorry my mistake, misunderstood what you said the voltage when the switch is presses is zero volts

  4. #14
    Hi Kev

    do you use two seperate power supplies for the breakout board ?

    I have made a correction to the diagram in post 12
    this is how I expect the breakout boards input circuit to be

    Click image for larger version. 

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    from the limited detail in the photo of the breakout board the two regulator IC's appear to be LM317 plus resistors = 5V regulator for the 74HC245D IC's

    LM2576S switching regulator = 10V regulator for the analogue VFD drive

    John
    Last edited by john swift; 22-03-2017 at 02:46 PM. Reason: add ref to LM317 & LM2576

  5. #15
    Hi John. There is a 24v which I think is for fan and 5v which is for the drivers. I've been playing around with it all night but still no joy. Just a silly question but should the switches be carrying voltage ? Because mine aren't

  6. #16
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 9-10 years. Has a total post count of 2,121. Received thanks 233 times, giving thanks to others 5 times.
    There should be voltage at the switch, which makes me think you've not got the board powered correctly.

    What power supply do you have connected to the board?
    And do you have a link to any kind of manual for the board?
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  7. #17
    yes ,
    you should measure a voltage across an open limit switch wires

    about 4V if the input circuit has a 5V supply

    Click image for larger version. 

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    John

    PS
    a photo of the breakout boards supply terminals will be usefull wth
    a diagram of the breakout boards supply connections
    Last edited by john swift; 23-03-2017 at 12:31 AM. Reason: add PS

  8. #18
    Would it be best to get another bob rather than messing around with this one, which doesn't seem to be much good

  9. #19
    Quote Originally Posted by Kev2960 View Post
    Would it be best to get another bob rather than messing around with this one, which doesn't seem to be much good
    As have been said do you have the manual. Also doe this bob require two power supplies I say this because I do have a Chinese one that is powered by usb BUT the inputs won't work unless the other power supply (12-24V) is connected as the bob gives out the 0-10V for speed ref. Just a thought.
    Last edited by Clive S; 23-03-2017 at 09:44 AM.
    ..Clive
    The more you know, The better you know, How little you know

  10. #20
    I don't have a manual for the bob just for the machine itself. ive enclosed some photo's of the bob and the main board
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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