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  1. #1
    Join Date
    Jul 2013
    Posts
    2

    Db25 1205 bob

    Hi, yesterday I'm trying the electronics. All work successful. All axis work fine. But today not. If I start the computer the let witch indicate the power on is turn on. That's mean the board drain power from lpt and not from external power supply 5volts witch is still off. The led is light little bit lower as with the eternal power on. And the big problem is that, the motors don't move.. I don't know where is the problem.. Broken lpt port, or breakout board.. Please help. Brandon

  2. #2
    Join Date
    Mar 2007
    Posts
    2083

    Re: Db25 1205 bob

    Hi Brandon

    do you have a link to the manual for the 1205 BOB ?
    do you have a multi meter ?

    I only found a photo of the BOB

    Attachment 301960

    I assuming the two 16 pin IC's will be 74HC14 inverters

    with no power to the board and a logic 1 (+5V) on any of the printer port outputs
    the BOB will work to some degree

    current will flow via the IC's input protection diodes to the positive supply pin 16
    and power the other IC and the LED indicator at a reduced voltage

    note - if all printer port pins are at a logic 0 (0V) the board will stop working

    Attachment 301966

    check you have power to both power supply inputs for the pc interface and output side of the BOB

    a photo or diagram showing how you have connected the board will help



    John

    PS


    high resolution photos of both sides of the breakout board will make it possible to trace the circuit
    and then work out how to test it` in more detail

  3. #3

    Re: Db25 1205 bob

    Hi
    I have a problem where I do not see any pulses coming through on pin2, which is my step pulse, but I do see the direction pulse changing. If I check the parallel port of the computer I do get the correct signals. Please advise.

  4. #4
    Join Date
    Mar 2007
    Posts
    2083

    Re: Db25 1205 bob

    since my reply in post 2

    I have traced this circuit for the BOB

    Attachment 401404

    with the PDF data for the 74HC14 IC

    Attachment 401406

    you should be able to follow the step signal from the printerport pin
    to the input pin of one of the 74HC14 IC pins

    and then from the corresponding output pin to the opto isolator


    John

  5. #5

    Re: Db25 1205 bob

    Hi John
    I have downloaded port monitor app and can control the pins through that. If I switch pins on and off, I do get that coming through. It is only when I run mach3 that I do not get my step pulse. I do get my direction pulse. Any advise on that.

  6. #6
    Join Date
    Feb 2008
    Posts
    644

    Re: Db25 1205 bob

    Quote Originally Posted by Johan1007 View Post
    Hi John
    I have downloaded port monitor app and can control the pins through that. If I switch pins on and off, I do get that coming through. It is only when I run mach3 that I do not get my step pulse. I do get my direction pulse. Any advise on that.
    Its possible your step pulses are too short to be passed through the very slow OPTO couplers on the board.
    you could try doubling your step time until it works to get an idea of how slow...

  7. #7

    Re: Db25 1205 bob

    Quote Originally Posted by PCW_MESA View Post
    Its possible your step pulses are too short to be passed through the very slow OPTO couplers on the board.
    you could try doubling your step time until it works to get an idea of how slow...
    On further investigation, we found that the opto couplers is switching to slow, the data sheet specifying a rising time of 18µsec. The max we could managed to set it in Mach3 is 15µsec. At the end of the day it is just a bad quality board.

    Have decided to go for something better.

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