4N25 help

Discussion in 'The Projects Forum' started by Edmunds, Jul 20, 2014.

  1. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    85
    0
    Dear friends,

    I have a bad stepper driver board, that gives erratic stepper movements and I'm sure it is about the driver. While I was about to throw it out, I decided to give it a shot as the big TB6560 is an IC that I have several working drivers with.

    One thing I want to do is to short the optocouplers linking parallel port to the IC. This has helped a great deal on other Chinese items. I have read elsewhere, they don't do their job anyway. What I have on the board though, is two 4N25s and one EL817. The last one is easy, but how do you short 4N25? My initial, though, untested guess was pins 1 and 4. But that was a few seconds away from burnt 5V regulator for the board. So, obviously something is very short. Too short. Can you help with jumpering this thing correctly, please?


    Thank you for your time,

    Edmunds
     
    Last edited: Jul 20, 2014
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    If these are step/dir etc inputs how are you achieving the step/dir signal with the output shorted?
    What you are attempting is equivalent to turning the opto on, if turning off will work, jumper the input instead.
    Max.
     
  3. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    85
    0
    Short the optocoupler as in eliminate it was what I meant. These are step and dir inputs exactly.

    Jumpered pads 2 and 5 (of course, not 1 and 5 blaaa! :eek:) of the former 4N25 locations and now it works! The stepper is happy and the driver can stay.


    Thank you,

    Edmunds
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    IOW you are eliminating the isolation, which means the commons for the P.P. and the driver also need to be coupled.
    Max.
     
  5. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    85
    0

    Thanks', they are.

    Edmunds
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    Remember that connecting the drive common to P.P. common is connecting them to Earth Ground, unless using a Laptop.
    I subscribe to the Commons connected to earth ground anyway, where it is possible to be done.
    Max.
     
Loading...