Help needed with Bus door control circuit.

Discussion in 'General Electronics Chat' started by jfrog, Jun 27, 2010.

  1. jfrog

    Thread Starter New Member

    Jun 27, 2010
    Hi, my first post and requesting help.

    I am rebuilding the passenger door mechanism on a Mercedes 609D bus.
    I have rebuilt the door rams and motor, which work fine. If directly hook up the 24v motor then it turns one way and the doors open. If I then switch the polarity, then the motor turns the other way and the doors close.

    There is a micro switch on the door rams that opens when the door is fully closed, and another which opens when the door is fully open. The micro switches are not currently connected to anything.

    There are various push buttons inside and outside the bus for opening and closing the door. The buttons are push to make contact, and break contact as soon as you let go of them. I am presuming that when an open button is pushed and released that the door should open completely without having to hold the button down the whole time. I'm assuming the same for the close buttons too.

    The original circuit board was still in place. Partly wired in.

    It is a FKI Peters Bradbury - 065-302-A4 Issue 2.

    I'be tried to understand how it works and how to wire it back in, but I'm pretty inexperienced and despite spending some time scratching my head over it, I have yet to work out what needs doing.

    This is what the circuit looks like




    Here is how it was wired in before I removed it to investigate how it works
    (There were no wires doing to right hand connection block, not shown)

    Here is what those wires did. Although I am not 100% on 10 and 11

    Here is my strange diagram of what connects to what on the circuit, which I made by poking around with a continuity tester.

    Any help would be massively appreciated!

    Thanks for your time.

    Last edited: Jun 27, 2010
  2. Norfindel

    AAC Fanatic!

    Mar 6, 2008
    What's the problem? It stopped working by itself? Someone disconnected all the wires?
    If it's something standard for the bus, you could try to get a wiring diagram, that tells you what wire goes where.

    Or you could try to find the datasheet for the relays, and try to reverse-engineer how it works, but it would be much more difficult.

    The microswitches that opens when the door is fully closed/open are likely to cut power from the relay coils that close/open the door.

    About "latching" the button presses, probably the button activates a relay that powers it's own coil from it's output.

    Does that help?

    Note: Those are only guesses based on how i would try to do it, as it would be too difficult to try to get something by seeing the board/drawings.
  3. jfrog

    Thread Starter New Member

    Jun 27, 2010
    When I bought the bus the mechanism had been mostly removed. All that was left is in the photographs. The company that made the circuit board and door system closed down.

    Thanks for your offer of help.

    I also posted on another forum asking for help.

    Someone there provided me with a solution.

    In case anyone is interested, here is a link to it