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Motor controller question

Discussion in 'Electronic Basics' started by [email protected], Oct 26, 2005.

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  1. Guest

    Hi. I've taken apart an old laserjet printer and I want to use the
    high-speed motor that the reflects the laser.

    Here's an image of it:

    I measured the voltages on the 4 pins at the bottom. Funny thing is,
    they all seem about the same even when the motor is not spinning, so I
    must be missing something.

    Here they are, anyway: +?, -22.5v, -19.0v, -22.5v
    It's been a while since I've done any electronics, so I hope that makes

    Can anyone tell me what I'll need to get something like this running?
    Will it involve more circuitry, or simply wiring some cells up the
    right way?

    Thanks, Justin.
  2. I don't have experience with this exact motor, so I will make some

    This sort of application requires very accurate speed. I suspect that
    he motor is a moving magnet, synchronous 2 phase AC motor. The chip
    at the bottom is probably a dual H bridge motor driver and speed
    control custom chip that supplies 2 phase AC to the windings in the motor.

    You mention measuring the motor voltages. What did you use to make
    these measurements? You will probably need an oscilloscope to see
    what is driving this motor.
  3. Guest

    Just a basic multimeter. Don't have an oscilloscope.

    One funny thing that I can't understand is that only the + seems to be
    connected to the board. The 3 other points don't seem to lead anywhere,
    I've check both sides. And there's nothing else earthing to the chassis
    or any other part either.

    Guess I'll be lugging along the rest of the laserjet's internals if I
    want to use it.
  4. Are you saying that the multi pin connector has only one wire
    connected to it, or that the other wires don't connect to anything at
    their other ends? At the very least, the board needs two power
    connections (positive and negative). But I would have expected there
    would be several control lines as well.
  5. Guest

    My mistake, they are there, it's a dual layer board, which I hadn't
    seen before. Had to shine a 5mW laser to see them.

    The tracks go straight to a connector, then to the power supply board,
    and to a chip. So it looks like I'll have to find another motor unless
    I want to lug around 2 boards and a 240v supply ;)

    Thanks anyway.
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