Driving HP LaserJet Stepper Motors

Discussion in 'The Projects Forum' started by Navigator135, Oct 13, 2011.

  1. Navigator135

    Thread Starter New Member

    Oct 13, 2011
    2
    0
    I am in the earliest stages of building a 4 axis CNC router. I have acquired a raft of HP LaserJet stepper motors and intend to either use these or, finding them insufficient, at least using them to prototype the router and changing them out for more powerful motors later.
    The problem is that, after reading vast amounts of information regarding stepper motors, on the internet, I’m finding little-to-no correlation between what I’ve read and these motors. For example, in seems as if stepper motors have 4, 5, 6, or 8 wires. The ones I have have 7, 8, or 9 wires. The ones I read about have color coded wires, mine have a single color for all wires. The ones I see on the I/N have the wires connected directly to the motor, mine have the motor soldered to PCBs and the wires coming off of them to another (driver?) PCB.
    I‘ve tried various tests with a VOM and by shorting the wires to one another but do not get the results described in my readings on the I/N. I assume the circuitry on the PCBs may be hampering the results.
    I’ve searched the I/N using the brand and model information off the motors to see if I could find some schematics. All I found was offers to sell me more motors.
    The motors do have markings on the PCBs that might help the informed out there, but they do not correlate to the terms used on the I/N regarding stepper motors. For example, the I/N discussions reference the A+, A-, B+, and B- windings, the PCB for the motor labeled RH7-1331, DNQ15A01L18A has the following markings: GND, GND, MON, 24V, 24V, MRDY, and HALF; the PCB for the motor labeled Nidec RK2-0275-02, 50M0603020, has following markings, Vcc, Vcc, /FGS, /DEC, /ACC, GND, GND, NC; and PCB for the motor labeled Nidec RK2-0273-02, 50M0603010, has following markings, Vdd, Vdd, Vdd, FG, /DEC, /ACC, GND, GND, GND, NC. Now, just to show I’m not a blithering idiot, I DO realize that 24V means 24 volts and that GND means ground and NC means no connection and I assume that /DEC and /ACC mean decelerate and accelerate, respectively. Also, I’ve been told the Vcc and Vdd have to do with voltage input so, again, I assume these would correspond to the rated voltages (24V in all cases) of the motors. However, none of this correlates to what I’ve read about stepper motors, or, at least, I do not see the correlation.
    If someone could show me how I can connect these to a commercial, low-cost stepper motor driver or to an Arduino or Arduino driving a stepper driver that will allow me to control them through a PC using CNC software, I’d greatly appreciate it.
    I can provide pictures of the motors on other associated PCBs on request.
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    It sounds like the steppers you have, have the controller built in.... so trying to hook them up like a standard stepper will not work, you will either have to take the steppers off of the circuit boards and connect directly to the motor leads or figure out how to get those to work.

    But then again, I have taken a lot of motors out of HP laser jet printers, and all the ones I have are Permanent magnet DC motors with speed controllers built in..... the flat one that spins the mirror is a BLDC motor, the rest of the motors have a black disc attached to the back of the shaft, which is the encoder they use to tell how many "steps" the motor has taken....... if you look at the motors directly bypassing the circuit board, how many leads does the actual motor have??
     
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
    1,531
    BMorse is right. The last couple of printers I tore apart had BLDC motors in them. Maybe used as a DC servo motor?
     
  4. Navigator135

    Thread Starter New Member

    Oct 13, 2011
    2
    0
    The HP LaserJet 4000, 4050 Service Manual refers to these motors as the "Main" motor. The Nidec motors are attached to PCBs by four solder points. The PCBs are 3.75 in X 2.5 in and the motor diameter is 2 3/8 in. See attachment. The other one (no name brand shown, Model RH7-1331) appears to have three solder points on the PCB.

    Do I do this by trial-and-error, or does anyone have an idea whether or not these motors are "positionable" such as steppers?

    In looking up BLDCs vs. Steppers, it seems as if they are pretty much the same in that they are "segmented". Can they both be precisely positioned and if so how?

    Given the specific pin notations in the original post, can anyone tell me what signals I need to send to the pins to get the results about which I'm asking?
     
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