Bescor MP-101 Hack

I spent a day or two hacking a Bescor MP-101 Motorized Pan / Tilt head to respond to messages from a computer via usb / arduino. Here is the first day in a series of photos. Captions and titles contain some how-to infos. I also took some notes as I was working. They are re-produced,
unedited, below:

Hotbox

Computer Controlled Motorized PanTilt Head

1. Wire Schem

Purple - slowest end of speed control (left)
Yellow - Move Left
Blue - Move Down
Black - Movement common grnd
     note: rx here - gold grey red white grey orange
                         389 x 10^2
                         3.89k ohms[?]

                         actual: 3.78k ohms

White - Move Up
Green - Move Right
Red - highest end of speed control (right)

2. power output of pan tilt is roughly 1v (1.005 it seems) to engage servo movement. Measured at DC

3. Arduino code whcih seems to work

     /*
      Fading

      This example shows how to fade an LED using the analogWrite() function.

      The circuit:
      * LED attached from digital pin 9 to ground.

      Created 1 Nov 2008
      By David A. Mellis
      Modified 17 June 2009
      By Tom Igoe

http://arduino.cc/en/Tutorial/Fading

      This example code is in the public domain.

      */

     int ledPin = 9;    // LED connected to digital pin 9

     void setup()  {
       // nothing happens in setup
     }

     void loop()  {
       // fade in from min to max in increments of 5 points:
       for(int fadeValue = 0 ; fadeValue <= 55; fadeValue +=5) {
         // sets the value (range from 0 to 255):
         analogWrite(ledPin, fadeValue);
         // wait for 30 milliseconds to see the dimming effect
         delay(30);
       }

       // fade out from max to min in increments of 5 points:
       for(int fadeValue = 55 ; fadeValue >= 0; fadeValue -=5) {
         // sets the value (range from 0 to 255):
         analogWrite(ledPin, fadeValue);
         // wait for 30 milliseconds to see the dimming effect
         delay(30);
       }
     }

4.      255 pwm output == 5v == broken pantilt head.
     seems 55 fade value is about right, providing a max output of about 1.006v

6. Aruino code which outputs correct voltage for controlling the pantilt head

     int ledPin = 9;    // LED connected to digital pin 9
     int fadeValue = 51;    // pwm output for triggering "button pushes" for the pantilt head

     void setup()  {
       // nothing happens in setup
     }

     void loop()  {

         analogWrite(ledPin, fadeValue);        

     }

Tags: , , , ,

6 comments about “Bescor MP-101 Hack”

  1. Raja Says:

    Hi Michael,
    I’m currently into time lapse and I have just purchased the Bescor 2 months ago . I was wondering if you have the circuit board diagram on the pan head for verification as I want to verify between the hand held circuit diagram with the pan head wire diagram for confirmation . I have some issues with the hand held device after sending it for repair and it will be great if you have the pan head circuit diagram instead. Thanks for your kind attention .

    regards
    Raja

  2. Pat Says:

    i’m trying to slow down my Bescor MP-101 to alms a stand still. if I replace the 3.89k resistor with a 47k with it do the trick? I don’t know much in that field.

    Thanks

  3. Wayne Says:

    With the cable that goes in to the Bescor what coloured wires are the pins? eg blue pin 1

  4. mike Says:

    Oi! Not sure at all – everything I know is in the post. And it’s been long enough now since doing this (we abandoned further dev on this part of the project since we ended up not being able to do what we wanted). Best way to figure out is if you have a volt or continuity meter, just aligator clip to one of the pins and then test the other side of the cable / circuit to see what gives you a complete circuit. Then you’ll be able to tell what goes where.

  5. mike Says:

    We actually stopped working with this guy because even with all manner of electrical modifications, we couldn’t get the motors to go slowly enough. I think it is a problem of torque / power with the servos used. So… you could give it a try but if you’re looking for super, super slow speed – you might be out of luck. :-(

  6. mike Says:

    I dont have the circuit diagram, no, sorry! And am definitely not skilled enough to reproduce it from the actual circuit. Maybe Bescor could furnish it to you… but probably not? Good luck!

speak up: