Automated Fixtures American DJ Spot 250 repair

[Tallenpro]

I am in need of some advise on repairing an American DJ - DJ Spot 250 moving head. The color and gobo wheels are not responding properly to commands. Both motors are trying to move, and occasionally move to the correct position. Mostly the motors do not go to the correct positions or just slightly vibrate and stay where they are. I have replaced the motor driver chip whithout any change. I contacted tech support at ADJ and the best I got from them was to send it back to them for repair. As this is not an expensive instrument, I would like to keep the repair cost to a minimum. I feel that I am geting DMX signal to the onboard converter, but perhaps the motors are defective, or the main circuit board possibly could have some bad IC's. Any suggestions would be greatly appreciated. Thanks

 

[JD]

Quivering without proper movement is usually a symptom of the two-phase stepper motor not getting both drive phases. Often it is a drive chip (which you already replaced) but it can also be a wiring problem or an open coil in the motor. The fact that two of them went out kind-of causes me to lean away from the motor as both would have had to fail. I would scope the drive signals to the motor and then compare them to the drive signals on a known good unit. Could be you are missing a dc buss to the chip that drives them, or it could be a processor problem, where the drive chip is being sent a garbage signal.

 

[lightman02]

Quivering without proper movement is usually a symptom of the two-phase stepper motor not getting both drive phases. Often it is a drive chip (which you already replaced) but it can also be a wiring problem or an open coil in the motor. The fact that two of them went out kind-of causes me to lean away from the motor as both would have had to fail. I would scope the drive signals to the motor and then compare them to the drive signals on a known good unit. Could be you are missing a dc buss to the chip that drives them, or it could be a processor problem, where the drive chip is being sent a garbage signal.

Good point, I have seen issues with the main wiring harness on these fixtures. I would bet you have one or more broken or breaking wire causing the issue. I would get a meter and do a test of each of the wire leads going to the board.