The board doesn't control the color wheel, the color wheel controls the board. IOW, it senses the position of the wheel during rotation for timing of the image vs segment color. The wheel rotates at a constant speed. Or at least it's supposed to. In most cases, the bearings are failing and the speed isn't constant, this is detected by the projector as a fatal error and the projector is supposed to shut down, doesn't always.
Since without the color wheel, the image would be B&W, that's the most likely cause of your problem.