An external endoscope light source system includes light emitting diodes for providing a light output to an endoscope. The light is provided to a fiber optic cable for transmission to the endoscope. A fiber optic receives a portion of the light output and provides the output to a color sensor for sensing color values. The color values are provided to a controller that adjusts power to the various LEDs to provide a white light output. Instead of a color sensor in the light source, the light source can receive a white balance signal from a video camera provided for an endoscope. The white balance signal varies intensity of light output from each of the LEDs to obtain a white light output. The camera also provides shutter speed of a camera image sensor to the light source. The shutter speed is used to pulse or modulate the light output only when the shutter of the camera is open. By modulating the light output by the light source, the amount of heat generated by the light source is minimized.