In reply to your PM....
NOTE: the "T" on the board is the threshold, and the "S" on the board is the sensitivity.
I am assuming you are in FRESH water. If you are in salt water, and are operating in "salt elim" mode, the directions you turn the knob will be opposite. Even though the discriminate mode is silent, you must ground balance the machine in all metal fast before hunting in discriminate. Set it in all metal fast, get in the water about 3 feet deep, raise the coil above the ground about a foot. Now, lower the coil to the ground and see if the sound increases, decreases, or stays the same. If it increases, turn the ground balance knob CCW (CW for salt). If it decreased turn the knob CW (CCW for salt). You are looking for the threshold to stay the same. If your machine still chatters in the water you are either picking up small bits of iron, or the sensitivity is set too high. To much sensitivity is usually the problem. The sensitivity is inside the machine on one of the control boards inside. There are 3 adjustments on the boards inside, threshold, sensitivity, and volume. The volume is on a different board than the threshold and the sensitivity, and has a different white knob. Mark the position of BOTH of the potentiometers (blue square things) that are on the board attached to the front faceplate with a sharpie, then with the coil away from metal (this can be done on the kitchen table) turn the one closest to the center of the back of the faceplate CCW to turn down the sensitivity. You will have to do this a little at a time till your machine is stable in your hunting environment. The other blue pot on the board is the threshold, set that one where you barely hear the tone. If you have any more questions just let me know. I will post this on the board with a picture. HH Joe
