Re: Older Minkota 565
Here's the deal. The speed switch controls the motor speed the same way the heater fan on older cars was controlled -- by wire wound resistors called speed coils that drop the voltage to the motor. There are probably two of them if you have a three speed motor and they are probably located down in the motor housing as they do get hot. To test the switch, remove it. Connect one lead of an ohm meter to the black lead and the other lead to one of the other wires. Move the switch through the various positions and see if any of the settings indicates continuity. Then repeat for the next wire and the next, etc. What you need to determine is which wire going into the switch is carrying +12V. Depending on the switch setting, one of the other wires feeds 12v to the speed coils in the motor. In high speed, the speed coils are bypassed so its my guess the medium speed coil is burned out. The speed coils are connected in series so resistance is additive. Connected to the top of the two resistors presents the most resistance and therefore the slowest speed. The medium speed connection is between the two resistors so only the lower one is in the circuit. However, if that coil is burned out, you lose both low and medium speeds. I You can check the speed coils without disassembling the motor using the same logic. Determine which wire from the motor is ground. Connect one ohm meter lead to it. Then touch each of the remaining leads. The one that shows coninuity is high speed. The other two should show open if the medium speed coil is bad. If the low speed coil is open the medium coil would still function. If both are burned out, you again would have continuity on only the high speed line. If I had the time I'd draw a you picture but I think you should be able to figure this out. If the switch is bad you will need to get one from Minnkota. Otherwise you can modify things and get one from an electronics surplus store or electronic supply store in a larger community.
