John Deere 750 Tachometer

[ndmarks]

Does anyone know how the Tach circuit on a JD750 works? What causes it to indicate engine speed? I have both the parts and service manuals and can't seem to find a Tach Sending Unit.

 

[jd110]

The 750 tach is mechanical. No electricity involved. It has a cable that runs off of a miniature gearbox on the timing cover. If you disconnect the cable from the back side of the tach, start the engine and see if the inner cable spins while running. If it doesn't spin, then the cable is probably broken. If cable does spin, then the tachometer is bad.

 

[ndmarks]

That's interesting. Thank You so much. I am rebuilding a 750 and the previous user was one of those idiots that never fixed anything - if it broke, it stayed broke. They even bypassed the fuel filter. Putting the new filter assembly in is on my list of things to do. Thanks again.