1976 75 hp johnson rectifier problem

[sandre1957]

I installed a new rectifier on my Johnson this morning and ran it for 20 minutes and the voltage was about 13.6 volts at 5000 rpm. Once I stopped and then restarted the voltage went to a max 12.6 volts. I had this happen on another and thought I had a bad rectifier. I think a diode has gone out. What could be causing this?

 

[ezeke]

Re: 1976 75 hp johnson rectifier problem

You can kill a rectifier almost instantly by reversing the battery cables, testing the rectifier with anything with voltage, disconnecting the battery while the motor is running, loose cables or bad cables that have the effect of disconnecting the battery while running, or overloading the rectifier. <br /><br />A weak or improper battery such as a sealed automobile battery can also do the deed.

 

[sandre1957]

Re: 1976 75 hp johnson rectifier problem

I did not test the new rectifier. I did not disconnect the battery while running the motor. The battery turns the motor over easily could the cables still be bad? Could there be a bad connection around the rectifier area. Possibly a bad ground. All I did was turn the motor off and then back on.