rectifier voltage

[jasona]

Hi,
I have a 1989 Merc 80hp 3cyl. I took a volt meter to the two yelow wires coming off my rectifier, and they each measured about 5.5 to 6 volts. Is this ok? You see, my tach was acting really funny, so I took my volt meter to the rectifier and received no reading off either yellow wire. I loosened and retightend the connections on the rectifier, fired it up and I got mesurements of 5.5 to 6 volts on both, and my tach started working. Are the readings I'm getting from my rectifer too low? Thanks!

 

[j_martin]

Re: rectifier voltage

The yellow wires are the AC wires from the stator, and the rectifier is a full wave bridge rectifier. The clamping action of the rectifier and voltage regulator or battery combined severely distory the AC waveform. Either a DC or AC measurement from either yellow to ground is unusable information. The tachometer makes use of this distorted waveform as input to a pulse counter/integrator (electronic tachometer)

The red wire is connected to battery, usually at the solenoid end of the battery cable. It should read near 12 volts with the motor off, and higher if it's running. If the rectifier is working, the tachometer input is good.

Pay attention to the ground screws in the base of the rectifier also.

hope it helps
John

 

[jasona]

Re: rectifier voltage

Thank you John. That is a big help.
Jason