Trouble shooting a Rectifier

[jayhawkokie]

My tachometer wasn't working on the 1987 bass boat I just purchased, it has a 90 Hp Merc. I'm trying to figure out if it is the instrument or someting else. i had on continuity on the gray wire so I ran a secondary wire from the rectifier to the tach, it still doesn't work, even after swapping it to the other other yellow wire terminal on the rectifier.

I haven't checked the rectifier with a multimeter yet. What kind of voltage should I read from each of the terminals on the rectifier to ground?

Thank you for any suggestions.

jayhawkokie
Grand Lake O the Cherokees, Oklahoma

 

[Barnacle_Bill]

Re: Trouble shooting a Rectifier

Testing Merc?s square rectifier

If you use an analog meter set it on the RX1000 scale.
If using a digital meter, set it on the diode symbol.

1. Disconnect the battery leads.
2. Disconnect all wires on the rectifier.
3. Connect the red test lead to ground and the black lead alternately to terminals A and C.
The meter should show continuity.
4. Connect the black lead to gound and the red lead alternately to terminals A and C.
The meter should not show continuity.
5. Connect the black lead to terminal B and the red lead alternately to terminals A and C.
The meter should show continuity.
6. Connect the red lead to terminal B and the black lead alternately to terminals A and C.
The meter should not show continuity.
7. Replace the rectifier if you do not get correct readings.

 

[Barnacle_Bill]

Re: Trouble shooting a Rectifier

Good idea to test the stator too while you have the wires disconnected.

 

[jayhawkokie]

Re: Trouble shooting a Rectifier

Thanks for the help, I'll check it out.