rectifier test

[jtcarter]

My manual says to use a ohm meter on its highest setting and test both the yellow solid lead and the yellow and gray lead. Its says to ground one lead to a good engine ground and test one at a time. You should get current going one way reverse the leads and no current the other way. It also says to test the red lead also in the same manner. Well when i ground one test lead to a good ground and test both yellow and yellow and gray actually mine are both yellow for some reason. Anyway when i test the yellow and yellow and gray leads to a good engine ground the needle on my ohm meter barely moves in one direction and doesn't in the other on both wires. I can run a test lead though from the red lead and run the other one to the yellow or yellow and gray lead and i get a reading one way and no reading the other. Does this make any sense to anyone. No reading when i test red lead by itself. Bad rectifier?

 

[Vic.S]

Re: rectifier test

Yes it makes sense. It sounds as though the two diodes on the negative side are blown but the two on the positive side are good. Dead rectifier I am afraid.

But recheck between the yellows and ground (The bolt holding the rectifier should be a good ground as the case is the negative connection if there is no black wire).

The quickest way of blowing a rectifier is to connect the battery the wrong way round. Instantly fatal!

 

[F_R]

Re: rectifier test

As a matter of explanation, there are four diodes in that thing. Each diode takes two tests, forward and reverse. It is called a bridge rectifier if you know what that means. Sounds like two of your diodes are shot. Did you have the red lead disconnected when you were getting the bad readings on the yellow-to-ground? You should have all the leads disconnected to prevent false readings from current flow through some other part, maybe far away from the rectifier.

 

[jtcarter]

Re: rectifier test

Yeah i did. All three test show low ohms. I'am relieved that i think i've finally chased down this problem. But i'am worried now. That bad rectifier took out my stator and powerpack. I just installed a new stator and powerpack and i've ran the boat on the lake until it started doing the same crap. I wish i had known that the rectifier was bad i'd never have run the motor the other day.

 

[HighTrim]

Re: rectifier test

Be sure to figure out why your rectifier blew as well. As stated, cross polarizing takes out both sides of a bridge rectifier instantly. Loose or dirty connections usually only takes out single diodes, but over time will cause a complete bridge rectifier failure. Have you mistakenly cross polarized the battery cables? If not, take a terminal cleaner to the terminals and a file to the battery clamps, make them shine.

I wonder why Johnson/Evinrude does not fuse their rectifiers as Yamaha does?

 

[jtcarter]

Re: rectifier test

Be sure to figure out why your rectifier blew as well. As stated, cross polarizing takes out both sides of a bridge rectifier instantly. Loose or dirty connections usually only takes out single diodes, but over time will cause a complete bridge rectifier failure. Have you mistakenly cross polarized the battery cables? If not, take a terminal cleaner to the terminals and a file to the battery clamps, make them shine.

I wonder why Johnson/Evinrude does not fuse their rectifiers as Yamaha does?

I might have crossed my battery charger once. I kinda think i inherited this problem since its pretty much been acting the same way the whole time i've had it. I've checked the cables and they're clean. The connections are clean at the motor too. I traded for this boat at the beginning of the year. Thought i was getting a deal. New prop, new lower unit, Pretty much all the ignition stuff new stator,pack,coils, wires. Everything except a recitifier that i now know is blown. It was stamped for 2/8/07. I assumed it might be good. But as with everything else on my lemonrude you can't assume anything. I pretty much know just about everything there is to know about this motor now. I'am the type of person if i know it can be fixed i'll be persistant until it is. Just my nature. I've also noticed there is far to many things that can go wrong with these things. They're one big headache.

 

[tipit008]

Re: rectifier test

Sorry for the silly question, but can someone tell me what a rectifier does??

Thanks.

Marc P.

 

[wilde1j]

Re: rectifier test

In this application, it converts AC from the stator to pulsed DC for battery charging, etc.