1995 johnson rectifier

[phoenixgold2100]

Can anyone tell me how to test my rectifier I have hooked an ohm meter to it and tested every lead reversed the probes and the only one i get a reading from is the gray tach wire. this mean it's a bad rectifier 585219 95 johnson 150
also would i add atf to my trim ? thanks guys first boat and I have a lot of questions

 

[boobie]

Re: 1995 johnson rectifier

Put ATF Dextron III in your T/T. Got a model # ??

 

[airman1094]

Re: 1995 johnson rectifier

I know on my motor the rectifier sends pulses to the tach to give it "data" so to speak. If I'm getting a tach reading, my rectifier is working! Not sure if yours is the same, mine is a 1975 after all! Should be the same principle! Hope that helps!

 

[phoenixgold2100]

Re: 1995 johnson rectifier

I know on my motor the rectifier sends pulses to the tach to give it "data" so to speak. If I'm getting a tach reading, my rectifier is working! Not sure if yours is the same, mine is a 1975 after all! Should be the same principle! Hope that helps!

Ya thats the problem my tach doesn't work. I checked the rectifier with the negative batt cable connected and after testing how it said in the manual it comes back as a working rectifier I will confirm on thursday when I start it and check voltage at the battery. I have confirmed all wiring is correct no grounds just no tach so it might be the tach it's self it's just weird because my trim gauge does not work either and both have power and grounds

does the engine have to be all the way up to check the atf in the trim? I pulled the cap and it kinda shot out a bit. engine half way up. thanks

 

[gm280]

Re: 1995 johnson rectifier

Depending on application it is sometimes hard to check (ohm out) rectifiers while they are connected up. Since there are connected to coils that generate electricity they will mask problems or mimic problems that simply may not be a problem at all. Rectifiers being simply diodes connected in a fashion to rectify (change) the voltage to DC, if one is bad it is hard to tell without isolating them first. Here is a simple diagram of a three coil output circuit to a rectifier to turn the AC into DC... If you isolate the unit you can then take a simple ohm meter to check their forward to reverse capability. Put your meter leads on each side of one of the diodes and see if it reads anything. Then reverse the meter leads and do it again. It should read some reading one way and not the other. If it reads the same both directions OR doesn’t read anything in both directions, it is bad. Do the same for all the diodes. Every diode should only read one way and not the other... If any one of the reading is bad, you have to replace the entire diode pack...that’s just how there are made.

 

[Chris1956]

Re: 1995 johnson rectifier

Phoenix, A lot of the rectifiers used in OB applications are a bridge of 4 diodes, not six as GM posted. If you have two yellow stator leads, you will have the 4 diode bridge. The correct test is to disconnect all 4 rectifier leads. Now set the analog multimeter to ohms (rX1 is good). Digital multimeters may not work for this test.

Choose two adjacent connections and test for continuity. Now switch leads on the same connections. One of the tests will show zero resistance and when the leads are switched the resistance will be infinite. Repeat test for the other adjacent connections. If you get an open circuit when testing with meter leads both ways, the rectifier is bad. Similary, if you get zero resistance both ways, the rectitier is bad.

 

[Crosbyman]

Re: 1995 johnson rectifier

If it is a plain 4 diode bridge why not just get a radio shack 25 amp 50 volts 4wb for $3.50

temporaly connect the stator wires to the 2 sine wave logo markings on the square block

the two other pins are ground (-) and +12v

connect (-) to the frame and (+) to the battery and any other red wires currently connected to the existing rectifier

restest by measuring charge voltage on the battery with engine not running (should see around 12-13v)

engine running ..should see 13-14-15 volts or so

 

[bob johnson]

Re: 1995 johnson rectifier

this is what I love about having a spare parts motor ......some tests the book as you to do, are from outer space it seems.... I like to try and narrow it down and then remove the suspect part and insert another and see if that works, if it doesn't change anything I switch it back..with electrical stuff, you really have to follow the exact path of troubleshooting....and many times it involves specialty eletronical test equipment.......best of luck bob

 

[phoenixgold2100]

Re: 1995 johnson rectifier

When I tested my rectifier I got around 1600 from both yellow wires one way and just an i on the volt meter the opposite way. I get a 10 from the gray wire both ways. anyone know what this means? lol

 

[Chris1956]

Re: 1995 johnson rectifier

Well, the rectifier should show a dead short one way and infinite resistance the other, across each of the 4 diodes. Not sure what your readings mean...

 

[phoenixgold2100]

Re: 1995 johnson rectifier

So just an I one way and zeros the other is what your saying? I'm new to ohm meters.

 

[Chris1956]

Re: 1995 johnson rectifier

OK, A 1 means dead short and zero means infinite resistance. Sounds like your rectifier is good.

 

[Chris1956]

Re: 1995 johnson rectifier

Crap, I switched it up.. I will guess that I is infinite resistance, and 0 is zero resistance. Sorry. You have a digital multimeter right?

 

[phoenixgold2100]

Re: 1995 johnson rectifier

Crap, I switched it up.. I will guess that I is infinite resistance, and 0 is zero resistance. Sorry. You have a digital multimeter right?

Ya digital reader. In my manual it says the two readings on the yellow wires should be within two digits of eachother and they are both around 1600 one way and i the other. I just have no tach. I put power to the tach on the bench and tried to get the gauge to spike putting signal to ground and nothing so I'm thinking bad tach?

 

[Crosbyman]

Re: 1995 johnson rectifier

suggested reading

Lessons In Electric Circuits -- Volume III (Semiconductors) - Chapter 3

in ohms world... 0 is 0 resistance 0 ohms Known to be called "dead short"

any other reading above 0 ohms indicates resistance to current flow which goes from being "almost or pretty well a dead a short"
to infinite resistance called an "OPEN"...as in a broked wire.

 

[phoenixgold2100]

Re: 1995 johnson rectifier

OK I don't get zeros when testing the rectifier. I have tried every setting on the meter in the ohms side. I get around 1600 on both yellow wires one way and a I the opposite way. Are you saying I should be getting zeros when the leads are reversed? 1600 one way zeros the opposite? Also I get a 10 on the gray tach wire both ways on the meter. Does any of this indicate a bad rectifier. Manual says reading one way and no reading the other and as far as I can tell i'm only getting numbers in one direction.

 

[Chris1956]

Re: 1995 johnson rectifier

You are not supposed to test the stator, just the rectifier. The rectifier must be disconnected from all wires in order to test it properly.