81 Johnson 90hp Rectifier Change - Going from 4 Wire to 3 Wire Rectifier

[smoedog]

My current rectifier isnt charging and not driving my tach. I ordered a new sierra rectifier which is a 3 wire. The one my motor is a 4 wire. I'll try to lay it out below.

Rectifier Wires --------> Terminal Board/Motor Wires

Red Red

Yellow Grey (Tach Wire)

Yellow/ Blue Yellow Coming From Stator/Feeding Regulator

Yellow/Grey Yellow/Grey Coming From Stator


So Just to make with my new rectifier




Red to Red

Yellow to Yellow

Yellow to Yellow Gray as well as grey Tech wire

Just wanted to make sure before I hook this up.

 

[gm280]

Are you saying that your stator has three wires coming from it? If so, how are you going to wire those three wires up to the new rectifier? I don't see your idea of wiring up your new rectifier working the best... What you are doing is going from a three wire output stator system to a typical bridge rectifier, or a two wire circuit. So one segment of the stator will not be used for charging your battery...JMHO!

 

[smoedog]

No, My stator has 2 wires coming from it. A yellow and a yellow/grey Both feeding my rectifier.

Then I have a red coming from my rectifier feeding the red going into the motor harness. Then I have a seperate yellow coming out of my rectifier and the only thing it is feeding is the tach wire.

So going by this diagram, It looks like the rectifier I have now is not original to this motor. The part number on it is 511938. And it looks to be a rectifier of smaller johnsons with 3 wire stator.

 

[F_R]

Motors with two wires from the stator use a 3-wire rectifier. That is a bridge rectifier.
Motors with three wires from the stator use a 4-wire rectifier. That is a 3-phase system

In each case, the extra wire is the red one going to the battery.

Actually, the tach doesn't care which yellow wire it is connected to as long as it is also connected to the rectifier. Exception: Some motors with a voltage regulator.

 

[smoedog]

Ok, So I just hooked it up and the tach works, but now I am still not charging. Battery voltage is 12.6, at idle I am getting 12.7 and at 3000 rpm im getting 12.9v.
So are their instructions on testing the stator itself?

I tried checking a/c voltage across the stator wires with it running but my HF Meter was picking up to much interference from the motor. Not hooked to anything it was going crazy lol.

But I ohmed out the stator wires. Both wires to ground were open, and checking resistance across the 2 stator wires, I was getting 0 resistance.

 

[Vic.S]

Ok, So I just hooked it up and the tach works, but now I am still not charging. Battery voltage is 12.6, at idle I am getting 12.7 and at 3000 rpm im getting 12.9v.
So are their instructions on testing the stator itself?

I tried checking a/c voltage across the stator wires with it running but my HF Meter was picking up to much interference from the motor. Not hooked to anything it was going crazy lol.

But I ohmed out the stator wires. Both wires to ground were open, and checking resistance across the 2 stator wires, I was getting 0 resistance.

You measured the volts at the battery apparently but did you check the volts on the red rectifier output wire ?

I have measured the resistance of my stator coil But I forget the readings..... A few ohms IIRC but definitely not zero.
You did have the stator wires disconnected from the rectifier I hope ?

It sounds as though your stator might be completely shorted out.
You could try testing the stator with a small wattage 12 volt bulb connected directly to the yellows.

 

[Crosbyman]

http://www.ebay.com/itm/2-Pcs-Bridg...905?pt=LH_DefaultDomain_0&hash=item258f71a9e9

try this

 

[Vic.S]

http://www.ebay.com/itm/2-Pcs-Bridg...905?pt=LH_DefaultDomain_0&hash=item258f71a9e9

try this

Thats a 3 phase rectifier. In fact 2 of them! The Op does not need a three phase one
The one he has obtained from Sierra should be the correct one

 

[Crosbyman]

misread.. sorry seems he was talking of a 3 phase type

ho well anybody needing 3 phase rectifiers take note!! cheap

...but looking a the internal design of the 3 phase unit it would probably work quite well with only 2 phases (stator AC volts) going in and +12v and ground on the 2 pin side .

Capacity and heat sinking would also prove adequate amperage and volts Wise

 

[Vic.S]

sorry duplicated post

 

[smoedog]

Thanks for the input Vic. Yes the stator was disconnected from the rectifier when I tested it. I just found a page that lists the specs and it says 450-600 ohms. I guess it's off to look for a stator for this thing now

 

[Vic.S]

Thanks for the input Vic. Yes the stator was disconnected from the rectifier when I tested it. I just found a page that lists the specs and it says 450-600 ohms. I guess it's off to look for a stator for this thing now

450 to 600 ohms cannot be right for the resistance of the stator coil. You'd only get a few mA output if it was that high. Earlier I said it should be a few ohms but i have rechecked mine. Actually a three wire 5A stator but the resistance of each half is only about 0.5 ohms. Perhaps the specs you are reading say 450 to 600 milli-ohms . That would be right.

There is an online troubleshooting guide on the CDI Electronics website that might be worth a look

The fact that your tacho works sort of suggest the coil might actually be OK.

I'd do some more investigation before rushing out and buying a new coil. You dont want to spend $200 unecessarily or go to all the trouble to fit it.

Check that you have continuity from the rectifier to the battery. (Positive and negative/ ground) Is there a fuse that might have blown?

check the stator output with a bulb as I suggested.

I note the parts list also shows a separate regulator ( unusual because they are more commonly combined with the rectifier) but it may only be fitted to models with a 10 amp stator, not a 6 amp one. Thats commonly models with power tilt and trim IIRC. If there is a regulator you might want to by pass it to check things out. It could be your trouble even!

 

[smoedog]

Hey Vic, I wanted to say thanks for helping me out. To get on the same page this is the wiring diagram I am using and so far it seems spot on to the motor. http://www.maxrules.com/graphics/omc/wiring/80_81_V4.jpg

Now. I hooked up a 12v automotive headlight bulb which Was fully lit at idle. If needed I will rig up a 120v bulb. I checked the voltage coming off the regulator and it was a steady 12.8-.9v.

Now checking voltage coming from the rectifier, I can't get a smooth reading. It is all over the place. I saw voltages from 6v up to 13v. I tried with 2 seperate meters and got the same results.

Continuity is good from the rectifier to the battery side of the solenoid.

You brought up the regulator. The regulator is no where in the charging system. At this point I'm lost.

 

[gm280]

smoedog, were you trying to read the voltage on the proper setting on the meter. If you try to read the voltage coming from the stator, it is AC. If you try to read the voltage out of the rectifier, it is DC...

 

[smoedog]

Ya, I made sure to check my meter. Thanks tho

 

[F_R]

Back to basics: Have you removed and cleaned the battery cable connectors at the battery? Don't just look at them, CLEAN them shiny bright and reassemble correctly. Your voltage jumping all over the place suggests loose or dirty connections.