Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums - Reply to Topic
Where does this wire go?
Includes Electrical mods, Lights, Stator,
Rectifier, Diagrams, etc

Thread: Stator r/r Nightmare Reply to Thread
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  Topic Review (Newest First)
06-04-2019 06:47 PM
Spockster Been happy with the Shindengen F20A MOSFET, wiring was easy.
06-04-2019 01:31 PM
michiganteddybear MY basic thoughts are if it passes the on bench testing, then the next test that needs to be done is on the bike in operation.

if it fails bench testing, its not gonna pass operational testing (or if it does for some reason 'work', it wont for long)
06-04-2019 01:18 PM
Originally Posted by Spockster View Post
Ohm testing for the R/R is in the repair manual.
This is true but isn’t that for a disconnected RR? And what is the best recommended RR for this bike? I’ve read a lot of conflicting opinions
06-03-2019 07:36 PM
Spockster Ohm testing for the R/R is in the repair manual.
06-03-2019 06:25 PM
Thorn Yes and no ... Using a continuity tester you can check to see if the rectifier is working correctly, but without an electronics testing bench it'd be hard to test the regulator aspect.

You should be able to get current from all stator connections to positive dc pin, but no current from positive dc pin to stator connections. Similarly, you should be able to pass current from the dc negative to all stator connections, but not the reverse.
06-03-2019 05:27 PM
mmart Ah ok, great explanation. Feel like I’m back in tech school. (Scary I remember that stuff). I’m guessing other than seeing the result which is the wires cooked, there’s no real way to test that because mostly everything you mentioned is internal to the RR
06-03-2019 04:49 PM
Originally Posted by mmart View Post
Shunts across phases?? Explain what you mean there.
@mmart :
The shunting/dumping happens on the 3 phase side. The R/R detects the ouput voltage on the DC legs, and if the desired output is exceeded, then it causes semiconductors (wired in parallel to the rectifying diodes) between the legs of the 3 phase input to act as resistors, allowing some of the current to flow directly from higher voltage phases to the lower voltage phases (they are neither ground, nor neutral. they are just different phases). This drops the voltage of the waveform being rectified.

Regarding the OP's overheating wires:

The semiconductor (either thyristor or mosfet) doing the shunting generates heat when it acts as a resistor, so R/Rs get hot when the stator is generating more energy than the bike is using. They overheat and blow out when they cannot release enough of that heat to the environment. (Too much current through the resistors, or not enough cooling). Mosfets generate less heat when shunting since they are more 'fast switches' than resistors, so they don't suffer heat-death as easily.

If the R/R is incorrectly sensing too high a voltage, it will effectively drop it's internal resistance to 0, shorting the windings of the stator together, melting the yellow wires, and likely overheats the insulation on the stator windings, leading to a failed/shorted stator.

A R/R can also fail such that a diode can incorrectly pass current in reverse, which is a short between the positive and negative of the battery, melting the DC harness.
06-03-2019 07:51 AM
mmart Shunts across phases?? Explain what you mean there. Because the the 3 phases of the stator hit diodes in the rectifier, diodes pass current in one direction only and block the one side of each alternating current coming in, which in electronics is “rectification” then based on load the regulator portion “dumps” unused current to the ground or common. You can call it shunting if you’d like. Anything but “shorting” to ground works.
06-03-2019 02:51 AM
Thorn That's what I thought, TonyO, but wasn't sure since everyone keeps saying the regulator "dumps to ground" instead of "shunts across phases" or whatever the appropriate term would be. Thanks for the clarification that the two systems are not sharing some sort of floating neutral/ground.
06-02-2019 06:33 PM
mmart Tried to respond to your PM Rwhipple but could not
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