diode rectifier

[john king]

if the rectifier is bad will everthing work but the tack, I never could figure out what it did. I have two motors and the tack test different,so I think one of them is bad but both engines run fine except the tack don't work on one.1977 evinrudes 70 85

 

[Barnacle_Bill]

Re: diode rectifier

Yes it possible. The rectifier changes AC from the stator to DC to keep the battery charged. The simplest way to check it is with a volt meter. Check the voltage at the battery with the motor off then check it again with the motor running. You should see an increase in voltage if it is working properly.

 

[Joe Reeves]

Re: diode rectifier

(Small Rectifier Test)<br />(J. Reeves)<br /><br />Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction. <br /><br />Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other. <br /><br />Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. <br /><br />Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[byacey]

Re: diode rectifier

Just to add to what Joe mentioned - You can also get a reading if the rectifier is shorted, however it will read "0" Ohms. Most analog VOM meters will read about mid scale when set to the x1 resistance scale on a good rectifier.<br /><br /> A digital meter on diode test will read anywhere from 0.4 to 0.7 on a good silicon junction type rectifier one direction, and nothing the other direction. A shorted one will read "0" both directions, and an open junction will read nothing either direction.<br /><br />A shorted rectifier will tend to cause the battery to discharge while sitting and will cause the stator windings of the alternator to heat up until the rectifier burns up and goes to an open state.

 

[john king]

Re: diode rectifier

I don't have a charge system on eather motor so I take it the only thing it does is produce the pulces for the tack.

 

[byacey]

Re: diode rectifier

I doubt that they would put a stator on the motor just for a tach. Perhaps the charging wiring was removed by someone at some point in the past.

 

[Barnacle_Bill]

Re: diode rectifier

Actually the rectifier has nothing to do with the tach operating. It is just a convenient place to connect the tach to the stator output.

 

[byacey]

Re: diode rectifier

Originally posted by IBNFSHN:<br /> Actually the rectifier has nothing to do with the tach operating. It is just a convenient place to connect the tach to the stator output.

That's true, but I really doubt the manufacturer would go to the trouble of installing a stator winding merely to provide a signal for the tach. It must have been set up for charging at some point.

 

[Joe Reeves]

Re: diode rectifier

Both of those engine have charging systems. The tachometer would not function without them. Look under the flywheel for a series of insulated coil windings surrounding the inner portion of the flywheel.<br /><br />The ststor supplies AC voltage to the rectifier which converts it to DC voltage. That DC voltage is then supplied to the RED wire of the rectifier which is in turn attached to the battery cable terminal of the starter solenoid, thustly completing the charge circuit.

 

[john king]

Re: diode rectifier

Well I put a new diode in and now my tack works. that stator you are talking about sends the volts to the coils that are hooked to the plugs

 

[Joe Reeves]

Re: diode rectifier

628G.... Those stators are two fold components. Read on.<br /><br />The 3cyl model has a series of small coils that supply AC voltage to the rectifier which are designed for battery charging purposes, and they also supply the 6 pulse signal to operate the tachometer. There are also three larger coils in that stator that supply approximately 300 AC volts to the powerpack(s) internal capacitor to energize it.<br /><br />The V4 stator is designed in a similar manner (charging/tachometer), excepting that it incorporates only two larger coils to supply the AC poswer to energize the powerpack(s).<br /><br />The powerpack is the component that transfers a higher voltage to the coils, not the stator.

 

[john king]

Re: diode rectifier

thanks I am learning more every day, i knew it went to the powerpack and then the plugs