Rectifier or Stator sends signal to Tachometer

[Parachute Adams]

Recently purchased a new Faria 7000 RPM Tachometer to replace the old busted/broken original tachometer.

I performed a preinstall to test the set up; plugged wire harness into new tach and cranked engine before fully installing into console. The tach registered power (needle moved from resting to '0') but did not register the signal from engine.

I have an Evinrude E70TLCRD (70HP, 1984).

On this motor what sends the signal to the tach? The rectifier or stator?

Thank you for the help!

 

[Joe Reeves]

Re: Rectifier or Stator sends signal to Tachometer

The stator sends the signal.

On the models that have a water cooled voltage regulator/rectifier assembly, the signal still comes from the stator but is fed thru the reg/rec assy. In this case, a faulty reg/rec assy will interrupt the signal and cause the tach to malfunction.

 

[hidef]

Re: Rectifier or Stator sends signal to Tachometer

The Tachometer signal is the grey wire. It is tied directly to the yellow/grey wire coming from the stator. See attached.

http://www.maxrules.com/graphics/omc/wiring/78-84_3-CYL_EL.jpg

Make sure your pulse on the Tach is set correctly I believe it is 6 for your engine.

 

[Parachute Adams]

Re: Rectifier or Stator sends signal to Tachometer

I only have a rectifier, no reg/rec on this motor.

So it seems that my stator is bad since tach is not registering a signal?

I have the correct pulse setting on tach.

 

[Parachute Adams]

Re: Rectifier or Stator sends signal to Tachometer

So it goes:

Stator to rectifier back to stator then to tach?

Would a bad rectifier and good stator result in no signal at tach?

Or, if there is no signal at tach does this mean a bad stator regardless of rectifier condition?

Thanks for clearing all this up for me; I'm getting a grasp on it.

Just want to get my tach working as itsmtblast step on boat project.

 

[hidef]

Re: Rectifier or Stator sends signal to Tachometer

There is a jumper between the yellow/grey and the grey wire. Look at the diagram. The pulse doesn't go through the rectifier. Have you checked to see if the rectifier is putting out any voltage. If the system is charging the stator is good. Have you checked the wire to make sure it is good and that the connections are clean and tight?

 

[Joe Reeves]

Re: Rectifier or Stator sends signal to Tachometer

I only have a rectifier, no reg/rec on this motor.

So it seems that my stator is bad since tach is not registering a signal?

Not necessarily.... A shorted rectifier will interfere with the stator's operation which could affect the tachometer. Before even thinking about replacing the stator, test the rectifier as follows:

(Small Rectifier Test)
(J. Reeves)

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.

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.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

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.

 

[Parachute Adams]

Re: Rectifier or Stator sends signal to Tachometer

Thanks for the info; I got a replacement rectifier as I figured the current is faulty (who knows how old the current rectifier is!)

I am taking my boat in to have the water pump and thermostat replaced; has been several years since they have been serviced.
I will have them install the rectifier as well.

I think I will have them test the stator while its in their hands as well; do you think I should have them test the stator? Or would that be a waste of money? Or should I just have them replace the rectifier; and I test the tach when I get the boat back, hoping that all is sound?

I don't have any reason to think the stator is bad other than the lack of signal to tach; which mainly points to the rectifier.

Thanks again for all the info.