Rectifier Regulator going bad

"Okay, boat & motor are 11

"Okay, boat & motor are 11yrs old. The original tach would only rev to 1400 or so. My mechanic said it was likely the tach itself, b/c it appeared to be getting the signal from the motor (I believe he said rectifier / regulator sends the signal).

So, I headed to Ebay and found an identical tach from a surplus store. I installed it and it too is only reading 1400-ish. It is accurate at idle and if I slowly accelerate - I've almost gotten it to 2000rpm, but nothing above that - it drops to 0. If I'm idling and gun it, it drops to 0.

So, is it likely my rectifier / regulator? Is it possible for the signal to drop off like that? What exactly is it? If so, could it also be doing some harm to the motor? The motor has plenty of punch, but definitely isn't as fast as it use to be - before my rebuild I could do 42mph w/ just me & 1/4 tank of gas. After rebuild & break-in I did 38mph w/ me & a friend and a full tank. The other day I could only do 34mph w/ me and 1/2 tank. (compression is fine - 122, 125, 130, 130)"

"reg/rect-----..by the way...j

"reg/rect-----..by the way...just a suggestion....in my opinion,...i would not by any used,elect devices,w/out a warranty..for an outboard...on ebay.----> tach from a surplus store.= prob used,maybe defective."

"u can buy,quality,sierra,cdi

"u can buy,quality,sierra,cdi electronics,right on this site. NEW."

"Sorry, should have specified

"Sorry, should have specified - tach was brand new. This is actually the second one though - first one was dead in the box, so they sent me a second and a return label for the first. The second one is the one that is installed now and although isn't working properly, it is MUCH smoother than the original 11y old tach. So, I've eliminated the tach. Yeah, I will be ordering off of this site if need be - are the 3rd party vendors (CDI, Sierra, Mallory) recommended? If one isn't, PLEASE specify!! Price goes like this: Mallory, Sierra, CDI, OMC. If it were my car, I wouldn't hesitate - go to AutoZone, etc all the time. With an outboard though, I'm not sure if it's one of the "get what you paid for" things......"

"Your tach works off an AC pul

"Your tach works off an AC pulse from the stator. You can take the rectifier/regulator out and throw it away and as long as the tach is connected to one of the yellow wires coming from the stator, it will work (if the stator is good). The connection for the tach is made at the rectifier/regulator simply because it is a convenient place to make it. The 2 yellow wires coming from the stator feed a full wave bridge rectifier consisting of 4 (sometimes 6) diodes. It depends on which diode gets damaged whether it will affect the tach or not. Bottom line is the charging system can be damaged but the tach still work. When in doubt, test your rectifier/regulator according to your manual."

"If You have a multimeter with

"If You have a multimeter with AC reading would do, with Hz reading even better.
Hook the + to the gray wire, - to any black/ground. Run the engine and check if You loose signal. If signal gets lost, Your regulator is defective."

"When you say signal lost, I&#

"When you say signal lost, I'm assuming you mean when the motor is revved? Also, which AC setting for my multimeter? I'm not sure what kinda voltage we're talking about here - figure it can't be too high though. Thanks for the info - I will test it out one day after work - probably have to wait till Wed, but will post the results."

Check the instructions that ca

Check the instructions that came with your new TAC you have to set it base on the Model of engine you have. 6 pole or 12 pole look carefully at the back of the TAC you will see the setting screw ..

"Yup, 6 pole - already set. In

"Yup, 6 pole - already set. Installation was simple - plug the 8 pin harness in and the dial had two options - 5 or 6 - and 6 was already selected - as it should be (it is an exact replacement for stock). I appreciate the input though - wouldn't have been the first time I overlooked the obvious!!"

"Hey IBNFISHN,

I am very gl

"Hey IBNFISHN,

I am very glad that you posted as you did. I was wondering how you know it is a full wave rectifier?
Did you get ahold of the specs, or did you tear into a bad reg/rect...
Do you have the circuit design schematic?
Anything else interesting in there? Like, is there an IC for charge current limiting, or is it all made with discreet electronic components...
Anything else you know will sure be interesting."

"Probably not this time, but I

"Probably not this time, but I had a very wierd problem like this which resolved in an unexpected way. problem was the tach worked at first but after a few minutes it fell off to very low. At the same time the batt volts fell from 14.5 to 13v and change. never seen before.
I changed everything with no effect.
What it was was like this;-

1) I have no-maintainance batteries.
2) For the first time I had used a solar to maintain the batts when not in use.

So, the batts were higher than ever arose before in normal service.
So high that the reg cut off totally and the ac output was not enough to properly work the tach.
After a few trips ( and no solar) the situation returned to normAL. No trouble since.
I read in the instructions for the new reg., that maintainance -free batts are verboten!
(Guess voltage can rise too high as in this case)
I now own a spare reg and power pack."

"Doug, there is a schematic of

"Doug, there is a schematic of one in one of my manuals but not sure which. I have made my own using 4 ECG116 diodes. A lot of people use a 25 amp full wave bridge rectifier available at Radio Shack for about 3 bucks. I haven't tried one my self but see no reason for it not to work."

"Thanks IBN,
I always wondere

"Thanks IBN,
I always wondered whether it was full wave or half wave rectified. Makes a diff when and if you want to mathematically calculate voltages, etc. I am trying to reverse engineer the charging system in my mind so that I can make a better diagnosis when charging system probs occur.

Thanks again."

"(Testing Tachometer With

"(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Remove that gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"