1996 200 Merc, Need to Test Rectifier

[ajhabbit]

How can I test the rectifier on a 1996 Mercury 200 EFI? I have a multi-meter and a very basic knowledge of the motor. <br /><br />The rectifier is in question because the tachometer is not working and I was told that the grey wire should only be putting out 5-7 volts AC. I am getting 17-20 volts AC.<br /><br />Thanks<br />Alex

 

[WillyBWright]

Re: 1996 200 Merc, Need to Test Rectifier

If the potting is greenish and clear, you can usually tell a bad one by easily visible anomalies to the circuit board. High voltage seems strange. I'd expect no signal voltage at all to a dead tach.

 

[ajhabbit]

Re: 1996 200 Merc, Need to Test Rectifier

Thanks for the reply. I just took off the rectifiers and didn't realize I should have disconnected the battery first. The outside of the rectifiers were both giving off 12 volts DC. I am thinking the rectifiers should not have voltage on the outside. Is this normal to through sparks when taking out the rectifiers? One rectifier has a green tint when looking at the circut. The one with the green tint has dark brown markings around the solder. The other rectifier looks like the board is a light brown. The middle has a dark brown cloud about the size of a fifty cent piece. The dark brown cloud kind of looks like something exploded inside. On the board under the dark brown cloud is dark brown markings. If the rectifiers are bad, where would be a good place to get an inexpensive one? Mercury's website list my rectifier for $112.00 a piece. <br /><br />Thanks Again<br />Alex

 

[Hooty]

Re: 1996 200 Merc, Need to Test Rectifier

If you've got a DVA, you might check the stator output voltage. If no DVA, use your manual and vom to check the stator windings.<br /><br />c/6<br />Hooty<br /><br />Edit- Rectifiers? It's only got one rectifier.

 

[ajhabbit]

Re: 1996 200 Merc, Need to Test Rectifier

Thanks for replies. <br /><br />I have two rectifiers, each rectifier is identical. They both have two yellow wires, two red wires and one grey. The yellow wires were connected to the stator, the red wires go into a big bundle of wires (not sure where they end up) and of course the famous grey wire goes to the tach’s send post. The part number on the side of the rectifier is 815279 -3. There is another number 3095 not sure what that is for.<br /><br />Thanks<br />Alex

 

[dilligafda]

Re: 1996 200 Merc, Need to Test Rectifier

More acurately they are regulator/rectifiers. If your tach isn't working off one, have you tried switching it to the other? Sometimes you can diagnose a failed reg/rec that way. And yes you will have battery voltage at the regulator all the time. The sensing circut for the regulator is connected to directly to the battery and will have 12VDC at all times the battery is connected. Hope this helps!

 

[WillyBWright]

Re: 1996 200 Merc, Need to Test Rectifier

One of the regulator/rectifiers is bad for sure. The one that looks like it exploded inside...a diode in the circuitry. The other may be suspect, but you might try as suggested to move the tach lead to that unit before you replace it. If the tach works, then that reg/rect is probably okay. The replacement you will be getting will look different and have a ground lead as an improvement. Hopefully it'll last longer than the original.<br /><br />Make sure your battery connections are clean and tight. Loose and corroded battery connections are the leading cause for such failures. Hooking the battery up backwards, even for a split second, is another.

 

[ajhabbit]

Re: 1996 200 Merc, Need to Test Rectifier

I realize that the regulator/rectifier has voltage at all times, but I don't think the outside of the regulator/rectifier should have voltage. The regulator/rectifier is bolted to the engine and the outside metal frame of the regulator/rectifier which the bolts go through, is reading 12.5 volts when testing between the place on the rectifier that bolts to the engine and on the engine where the regulator/rectifier bolts on. Or is this correct to have 12 volts on the outside frame of the rectifier?<br /><br />Thanks<br />Alex

 

[WillyBWright]

Re: 1996 200 Merc, Need to Test Rectifier

That's the difference between just a rectifier and a rectifier/regulator. Regulators dump the excess back to ground which is the negative half of the circuit. So if you unbolt it, it'll show voltage because it has continuity internally.

 

[ajhabbit]

Re: 1996 200 Merc, Need to Test Rectifier

So it is normal for it to through sparks when disconecting, if I didn't disconect the battery? So next time I connect or disconnect the regulatory/rectifier, I will make sure to take the positive off of the battery. I found some rectifiers on ebay, brand new for $55.00. Should I look out for bad name brands? I noticed that the one on ebay has a wire that I do not have. It looks like a purple wire. Any idea about the extra wire?<br /><br />Thanks<br />Alex

 

[WillyBWright]

Re: 1996 200 Merc, Need to Test Rectifier

I'm always real leary about electronic engine parts on eBay. Why are they selling them? Could it be because one failed and they decided to replace both and sell the old ones in the new boxes to some poor sucker? No way I'd buy such things from eBay, no mattter the price. Get a new one, get the guarantee. Buy a used one, inherit the previous owner's problem.<br /><br />The purple wire might be a ground wire. It should be black. But cameras, computer screens, etc. can skew the color. If it's a ground, it'll have a ring connector on the end.

 

[ajhabbit]

Re: 1996 200 Merc, Need to Test Rectifier

I to am also very leary of electronic parts from ebay. I know it doesn't make it right, but they are selling them through an ebay store, so I am thinking they have more than just a couple. The advertisement says brand new Mercury outboard O.E.M. Voltage regulator. O.E.M? The wire does look black and it does have a round end.<br /><br />Thanks<br />Alex

 

[gss036]

Re: 1996 200 Merc, Need to Test Rectifier

You can e-mail the seller and ask what ever questions you might have. Ask if they are a dealer,etc.

 

[dilligafda]

Re: 1996 200 Merc, Need to Test Rectifier

O.E.M. = Original Equipment Manufacturer