Mercury Rectifier

[mulliganmagic]

I just found out that I have to replace the rectifier. It was old and I broke a thread off of it trying to remove a wire. But I would like to know how to wire the tachometer straight to this rectifier since I'm replacing this little gizmo any way. My tachometer has three places for wires and I think that it's a mid 80s quicksilver tach.

 

[WillyBWright]

Re: Mercury Rectifier

There may be four. G or GND would be negative (black), I or IGN would be keyed positive (purple), S or SND would be the tach signal from the alternator (gray), and a fourth (blue) for the light. The gray wire attaches to either yellow lead on the rectifier, it doesn't matter which.<br /><br />Oops, is this for the 70Hp? I think it's still the same, but the tach lead might be brown.

 

[mulliganmagic]

Re: Mercury Rectifier

Sorry yes this is for my 1977 Mercury 70hp. My rectifier has three terminals and my tach does have a GND and a SND and I'm not sure what else I don't have it with me. It does have a light, but my moter has been partially rewired so all of the wires around the rectifier are red. Can you explain in more detail how to wire the tachometer like what wire comes from where (I've never done much wiring but I can learn).

 

[Chris1956]

Re: Mercury Rectifier

MM, You can get a replacement rectifier at a local Radio Shack for under $5. Buy the 25Amp full wave bridge rectivier. You will also need to convert the engines ring terminals to female spade terminals, and connect the negative pole of the rectifier to ground (engine block). <br /><br />The Tach sender connection should be connected to one of the two yellow stator wires(this is an ac signal). Normally the three prong plug made by Mercury attaches from the front of the merc control to the tachometer. This plug supplies +12V, Ground and Stator signal to the tach.

 

[mulliganmagic]

Re: Mercury Rectifier

I already bought the original factory rectifier at NAPA for $40 so I'm good with that. I do have a question though how how would I connect the tach to the starter would I have to splice one of the wires or take it off where the wire connects to the startor and add a tach wire? Also where does the ground wire go? A full description of how to wire a tach would help because I'm trying to wire it without buying the adaptor (or if the adaptor is worth the $30 bucks instead of the trouble let me know).

 

[Chris1956]

Re: Mercury Rectifier

MM, My 1977 Merc has a wire that runs from the verticle slot in the connector on the front of the control, thru the engine wiring harness and connects to either of the two stator wires at the rectifier. This should be connected to the sender pole on the tach. It is brown in color. <br /><br />You can make a little wiring harness to replace the $30 merc adapter using three male spade terminals, and three pieces of wire and three ring terminals. The ground wire for the tach is the bottom horizontal slot on the connector (I think) and the top horizontal slot is plus 12 volts. The plus 12 Volt wire goes on the tach's ignition connection and the ground on the control is connected to the ground pole of the tach.