2nd blown rectifier

[dpfrost]

To all that can help!!!!!<br /><br />I have a '87 135hp merc. The tach was not working and the battery was not charging. I narrowed it down to the rectifier being bad all continuity check showed nothing. Replaced with new one, all continuity checks were good. Went and run the boat for a little bit today to see if tach and charging were ok. NOTHING. Same as the first. Check continuity again on 2nd rectifier and it showed nothing. What kepts blowing the rectifier. I check continuity on the 2 yellow stator wires and they check out ok. Any known advise would greatly be appriciated

 

[Silvertip]

Re: 2nd blown rectifier

If you have a battery switch and are messing with it with the engine running, that will kill a rectifier. If you have no battery or bad battery connections (check/clean both ends) that will also kill it. If the output of the rectifier is not connected to the battery (or solenoid) that's the same as having no battery or bad cables and will also kill it. Lots to look at here.

 

[ricksrster]

Re: 2nd blown rectifier

Check the red wire from the rectifier. make sure it is clean and tight. Check your internal wiring harness for brittle or missing insulation or shorts.Do the same with the harness that goes to the controls. Make sure your battery's cable connections are clean and tight. It sounds like the current isn't making it from the rectifier to the battery. That will burn out a rectifier.

 

[dpfrost]

Re: 2nd blown rectifier

thanks guys out the door now to look over everything. will kept you posted

 

[dpfrost]

Re: 2nd blown rectifier

would a bad voltage regulator kill the rectifier?

 

[Silvertip]

Re: 2nd blown rectifier

If it leaves the output of the rectifier with an open circuit -- you bet it will.

 

[MercFan]

Re: 2nd blown rectifier

I had a problem on my boat that blew rectifiers. The i6s of the 70s and 80 didn't come standard with voltage regulators, so if you have one it was fitted later.<br /><br />My problem was that my battery was too small (or maybe a bit old) and could absorb the extra voltage being pumped into it. So the solution was 2 fold.<br /><br />First I went with a dual parallel rectier setup. I've used this setup before in a power supply in my house. I'm including a pic of my rectifier setup<br />

<br /><br />The second part of the solution was adding a second battery to the other side of the boat and also hooking that in parallel to the first one.<br /><br />Now my voltage that used to go all the way to 19V, never goes above 14V.<br /><br />PS. I blew 2 tach's before doing this, so your tach might be history.

 

[dpfrost]

Re: 2nd blown rectifier

hey mercfan <br /><br />thanks for the advise. my tach works on when the motor is idolling. but when i blast off it goes to 0 then bounces all over the place. but never steady in one place. is there a way to check for a blown or bad tach?

 

[ricksrster]

Re: 2nd blown rectifier

Check tach set up. the tach should be set up to 12pole / 6 pulse. Some tachs will have 6P on selecter switch on back of tach. Check the wire connections on the back of the tack. Key on ignion wire connects to ign. post on tach. Awire from you lights go to lights. signal wire from rectifier connects to signal post on tach. Then of course ground. Make sure wires are not loose or shorting out.

 

[ricksrster]

Re: 2nd blown rectifier

check your voltage at ignition post and make sure it is between 12 and 16v. If eveything checks out, you might have a bad tach.