rectifier

[pobuda]

I have a 175 evinrude and the tach is not working right it shows 0 or below at idle and if I rev it up it will go up from there I was thinking rectifier but I checked volts at battery and it seems to be charging. my question is can I have a bad rectifier but it will still charge my battery

[Solarman]

First off, the rectifier converts the AC output of your magneto to DC output, so that the regulator can adjust the DC voltage needed to power your electrical devices, and charge your battery as it needs.

If your tach was reading correctly in the past, but isn't now, it may be dirty connections. You need to access the back of the tach, to check wire connections (clean and carefully tighten if need be), also look for a switch on back (might be under a small plug), and should be in one position (may have several), notice which position it's in, and then switch it back and forth through the other positions, returning back to it's original place (put plug back). Make sure wires are connected as before, and add water, start motor to see if that helped. Most times switching like that cleans the inside connections, putting it back in phase for your motor.

It might help to take a pic of wiring before removing tach, it could help if a wire pulls off when removing. I don't know if easy to access? But this is a common problem, and the first step I'd take, as well as checking any connections at motor/ rectifier-regulator to see if dirty/corroded?

Post back when able, let us know if that helps.

[pobuda]

rectifier

thanks for the great info i will check tach conections tomorrow. the reasons i was asking about the rectifier is because it has a dark tar like substance leaking out, and last week while fishing i tried to leave fishing spot, boat started fine but every time i gave it gas it would die, it started right back up and idled fine, after around 6 starts i finally got it going without dying and it ran fine.

[Solarman]

Ok, then yes, you should check that as well. It does sound like it may be going out?

Good luck.

[pobuda]

I tested the rectifier with a multimeter. I grounded black lead from multimeter and touched red lead from multimeter to red, yellow,and yellow with grey strip I got no reading from multimeter which was set to diode. Then I grounded red lead from multimeter and touched black lead from multimeter to red,yellow,and yellow with grey strip and still got no reading. is that a sign of a bad rectifirer.

[Solarman]

Am not sure if there's an ohms test for rectifier, but know you check magneto voltage (AC), then plug rectifier to magneto and test voltage coming out (DC). You'll have to check the manual for your motor for proper tests and results.

Good luck.

[pobuda]

ordered new rectifier today hopefully it will be here in 3 days. I will bench test the new one the same way I tested the old one and post my findings maybe it will help someone having the same problem as me

[GaryOaks]

Is this the unit with two yellow wires to a plug, one long red with a ring lug and a purple and a gray wires? Been having issues with my unit also. Bench testing is showing something weird but going to clean everything, reinstall and take voltage reading while running.

[pobuda]

yes this is the same rectifier when I bench tested mine I had no readings when I grounded the multimeter. My new one should be here tomorrow or Thursday I will post how it tests out and let you know how a new one should read. My understanding is if you test it like I mentioned above you should get a reading of 450 or so one way and nothing the other way. This means your diodes are only letting current go one way as they should. Since I had no reading either way that's what makes me think I have a bad rectifier. Also instead of grounding one side of multimeter if you hold the black lead of the multimeter on your red wire with ring lug and set multimeter to diode which is the symbol that looks like an arrow with a line running through it and then touch each yellow wire with red lead you should get a reading around 450 on each yellow wire. Then switch the leads around, red lead to red wire with ring lug and black lead to each yellow you should have no reading.

[pobuda]

unfortunately my new rectifier tested the same as my old one. might have wasted 200 bucks. im putting it on ill post results when I test on water. If anyone knows a better bench test for rectifier please let me know.

[GaryOaks]

CDI electronics does have a nice troubleshooting manual at:
ISSUU - CDI Electronics Troubleshooting Guide - 6th Edition by CDI Electronics

It covers quite a bit of different systems, it might help. I did put mine back into the motor today to try it. First three starts there was no tach or charge. The next start I had tach and charge, but it was charging at 17 to 18 VDC. The battery was already at 12.5 VDC. Two more starts with the same results and the next one with no tach or charge. The purple wire did have the battery voltage on it so it should have known to supply the tach signal and the voltage on the battery. Something very weird here also

[cyclops2]

ALL rectifiers & diodes ......MUST.....have very high resistance 1 way.
Must have very low resistance with the opposite meter polarity the other way. NO EXCEPTIONS.......electronics law !!

Your NEW ?? Is a reject from the factory. I also suggest that you.........CAREFULLY............Physically take apart each connection. ONLY doing 1 at a time. You should find a loose / corroded connection.

The Molded rectifiers normally need some THICK wheel bearing grease smeared on the surface that bolts to the engine. Not a messy squeezed out blob. It removes heat faster & increases life at WOT rpms.

Most used batteries are fully charged at 13.5 vdc. CAREFULLY CHECK THE BATTERY CELL water levels. Post back if you are not sure how much to add. Check every couple of running months.

[ttles714]

rectifier test

I think your testing procedure for the rectifier is correct.. I do not understand why the new one is giving you the same readings. I am also replacing a rectifier this weekend and did the same test with the same results and am waiting for the new regulator to arrive.