Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Tinkerer

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At $95 for a genuine part that could blow again I'd love someone to tell me that the motor bike rectifiers going for a few bucks on eBay will do the same job.<br /><br />I've got a 12 volt system with a 6 amp alternator on battery ignition. Basic coil and distributor motor with no CD pack. The rectifier is a three wire with two yellows coming off the stator and a red one to the battery. No separate regulator or other circuitry. <br /><br />An outboard parts supplier told me I can get rectifiers at an electronics chain for under $10 that'll do the job but they won't hold up over time, so I'm guessing that any rectifier with the right output might be OK.<br /><br />Anybody know? Or am I heading for problems if I try it?
 

Paul Moir

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

The regulator is an electronic device known as a 'Bridge Rectifier', which has four wires. The AC inputs go to the yellow wires, the + output goes to the red wire, and the - output goes to engine ground. I usually get a really hefty one (25 amps) mainly because it's easy to mount. You want to mount it so it gets some cooling - say to a reasonable piece of aluminium on the block.<br />Voltage is hardly an issue since the lowest you can get is 50V PIV. And you're dealing with less than half that.<br />I usually pay less than $3 for a bridge rectifier. If I were trying to sell you one that cost $95, I would probably say something like 'the cheap ones don't last long'. Either way you look at it, $95 will buy you an awful pile of bridge rectifiers.<br /><br /><br />Hope this helps!
 

mnw001

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Paul <br />That sounds great and I found the rectifier you mentioned for $2.32 @ Digikey.com the part number is GBJ25005DI-ND <br />So have you actually used these and do they hold up. Is there anychance of damage to the stator?
 

Xcusme

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Fishslayer....you might want to conside the GBPC series...they have spade lugs...unless you're into soldering...<br /><br />(Paul, you're killing me....now that you've let the cat outta' the bag, everyone will want one) :D :D
 

Paul Moir

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Fishslayer, I've only tried it on a Merc with a 6 amp stator. It will not work on higher current systems such as the ones that use a water cooled rectifier. Also, there is no regulation that those higher current systems require. The big buck 'rectifiers' often have regulation circuitry as well.<br />Since you don't say which system you have, and I probably am not very familiar with it anyway, I really can't advise you on your specific situation. If you wire it wrong, it is possible to damage the stator. It is far easier and far more professional, to simply replace the rectifier. <br /><br />I use a bridge rectifier like DigiKey GBPC2501DI-ND because it has more durable terminals that accept spade wire connectors.<br /><br />EDIT: Xcuseme: Ooops! :D Now we'll have to go back to selling OFC speaker wire at $100/ft.
 

seahorse5

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Just purchase a late model V4 rectifier like the one on an 88hp Johnson/Evinrude and splice the ends to fit your motor.<br /><br />They sell for half the price and are good up to 9 amp charging systems.<br /><br />They are very reliable unless you have loose or corroded battery connection, or if someone reverses polarity even for an instant.
 

Tinkerer

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Originally posted by Paul Moir:<br /> It is far easier and far more professional, to simply replace the rectifier. <br /><br />
Easy?<br /><br />Professional?<br /><br />Why would I want to start doing that sort of work after spending 40 years doing it the other way?<br /><br />Paul, seriously, thanks for the tip. I got an AU$4.95 600V 35 amp bridge rectifier from an electronics chain. The next size down looked way too small. Base and base resin are exactly the same size as the OMC one but the terminals are exposed where the OMC one has a clear resin with fake metal paint over it (I know this because I destroyed it to see what was inside.)<br /><br />Hooked it up and it's charging the battery, so the stator's still OK.<br /><br />Initially I thought it wasn't working because I was using a digital multimeter but it's fine on an analog one.<br /><br />The digital one just kept flickering around 18 something volts as best as I could see, both with the charge line from the rectifier connected to the battery and without it. I guess it's some sort of disturbance from power going to the coil that the digital meter can't even out.<br /><br />The analog one held steady and the needle rose steadily on charge.<br /><br />After switching off after maybe a minute the digital one read 13.5 volts across the battery terminals where it was 12.95 before the test.<br /><br />Am I better off using an analog meter on this old motor and, if so, why?<br /><br />Separate issue. I think I'll just get a voltmeter for the instrument panel and keep another $4.95 bridge rectifier on board and change them if it stops charging. Way cheaper than $95 each time. Or $250 if I get the original part that I was quoted today.<br /><br />Thanks again. <br /><br />P.S. About 20 years ago I bought some very, very expensive speaker wire to go with the new CD player. I don't think it worked any better than the ordinary stuff, but the salesman sure made it sound better in the shop.
 

Tinkerer

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

seahorse<br /><br />Thanks.<br /><br />I'll try the $4.95 ones for a while and see what happens. If they fail really quickly I'll need something better and your suggestion will solve the problem.
 

Paul Moir

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Tinkerer - don't get me wrong, if it was my own outboard we were talking about here, it would have the $3 rectifier in it. In fact, I would rather it that way. On the other hand, if I payed someone to fix my outboard I would expect them to replace it with an OMC or aftermarket part matching the old one. It takes some skill and responsibility to re engineer the charging system. Using a stock part pretty well absolves the mechanic. I know you were just joking, but there's other people reading this post and that's who I wrote that for.<br /><br />The stator via the rectifier generates a series of fairly high peak voltage pulses (say around 24v but it may be much higher). These pulses are 'held down' by connecting the battery. incidentally, this is the job of the regulator on higher current systems. On those the battery cannot 'hold down' the pulses, because they carry too much current for the battery to take.<br /><br />Your digital meter is seeing those stator pulses and is getting confused by them, while the analog one is smoothing them out. If you set your digital meter to AC volts and check the battery, you should be able to measure the pulses on top of the DC component.<br /><br />I expect your rectifier will last a long time. Given it's very high PIV, it shouldn't be troubled with corroded battery terminals like the stock one. The main thing is to mount it well so it can cool. Putting some heat sink grease between the bridge and whatever you mount it on would be a good idea.<br />Like any other bridge rectifier, it'll fry quick if you hook up the leads backwards though. You could fuse it (say, 15A) on the positive line to protect it if you though it was likely to be hooked up backwards though.
 

mnw001

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

Paul<br />My motor is a 79 johnny 140 it is a 6-10 amp stator and is unregulated as far as I can tell..<br /><br />Thanks
 

Paul Moir

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Re: Any alternatives to OMC rectifier for '67 Evinrude V4 60HP?

From what I'm reading, it should work fine for your outboard Fishslayer.<br />Iboats 18-5708 is a drop in replacement and sells for $30 if you want to save yourself some work. I think you can get it from NAPA autparts as well.
 
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