Rectifier, Alternator - electrickery

[skulkerboyo]

So I've had an ongoing charging issue that I was discussing here
growell.proboards.com/index.cgi?action=display&board=tech&thread=1807&page=2

I did a lot of fiddling and testing last night and I think I've got it nailed ot the alternator

From the battery at idle I get a decent voltage - I rev it to 3000 it pretty much stays the same? Light on it drops a bit and then rev it pretty much stays the same. Can jump in either direction

My frst thought was the rectifier - When I tested the points on the rectifier it was weird - the voltage dropped when I revved it - my mate said "is your alternator wired backwards" - I laughed then thought hang on . .. . . .

I tested resistance between the yellow wires and ground an dit was between 0.2 and 0.5

I think I'm looking at a rectifier problem - I did a few other little tests from the book but as ong as I'm not completely useless with a multimeter I'm fairly sure it's alternator trouble


The interesting bit is the engine is from a 600 but the rest of the bike is from a 1995 650 - is there a wiring problem to the alternator? If I replace teh alternator with one from the 600 will it experience the same issues or can I just get the one from any ntv? Trying to figure out my next move - I'd like ot try rewiring from the alterntor first but not sure what should be wired where. Am I right in thinking that at the connector block it doesn;t matter which wire yellow wire contacts which as the all do the same? What to do what to do

Really want to get this done this weekend

[realnutter]

At the connector block it doesn't matter which yellow wire goes where....

You measured between the yellow wires and ground, and got 0.5 ohms??? this was with the connector block connected?

If you unplugged the 3 way connector with the 3 yellows.. and measured from each one to earth you should see infinite resistance...

Any other result indicates a short circuit in the alternator windings...

Another test you can do is to measure the AC voltage across any two yellows with the engine running - and the connector unplugged!

You should get in the region of 80 volts ac across any pair....

If you do, and resistance to ground is infinite, then the alternator is ok....

[skulkerboyo]

Hi
It wasn't with the block connected - What does that mean then? Not my strong point electrics

When I measured to earth again the block was disconnected too

I've removed the connector and crimped the yellow cables so it'll be a pain testing the voltage accross them - will it effect the reading if they are connected as I can get to the metal.

So it looks like the rectifier isn't the issue then?

[groovylee]

simply put, if you take either of the wires coming from the alternator windings, and connect your meter between that and an earth point, you should get a massive resistance/infinite reading. anything less than that, and you have a short to earth. look for chafed through cables going through the casing. if there is a problem with the stator windings, i have spares for testing purposes. i wont be at the garage for another week, but when i do, i'll take some readings for you to compare to

[skulkerboyo]

I've managed to convince myself it's the alternator so have ordered a new (used) one in case plus gasket. Should be able to just bolt the bugger in

How much oil should spill out of the case when I open it?

I hope it cures my woes- I really don't fancy doing much more fault finding after this. Electrics really aren't my strong point - I even struggle with the multimeter!!

[groovylee]

skulker you silly beggar, i have 2 spares sat at home. you could have had one for postage

[skulkerboyo]

Ah bugger - I'll ask about here next time - I'm not used to such a helpful community - I work in I.T. and most of the forums I go on are very matter of fact etc

If it isn't the alternator as it turns out you don't have a spare rectifier?

I'll hopefully install the alternator this weekend. Moved house this weekend and the gasket didn't arrive in time anyway.

Once electrics are sorted it's on to brakes then cosmetics

Got an odd clicky noise from the rear end when turning too? Don't think I was sold a duffer but it certainly is presenting more problems as time goes on

I'm considering taking out the stator and wiring and plonking it straight in the old case as the case it came with is a bit manky

Do I need ot be aware of any wiring differences. As I stated before it's the 600 engine in the 650 frame - shouldn't make adifference logically especially as my new alternator is from a 600.

Just after a sanity check

Man, I love you guys!

[skulkerboyo]

Cheers, be good to know what is considered massive resistance

Much oil gonna fall out when I open it?

[groovylee]

on your meter it should either throw a wobbly, i.e too high a number to display, or be in the order of 10s of thousands at the very least i'd have thought. certainly thousands of ohms, not hundreds

not sure on oil, you could always tip the bike right over and support it to try to minimise it?

oh, and a spare rectifier or 3 i have. cant guarantee the state of them, but i will try to compare them and get one over to you. pm me your address and i'll pop it in the post

good luck.

[skulkerboyo]

Thanks Groovy - I'll drop the alternator in first and if it annoyingly isnt that then I'll get back to you with my address. Hopefully I'll get time to get it all done this weekend - just been drafted into the welsh three peaks and have to go up a mountain early on saturday. Loooooong weekend

[skulkerboyo]

Didn't get chance this weekend - a combination of sunshine and lack of space