Squidley Posted June 30, 2011 Share #1 Posted June 30, 2011 Just looking to hear from some of the electrical gurus out here. Monkey Boy's '90 is having a charging issue and I went to check it out today. I did an AC voltage test on the stator and wanted to make sure I did it correctly. Bike running, negative lead of multimeter directly on the negative battery post. Tested each leg of the 3 wires and came up with 4 VAC on 1, 6.1 VAC on the 2nd and 11 VAC on the 3rd. In my head this is a bad stator that needs to be replaced, I'm just wanting to confirm this with more educated electrical brains. The battery was fully charged and installed right before I did the test....give me your opinions. Link to comment Share on other sites More sharing options...
MiCarl Posted June 30, 2011 Share #2 Posted June 30, 2011 Well, I don't think the manual has an AC voltage check, but if you're doing one you should be doing it between pairs of stator wires - not to the battery. You should check resistance between each pair of stator leads. I don't recall the spec but anything between .5 and 1 ohm is probably ok. Then check each resistance from each lead to ground - should be infinite. Link to comment Share on other sites More sharing options...
frankd Posted June 30, 2011 Share #3 Posted June 30, 2011 Squidley, I agree with Carl. The first test I do is from any of the 3 white stator wires to ground---should be infinite. I look at the stator to regulator plug (both halves) and make sure none of the leads have burnt. If one has been hot, cut the plug off and twist, solder, and then tape theleads. If the stator and plug are good, the regulator would be the next thing to look at. You can measure all 6 diodes by connecting an ohmeter (preferable an analog meter, but if you use a digital make sure you use the diode test position) between 1 of the white leads going into the regulator to the battery cable plus then the negative terminals. Each white wire needs to be tested and all 3 should test the same. You should see a diode between each white regulator wire and plus (red) and negative (black) battery terminals. You can have the battery disconnected for this test. To test the diodes, hook the ohmenter up one way and then reverse the leads. One way should conduct, the other should measure open. I did have a diode open up on a first gen. Judging by your readings to ground, you'll probably find the stator is grounded. Frank D. Link to comment Share on other sites More sharing options...
MiCarl Posted June 30, 2011 Share #4 Posted June 30, 2011 Some more thoughts for you, if my brain weren't so old they would have made it to the original post.... I have a friend whose stator passed the resistance tests but was only putting out 2-3VAC on the leads. A new stator solved his problem. My only guess is that the insulation on the windings can break down but not show as shorted with the low voltages from the meter. The higher voltages created by a running engine cause current to "leak" through the insulation. The reason I didn't meter the AC output of my stator for him is I permanently soldered it to the leads from the regulator/rectifier. We did probe the wires though and got something in the neighborhood of 12VAC at idle. To me that seemed like a reasonable value because having it connected to the regulator/rectifier means it's driving the bike electrical system. I think a disconnected stator should show at least 15VAC at idle and more than 20VAC at speed. If you see differences between your 3 readings that probably means the stator is bad. Link to comment Share on other sites More sharing options...
BradT Posted June 30, 2011 Share #5 Posted June 30, 2011 Dam Electrical issues and then the stupid meters HAHA. I hate electrical but checking the stator as mentioned above is not that bad but diodes and resistors get me worked up. Good luck Squid, Brad Link to comment Share on other sites More sharing options...
bongobobny Posted June 30, 2011 Share #6 Posted June 30, 2011 And I just gave a spare stator away at MD!! Yah, sounds like one of the windings bit the dust. It is a Wye configuration, and as long as you had the stator unplugged you should get an equal AC voltage between any combination of wires. A statore is an AC generator, the rotor is just a magnet that goes round and round and as it does the magnetic lines of force produce an electrical current as they pass the wires. The north pole makes the electricity go one direction, and the south pole makes the electricity go the opposite direction, hence ALTERNATING Current, not Direct current. Changing the AC to DC is the job of the rregulator... Link to comment Share on other sites More sharing options...
Squidley Posted June 30, 2011 Author Share #7 Posted June 30, 2011 Just to clarify a bit more, I did do a resistance test between the 3 leads with the bike not running. In every combination (I did 9) and it all came back at .9, this at 1st lead me to believe that it might be good. When I had it unplugged at the main harness connector (plug is in great shape with dilectric grease still in it) and checked it while running, the variations of AC Volts is what spoke to me in the thought that something wasn't right. I will also check the wiring at the Regulator, but I'm still leaning towards a toast stator. I had a good spare stator that I pulled out of my '89 and have given it to Monkey Boy to see if he can get it rewound while he is up in Michigan on vacation. Thanks for all the input guys, do appreciate it Link to comment Share on other sites More sharing options...
Yammer Dan Posted June 30, 2011 Share #8 Posted June 30, 2011 And I just gave a spare stator away at MD!! Yah, sounds like one of the windings bit the dust. It is a Wye configuration, and as long as you had the stator unplugged you should get an equal AC voltage between any combination of wires. A statore is an AC generator, the rotor is just a magnet that goes round and round and as it does the magnetic lines of force produce an electrical current as they pass the wires. The north pole makes the electricity go one direction, and the south pole makes the electricity go the opposite direction, hence ALTERNATING Current, not Direct current. Changing the AC to DC is the job of the rregulator... Explained til even I think I get it. SHUT UP Quacker!! Unplug the thing check each lead to ground and readings should be close to same?? Should show at least 12 volts Alternating Current on each?? I just found out the other day my oldest son is very good playing with a Multi-Meter. Time for him to teach me....Electrical things have always been my weakness. Link to comment Share on other sites More sharing options...
bkuhr Posted June 30, 2011 Share #9 Posted June 30, 2011 On my 750 book called for .4 ohms between the stator leads, I read .2 ohms and thought just tolerance error, but turns out it was bad and and replacement repaired the problem. Link to comment Share on other sites More sharing options...
Bvinson Posted June 30, 2011 Share #10 Posted June 30, 2011 (edited) Brad, For some reason the forum will not let me attach a document to send you. Follow the link below to a post I made a few years back. It is a good flow chart for checking for electrical problems, You will need to scroll down a little. Bill http://www.venturerider.org/forum/showthread.php?t=25062 Edited June 30, 2011 by Bvinson Link to comment Share on other sites More sharing options...
Monty Posted June 30, 2011 Share #11 Posted June 30, 2011 Brad...use this. http://www.mbraonline.com/uploads/Checking_your_Stator_Process_chart2.pdf Link to comment Share on other sites More sharing options...
Squidley Posted June 30, 2011 Author Share #12 Posted June 30, 2011 Brad...use this. http://www.mbraonline.com/uploads/Checking_your_Stator_Process_chart2.pdf According to the chart, (Bill Vinson emailed me the same one, thanks Bill) it states if the 3 AC volt readings aren't equal then the stator is bad. Thats what I am leaning towards, Thank you all again for your input on this Link to comment Share on other sites More sharing options...
bongobobny Posted June 30, 2011 Share #13 Posted June 30, 2011 Explained til even I think I get it. SHUT UP Quacker!! Unplug the thing check each lead to ground and readings should be close to same?? Should show at least 12 volts Alternating Current on each?? I just found out the other day my oldest son is very good playing with a Multi-Meter. Time for him to teach me....Electrical things have always been my weakness.no, between any 2 wires. Each combination should give you about the same AC voltage. Can't say if I ever tried between the wires and ground because unplugged they are not referenced to ground, just each other. Draw a "Y" and make each leg a coil. All 3 coils are commoned at the center and it should not be at ground. If any of the wires read asnything to ground the winding is shorted to ground and the stator is toast. There should be a very high resistance to ground in the order of thousands of millions of ohms. You need a special "Hipot" tester to read this resistance. Even though a winding is not directly shorted to ground, if it's insulation rresistance is low then the stator is also toast as the output AC for that winding will be lower than it should be, similar to what the output voltage will be if some of the winding is shorted out to itself... Link to comment Share on other sites More sharing options...
Squidley Posted July 1, 2011 Author Share #14 Posted July 1, 2011 You know you just fried his brain there Bobby Fried part of mine too Link to comment Share on other sites More sharing options...
bkuhr Posted July 1, 2011 Share #15 Posted July 1, 2011 Just to clarify a bit more, I did do a resistance test between the 3 leads with the bike not running. In every combination (I did 9) and it all came back at .9, Just to get your "actual" ohms, short your meter leads to each other when on the same ohm scale you used above. This is the lead resistance and needs to be subtracted from your above .9 readings. Normal lead resistance usually .1 or .2 ohms which would put your stator at about .7, still in limits, but a cheap meter with cheap leads may be higher resistance, and could make your stator resistance too low. Link to comment Share on other sites More sharing options...
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