Stator wires AC voltage test

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Rgus
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Stator wires AC voltage test

Postby Rgus » Sun May 24, 2020 3:23 pm

I have researched and I am still confused about a charging issue. All ohm tests pass on stator wires, rotor passes ohm tests, reg-rectifier passes diode tests.

My questions: Is it possible to test for AC voltage on the yellow stator wires while disconnected at plug from regulator-rectifier? Must the key switch be on to get 12 volts dc at stator brushes? Any info on testing brushes or stator would be greatly appreciated. I have an 81 cb650 custom which is not charging the battery.

Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Mon May 25, 2020 10:02 pm

Here is the stator plug. I only get less than one volt AC on yellow wires with bike running.

honda plug 1.jpg
honda plug 1.jpg (103.57 KiB) Viewed 4164 times
Last edited by Rgus on Tue May 26, 2020 9:02 pm, edited 1 time in total.

Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Mon May 25, 2020 10:14 pm

So, the AC voltage test on yellow wires at stator plug will not work (disconnected) because the black and white wires need to send voltage (from regulator) to stator brushes. Hope I am thinking correctly on this. Thank you for the info Volker.

I saw youtube videos of folks testing yellow leads for AC (disconnected) but they were just 3 wire plugs.
Last edited by Rgus on Tue May 26, 2020 9:19 pm, edited 1 time in total.

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Tue May 26, 2020 1:57 am

Rgus wrote: I only get less than one volt AC on yellow wires with bike running.

Basically you can disconnect the (black and white) rotor cables from the regulator and use them to supply 12V DC directly to the rotor brushes. No need to use the bike battery or care for polarity as this circuit does not use the frame as ground. At least as long as rotor windings are are not shorted to ground so better check for high resistance vs. bike frame/ground before you try this.
This way you should get full - not regulated - charging power and see some tens of AC volts between each pair of the three yellow cables. This would mean your regulator does not work properly now. If however your AC voltage is still that low rotor or stator is gone. If you should have a nice AC voltage between each pair of the three yellow cables even when connected to the regulator but it still does not charge on the DC side it is probably a regulator problem, too.
Combinations of defective parts seem possible, too, as here are reports that a shorted rotor may fry a regulator or vice versa.

Can't see a picture but I hope that already helps.
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Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Thu May 28, 2020 6:32 pm

Finally got chance to test stator yellow wires for AC volts again after sending power on black and white wires from battery-- not hooked to regulator. I do have 10 volts AC on each yellow pair at idle and it goes up with rpms. Thinking I will try new regulator next???

Also I found this info from the web page here: http://www.cb750c.com/publicdocs/chargi ... ystem.html I have not tried this yet.

"Rotor voltage with Regulator Bypassed --- measure DC volts between black and white wire on Alt/Stator connector. @ idle

How to Bypass the Regulator - However, before bypassing the regulator, make sure the field coil (rotor) isn't shorted. (You already did that, right? )
Leave the alternator connector coupled, and insert an unwound large paper clip into the connector at the WHITE wire location. Run a jumper wire from the paper clip to the battery's NEGATIVE terminal. Now repeat the charge amps test, but this time, DO NOT EXCEED 3000 RPM, the voltage could go dangerously high. Also do not let it run long like this. - If the alternator starts charging, the regulator is likely the problem. This effectively bypasses the regulator and makes the charging system produce full unregulated output. If everything but the regulator is working the voltage could go quite high, so don’t rev too high, and don’t do it for long."

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Fri May 29, 2020 1:23 am

Meanwhile I can see the picture. :)

Rgus wrote:Finally got chance to test stator yellow wires for AC volts again after sending power on black and white wires from battery-- not hooked to regulator. I do have 10 volts AC on each yellow pair at idle and it goes up with rpms.

From this I would guess that your stator is all right and your rotor at least still does something that might be enough or not as this is a measurement without load. You probably will need some 30V AC or so at 3000rpm to make powerful 14.xV DC of it.

You could also make a test with realistic load by connecting a headlight bulb between two yellows. But be careful with the throttle in this case and stop if you have a bright light.

Rgus wrote:Thinking I will try new regulator next???

Not yet. First:

Rgus wrote:--- measure DC volts between black and white wire on Alt/Stator connector. @ idle


Try this with the alternator plug connected and the engine running and see if it comes close to 12V DC. Also check AC voltages then.
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Re: Stator wires AC voltage test

Postby Rgus » Sat Jun 13, 2020 7:31 pm

Thank your for helping Volker. Sorry for late reply (I am an "essential employee" and have been working too much) Plus, I did learn how to post forum pics now :)

I finally measured DC voltage off stator plug black and white wires at idle (every thing connected -headlight on). I only get 10 VDC. I also checked voltage at stator brushes (key on) only 10 VDC at brushes. Stator yellow wires at idle (everything connected) were only 9 to 10 VAC and did not go up much with rpms under load. Note, I did have to replace my rotor as old one was only 1 ohm between rings. New rotor is 5 ohms.

My battery does seem to stay at 12.7 VDC after trickle charging with charger. But it does drop to 12V DC as bike is running under load. Still not charging???

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Tue Jun 16, 2020 12:57 am

10V DC between black and white seems low for good charging. From the list in your link above I would still try:
Check regulator - reference/rotor supply - measure DC volts at black wire to green wire on small r/r connector (14.4VDC)

Here you should see your present battery voltage. If not, there is some cable or contact issue that provides a wrong reference to the regulator and it does not know what to do.
Otherwise probably the regulator does not work properly. To be sure, you still can try the charge test with 12V directly to the brushes before you get another regulator.
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Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Tue Jun 16, 2020 9:06 pm

Thank you Volker. I will try a few more things. I am going to get this working somehow-- some way! Then, I will post what fixed the charging problem to possibly help someone else in the future.

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Re: Stator wires AC voltage test

Postby Rgus » Wed Jul 01, 2020 1:21 pm

OK, I bought a new battery. I wanted to be sure it was not the battery not taking a charge. Anyway, I get half a Volt DC less than battery voltage at black to green wire (small rectifier connector).

Also, I tested AC volts at the yellow stator wires again (connected to regulator). AC volts are 10 and do not increase with rpm much unless I disconnect the large connector and send battery voltage directly on the Black and White stator wires. I have checked continuity on black and white wires to brushes and wires are good.

Lastly, I did a parasitic DC amp draw test (passed) and also checked key on--engine not started, amp draw and got 7 amps. Not sure if 7 amps is normal draw with headlight and running lights on?

I am thinking bad reg/rectifier since I get plenty AC volts from stator when large connector is not connected to regulator/rectifier???

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Thu Jul 02, 2020 12:43 am

A sign for a weak battery is that it won't start the engine when cold although it still cranks very fine when hot.

12V x 7A = 84 Watts sound realistic with all the lights and ignition on.

Rgus wrote: I am thinking bad reg/rectifier since I get plenty AC volts from stator when large connector is not connected to regulator/rectifier???

As stated above, if you want to know if there is power behind this open circuit AC voltages, connenct a 12V (headlight) bulb between two yellows.
I agree that most probably this is a regulator issue.
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Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Sun Jul 12, 2020 8:34 pm

Finally got to do some more testing on my cb650 charging issue this weekend. Well, I bit the bullet and purchased a "Ricks" regulator off ebay. Guess what? Still no charging :(

I did do some more troubleshooting. I followed wiring diagram (regulator small connector- black wire) and checked connections at key ignition switch, and starter/stop switch. Also checked frame ground.

As stated above, if you want to know if there is power behind this open circuit AC voltages, connenct a 12V (headlight) bulb between two yellows.
I agree that most probably this is a regulator issue.




I took the headlight bulb and connected it between yellows with regulator hooked up. Even though the AC volts on yellows was 10VAC, the headlight bulb lit on all pairs. It was a bright light also. I did not know you could get a DC lamp to light on AC volts??? Any more suggestions would be greatly appreciated. I am going to continue to read and figure this out hopefully :D

Shoot, I just reread your question. Did you mean to see if headlight lit without the yellows connected to regulator? "open circuit"?

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Tue Jul 14, 2020 2:23 am

Looks like your rotor and stator passed the load test.

Did the brightness of the bulb depend on rpms? If not, your regulator probably works somehow but gets a wrong reference or does not evaluate a proper reference properly.

If yes, possibly the rectifier inside the RR is gone. You may try an AC measurement at the DC output side of the RR. I would expect below 1V AC there.

But I am still unsure if I understand what your regulator does.

Rgus wrote: Anyway, I get half a Volt DC less than battery voltage at black to green wire (small rectifier connector)

Now it would be interesting to compare that to the red/white cable from the regulator vs. battery voltage, too.
Best both voltages at idle and ~3000rpm.

DC voltage drop between red/white and battery "+" should be low with regard to charging and reference.
If you have a voltage drop there, check the connectors at the starter solenoid and the main fuse.



Rgus wrote: Shoot, I just reread your question. Did you mean to see if headlight lit without the yellows connected to regulator? "open circuit"?

That was the initial idea but if it works like that it is fine, too. Provided that you had no light with the ignition on but the engine still not running (which could mean the RR rectifier part is gone then).
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forum links to common technical issues

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Rgus
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Re: Stator wires AC voltage test

Postby Rgus » Sat Jul 25, 2020 7:14 pm

Now it would be interesting to compare that to the red/white cable from the regulator vs. battery voltage, too.
Best both voltages at idle and ~3000rpm


So I checked the red/white and black (small rectifier connecter) wires again. I also did voltage drop tests (red meter lead to battery positive--black meter lead to rectifier wires) Red/white has no voltage drop and is battery voltage at idle---it does increase half volt as rpms goes up. Black wire has 0.5 volt voltage drop, and is half volt less than battery voltage at idle and goes up almost a volt when rpm increased.

Back to basics: Question about the charging amps test. Anyone know why the charging amps test works (amps increase with rpm) but dc voltages do not increase much at battery? I did the amps test across the main fuse set to DC amps. It started out negative amps but increased to a respectable 7 amps as rpm is increased. The "breakeven" zero amps reading is about 2300 rpms and goes up with throttle. But my battery still hangs around 12 volts?

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Volker_P
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Re: Stator wires AC voltage test

Postby Volker_P » Tue Jul 28, 2020 1:14 am

If current direction at the main fuse reverses with rpms this means your charging system now does its job. Congratulations! :)

The battery voltage will first increase slowly when you have a good but quite discharged battery. 7 amps @ 12V sounds like your battery really needs and gets charge. So far nothing to worry for me.
I would measure battery voltage at a fixed rpm level, go riding for a few miles and measure battery voltage again at the same rpm level afterwards.

If voltage should still drop during riding either the battery has a problem or something inside the starter solenoid is shorted.
I think the solenoid should be feelable hot in such case after a short ride. Time to open and clean it out then.
You may disconnect the cable to the starter and check for a difference in your battery voltage (should make no difference).
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum


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