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ViragoTechForum.com XV750 (SOLVED) Help with resolving charging system issue.

#1:  (SOLVED) Help with resolving charging system issue. Author: keratos Post Posted: Wed Jun 09, 2010 3:01 pm

Hi

Just bought a XV750 Virago 1993 UK model.

Riding it home from the vendor's house and after 15 miles it cut out.

Called the AA and they tested the charging volts with the engine running. Was 12.5V.

Charged the battery which got me home.

Put the bike in my garage and grabbed hold of the alternator wires (3x white wires) at the alternator end (not the harness end).

With a multimeter, I tested each of the pairs of three wires for resistance. The resistance in each case was around 1.2ohms. The specification is 0.5ohms +/- 10%.

Checked the wiring and no obvious issues.

Could this be the stator? Only thing is the price for a stator is around 50 or so I have found to be the case. Seems rather expensive. And it could be the rotor which is even more expensive.

What options do I have?

EDIT: I also get continuity from any of the white connectors coming out of the alternator assy , to ground/earth.

Thanks


Last edited by keratos on Tue Jul 06, 2010 3:52 pm; edited 1 time in total

#2:   Author: mark75 Post Posted: Fri Jun 11, 2010 1:41 am

Howdy keratos. Welcome to VT.

have you checked the regulator/rectifier?

put VOM on the battery, @ about 3000rpm should be about 14.4 volts DC.
if you have ~12v @ 3K, prolly reg/rec.

rotors are pretty indestructable, less so stators

check to see if stator wire was pinched/shorted between cases.
if wires are good, then there is short in stator and it will need to be replaced.

test:
VOM neg to ground, VOM pos to each white wire for continuity - there should be none. (continuity indicates short)

if you are uncertain about procedure - check the KB, there is a post of step-by-step on stator replacement in it.

#3:   Author: keratos Post Posted: Fri Jun 11, 2010 3:21 am

mark75 wrote (View Post): have you checked the regulator/rectifier?
put VOM on the battery, @ about 3000rpm should be about 14.4 volts DC.
if you have ~12v @ 3K, prolly reg/rec.

I said in my original post...
"...the charging volts with the engine running. Was 12.5V"

mark75 wrote (View Post): check to see if stator wire was pinched/shorted between cases. if wires are good, then there is short in stator and it will need to be replaced.
test:
VOM neg to ground, VOM pos to each white wire for continuity - there should be none. (continuity indicates short)


I said in my original post...
"With a multimeter, I tested each of the pairs of three wires for resistance. The resistance in each case was around 1.2ohms. The specification is 0.5ohms +/- 10%..... I also get continuity from any of the white connectors coming out of the alternator assy , to ground/earth. "

Is this any help to anyone?
Is is the rectifier, the stator or the rotor?

Thanks

#4:   Author: mark75 Post Posted: Fri Jun 11, 2010 5:35 am

No thanks required, & I don't need your attitude I have plenty of my own.

did you check for pinched wires? you didn't say.

you said "engine running".
that covers a big field - 01rpm to 7000rpm?
at idle (~950-1050 rpm) you only will get ~12v even with a perfectly good system.

I also said if the wires are good the stator needs to be replaced.

I also said that rotors are pretty indestructable (barring lightening or artillery strike).
basically being just rotating magnets, they rarely sprout defects on their own.

A defective stator will eventually burn-out a reg/rec.
If the PO was repeatedly having to re-charge the battery to get home, suspect the reg/rec is toast, too.

Is this any help to you?

You're welcome.

#5:   Author: keratos Post Posted: Fri Jun 11, 2010 5:44 am

Wow. Touchy. I'd heard the southern states were welcoming, warm, understanding and certainly not sarcastic.

THANKS! There, feel better now.

Dont read too much into my posts; no offence intended; just clarifying my original post; being a dumb limey maybe I need to tailor my ettiquette to USA standards.

So, if we may, can we please return to the problem at hand for which your worldy wisdom IS appreciated and very much respected.

The RPM was idle and upto around 3,000. Measured just around 12V charging.

The wires read 1.5 ohms between the pairs. I noted searching google that the correct value is around 0.5 ohm; but then last night I found someone who was saying 2ohms??

And, there is continuity between any of the three white wires and ground/earth/frame.

Havent tested the regulator/rectifier. Not sure how to do this?

Stator or rectifier/regulator?

What d'ya think Sir?

#6:   Author: mark75 Post Posted: Fri Jun 11, 2010 6:17 am

my apologies. I am squeezing this in while at work, and it's been a bad night.

sounds like you are going through the same thing I did with my '84-700.

sounds like the stator is dead and may have taken the r/r with it.

there is a test for the r/r involving testing continuity between the red wire and each white, and ground and than reversing the +/- probe, then repeating pattern.
actual reading is not so important as getting exact opposite when polarity changed. (continuity vs infinity)
oh I'm getting a migraine.

I have to admit, electricity is magic to me.
(electrical things work until the magic smoke escapes) Laughing

please let me recommend doing a KB search for a manual, there are downloadable ones there. manual can come in pretty handy.

#7:   Author: keratos Post Posted: Fri Jun 11, 2010 6:43 am

Golly, I forgot the time difference. Its only 11:45am on this side of the pond.

Okay, will undertake these tests tonight and report back.

KB = Knowledge Base ??

Many thanks and good luck with the migrane.

D.

#8:   Author: grazingazer Post Posted: Fri Jun 11, 2010 9:54 am

yes kb = knowledge base

#9:  Re: Help with resolving charging system issue. Author: Delmeister Post Posted: Sat Jun 12, 2010 6:50 am

If you have continuity between any of the stator leads and ground, you will have reduced output, and you will stress some of the diodes in the RR. The exact effect will depend on the nature of the short and how the stator is wound (Y or Delta). Any schematics I have seen that represent the alternator internals show a Y connection. In a Y connection, one end of each of the three coils is connected to each other internally, and what you see coming out of the stator are the three other ends. When you measure the resistance between any two terminals, you measure two of the coils in series, so if you measured 1.2 ohms, each coil would have a resistance of 0.6 ohms.

Consider a situation where the one of the wires coming out of the alternator is pinched and perfectly shorted to ground. If you measured the resistance between that wire and ground it would be zero. The resistance between the other two leads and ground would be 1.2 ohms. For the case where the Y junction of the three coils is perfectly grounded, the resistance of each lead to ground would be 0.6 ohms. If the short is inside one of the coils, you will have some intermediate situation. Also all coils would pass a very high current at some point in the cycle. For the case of the shorted lead, full output would only be possible 1/3 of the time, and two of the six diodes in the RR would be passing a very high shorting current.

Bottom line is stator must not be shorted to ground. If it is, it may or may not take out the RR depending on how long the situation persists. Make sure the continuity you measure is actually due to an internal short rather than from a lead touching ground. If the RR fails in such a way that the internal diodes short out (rather than open up), then just replacing the stator could result in damage to it (the new stator) as well.

#10:   Author: 1986 XV700 Post Posted: Sat Jun 12, 2010 1:18 pm

Touch the two meter leads together and see what the meter reads. Subtract that number from what the meter reads while connected to the stator wires. That will give the actual resistance of the stator windings.

Because you stated that you read 1.2 ohms during all three tests, IMHO you don't have any pinched wires because your readings are higher than specs. It indicates to me that your meter might have a higher than normal resistance leads, perhaps .6 ohms or higher.

Check and clean the connectors from the stator to the R/R, and the R/R to the battery. There is also the chance of the battery being bad.

#11:   Author: keratos Post Posted: Sat Jun 12, 2010 1:43 pm

thanks guys for you infinitely more than me knowledge

Scott:
if no pinch or short, then why do all terminals of the stator connector, read continuity to earth

I cant see any wiring problem behind the alternator cover so why the short? Just wondering

Dnt understand

#12:   Author: pofarm Post Posted: Sat Jun 12, 2010 9:30 pm

Since you say you have continuity from any wire to ground (earth), I would say your stator is bad. You shouldn't have any continuity at all. Actually, 50 isn't bad for a new stator.

#13:  Re: Help with resolving charging system issue. Author: eaglebeak Post Posted: Sat Jun 12, 2010 11:02 pm

I agree that you've got either a stator problem or possibly one of the three white wires going to it has gotten pinched by a PO when putting the engine side cover back on - a common error.

Generally, even a bad stator doesn't short to ground except in some worse case scenario where one of the three coils has burned open and heat has caused it to touch ground someplace. Pulling the side cover to inspect the stator and wiring will be the first step.

#14:   Author: keratos Post Posted: Sun Jun 13, 2010 3:04 am

Ok. So it would appear the stator is defective. 50 is the cost for a 2nd hand one from breakers yard

Scott: The two leads of my digital multimeter read 0.0ohms when touched together.

Thanks guys. I will order and fit stator and report back.

Delmeister:Many thanks for your kind and detailed insightful knowledge which was most helpful.

#15:  Re: Help with resolving charging system issue. Author: Delmeister Post Posted: Sun Jun 13, 2010 4:39 am

You're Welcome.
It would be informative to know what your actual measured resistances to ground are for the three leads --- fractions of an ohm? thousands of ohms?

@1986 XV700 -- The resistance measurement between stator leads will not be affected by a short to ground. However, there will be different effects from each individual lead to ground. In order to see this effect, the short must be of very low resistance, say fractions of an ohm. A short to ground of several thousand ohms will completely mask any lead-to-ground differences.

#16:  Re: Help with resolving charging system issue. Author: keratos Post Posted: Sun Jun 13, 2010 4:50 am

Delmeister wrote (View Post): You're Welcome.
It would be informative to know what your actual measured resistances to ground are for the three leads --- fractions of an ohm? thousands of ohms?

@1986 XV700 -- The resistance measurement between stator leads will not be affected by a short to ground. However, there will be different effects from each individual lead to ground. In order to see this effect, the short must be of very low resistance, say fractions of an ohm. A short to ground of several thousand ohms will completely mask any lead-to-ground differences.


Yes , of course , my apologies.

The resistance to ground was not tested; I used a digital multimeter with the setting for continuity (the diode icon). One probe on the chassis, another at each of the white terminals coming off the alternator assy. Continuity present on all three.

As I said, I did take off the cover and inspected the wiring into the assy but all looks fine, quite clean actually. No obvious shorts to the casing or whatever.

Very strange.

I will measure the resistance Ohms today, rather than continuity, and report back to provide the requested data.

#17:   Author: grazingazer Post Posted: Sun Jun 13, 2010 1:42 pm

you should read infinity or your equivalent on the meter when testing from white wire to ground...any reading other than that means you have a short[s] from your stator windings to ground

#18:   Author: keratos Post Posted: Sun Jun 13, 2010 4:04 pm

used an analogue meter.
resistance across probes (touched) was 12ohms
resistance from any white wire on the alternator connector, to chassis or -ve battery terminal was also 12ohms
evidence then that there is "perfect" short

not sure how this is happening because the wires and connections are in good order. but there must be a short to ground somewhere in the stator housing. is this possible? i'm minded to buy a new stator but worried that it could be something else like the R/R. just looking for a final second opinion dear forum-ees, if possible. shall I plumb for a new stator? is there any other checks I can do?

#19:   Author: 1986 XV700 Post Posted: Sun Jun 13, 2010 7:46 pm

I overlooked his EDIT in the first post, should have paid more attention. I concur with the majority.

#20:   Author: grazingazer Post Posted: Mon Jun 14, 2010 8:39 am

if you are sure that the wires are not pinched and you tested them after unplugging the connector and performed the test on the stator side of the connection then the stator is defective...in addition it is not uncommon that the regulator may also be defective...you should test it too

#21:  (SOLVED) Help with resolving charging system issue. Author: keratos Post Posted: Tue Jun 15, 2010 5:46 am

I cannot remove the LEFT side cover to get the stator out.
HELP!
I've taken out all the bolts, removed the clutch cable, lowered the left hand side lower brace, but the cover still wont come off. There is hell of a resistance around the area I have circled in the pic. I seem to have taken more off than the clymer manual proposes.
any ideas guys?
I'm really pulling but it seems something is going to brake/snap.



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Last edited by keratos on Tue Jul 06, 2010 3:52 pm; edited 1 time in total

#22:   Author: pofarm Post Posted: Tue Jun 15, 2010 8:42 am

You have to remove the spool with the Torx head, the lever, and solenoid. The lever is held in with a shoulder bolt that runs vertically through it from the bottom. Make note of the way the lever and spring attach to the solenoid. Use threadlock on the shoulder bolt threads when you reinstall it.

#23:   Author: mark75 Post Posted: Tue Jun 15, 2010 9:16 am


remove the bolt that acts as a fulcrum, then the thing you have circled

note: observe this area closely inside when you remove the side case, there is a thinnish spring that will need special attention when re-assembling

due to the magnetic nature of the rotor & stator expect to feel some resistance-possibly like something may still be attached, but there are no "inside" fasteners.

the thing circled in yellow is part of your clutch adjustment. note the 3 balls & detents under it.
make sure they are positioned in the detents when you re-assemble or your clutch will be wonky and wont adjust right.



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#24:   Author: keratos Post Posted: Tue Jun 15, 2010 10:40 am

sh!t!
Attempts to undo the torx have rounded it off. Theres no way the torx screw can get a grip now.

Also the shoulder bolt is stuck fast. Just snapped an allen key and cant get it to budge. I do hope counter clockwise is the correct way. Thats what Ive been using to undo these - or not.

I bet Ive had it now ??

#25:   Author: mark75 Post Posted: Tue Jun 15, 2010 10:54 am

yep-cc is correct. PO may have gone over-board with Loc-Tite or epoxy even? doh

any chance of borrowing an impact driver for the allen head?

the torx head thing is problematic.
may have to totally bugger it and replace it. vice-grips maybe?

Good Hunting.

#26:   Author: keratos Post Posted: Tue Jun 15, 2010 1:34 pm

I've given up
Impact driver innefectual.
Took it to a local Yamaha dealer and workshop
Let them have a look. Cant get the crews out and dont want to make things worse than they are.
Thanks for all your help anyway
Do you want me to mark (SOLVED)?

#27:   Author: keratos Post Posted: Tue Jun 15, 2010 4:26 pm

mark75:
I know your spot on with the guide on what needs to be removed, but a question if I may:
How come the haynes manual and clymer manual - i have both - for the XV535/700/750/1100 mentions nothing about removing that bit with a torx screw nor the shoulder bolt??

#28:   Author: mark75 Post Posted: Wed Jun 16, 2010 4:52 am

confused dunno.
over sight on their part, I reckon.

#29:   Author: keratos Post Posted: Wed Jun 16, 2010 5:32 am

yup. guess so.
well, I well and truly screwed up with the torx. it cammed-out to a more-or-less circle.
the local shop will have to deal with it.
I dont know what to do now.
cheers anyway

#30:   Author: Delmeister Post Posted: Wed Jun 16, 2010 6:05 am

keratos wrote (View Post): I've given up
Impact driver innefectual.
Took it to a local Yamaha dealer and workshop
Let them have a look. Cant get the crews out and dont want to make things worse than they are.
Thanks for all your help anyway
Do you want me to mark (SOLVED)?

Don't mark this solved. How did the shop guys react to the situation?

#31:   Author: keratos Post Posted: Wed Jun 16, 2010 6:52 am

They have not "reacted" yet.

I put it all back together, rode it to the shop and left it with them just saying "the charging system aint working"

No point leaving it as it was in the hope of reduced repair fees, because in this country you get ripped off whatever. Its common knowledge and everyone including me experiences it. They would find some excuse to charge the same as a full stripdown, repair, and reinstall. If you strip down the vehcile to make it easy for them ,they just add a margin on the spares profit. And if you give them the spares they often wont repair it for you.

This is the same for most shops beit car or bike, private or dealer.

We'll wait and see.

I just wish I had not cammed out the torx with a stupid cheap torx bit and handle. Should have used high quality bit and impact driver. Ah well.

#32:   Author: keratos Post Posted: Tue Jul 06, 2010 3:51 pm

Bike back now
150 to fix
darn!
It was the stator. New stator was 90. 60 labour.
Marking (SOLVED)
ViragoTechForum.com XV750 (SOLVED) Help with resolving charging system issue.


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