Have you tested the various parts of an alternator?

[macafee2]

Originally Posted by DMGRS

If you do find you have any particular part that's worn, we have the slip rings, brushes etc here: https://www.dmgrs.co.uk/products/rov...-and-yle102500

When testing the resistance of the windings from the slip rings it should be stable - if it varies, you may well find the rings are worn through to the plastic core (as mine were at 170,000 miles).

thanks. I cannot see the plastic through the rings.
Valeo will not give me any test readings, I assume they are commercially sensitive so it is understandable.
Unless I know what test results I should be getting, I'm pretty much flogging a dead horse.
Blindly changing parts is a waste of money. If a draw a blank, perhaps I will strip it down and put it back together again just for experience.

macafee2

[KWIL]

May I suggest that you do not spin the armature whilst testing, you are measuring resistance by passing a small current from the test meter, spinning will probably generate some voltage output which would interfere with your measurment.


Try again with no movement?

[macafee2]

Originally Posted by KWIL

May I suggest that you do not spin the armature whilst testing, you are measuring resistance by passing a small current from the test meter, spinning will probably generate some voltage output which would interfere with your measurment.


Try again with no movement?

Thank you. I will leave it overnight to see if tomorrow it is any different. Could the alternator be holding anything similar to the way a capacitor does?
Electronics is not my thing.

macafee2

[KWIL]

Nothng like that I am afraid

[Synchromesh]

https://www.google.com/search?client...id:tT1kR1lpN1A


The above video is quite good. The rotor should be just a few ohms, it is 2.9 ohms in the video which is typical but it could be a bit higher. Your meter should be set to the lowest resistance range available. On a typical budget digital meter this would be 200 ohms. I wonder if you have a better quality meter that auto ranges. If you do you would just set the range selector to ohms and the meter would decide which range to use. If you do have an auto ranging meter and your fingers are touching the metal part of the probes that may explain why you are getting erratic measurements because the meter may be trying to measure the resistance of your body instead of the rotor winding.

You should also ensure that you get an open circuit measurement between the slip rings and the rest of the rotor (i.e. the bearing).

[macafee2]

Originally Posted by Synchromesh

https://www.google.com/search?client...id:tT1kR1lpN1A


The above video is quite good. The rotor should be just a few ohms, it is 2.9 ohms in the video which is typical but it could be a bit higher. Your meter should be set to the lowest resistance range available. On a typical budget digital meter this would be 200 ohms. I wonder if you have a better quality meter that auto ranges. If you do you would just set the range selector to ohms and the meter would decide which range to use. If you do have an auto ranging meter and your fingers are touching the metal part of the probes that may explain why you are getting erratic measurements because the meter may be trying to measure the resistance of your body instead of the rotor winding.

You should also ensure that you get an open circuit measurement between the slip rings and the rest of the rotor (i.e. the bearing).

Thanks I'll watch the video.

macafee2

[macafee2]

This morning testing the alternator again the resistance climbed when measuring across the slip rings.
Having watched the very useful video Synchromesh linked to I am going to strip the alternator down and go from there.
Appreciate the help given.

macafee2

[Synchromesh]

Have you got something that has a known resistance that you can use to check your meter? Perhaps your meter or the meter leads are faulty.

[macafee2]

Originally Posted by Synchromesh

Have you got something that has a known resistance that you can use to check your meter? Perhaps your meter or the meter leads are faulty.

Having tested, retested and tested again I took the test meter apart and found a blown fuse. Frustrating as I'd only just replaced one. I then got steady readings but will test again tomorrow and jot down the readings and post for anyone else.
The video you linked to was very helpful but I had to test and watch it a couple of times. I will, also link to some other videos that have been of help
From the tests I managed to do after changing the fuse I dont think I've found a fault.
If I can fix the alternator all well and good but taking it apart is good experience. I need to make up a "spanner" with 24mm cut down socket welded to some flat metal as I need to put a torx bolt remover through the middle if I want to remove the rotor. I will also need a bearing puller if I want to remove the slip ring.
I've spent a lot of time achieving very little today, the joy of being retired

macafee2

[xsport]

been following this thread and without a semi hijack , this is for the diesel alternators . i know that mat does the brush/regulators for these but what is there for the petrol models apart from a new/old stock version from mat ? can we get brushes and regulators still for these. they are denso YLE102330 alternators. anyone know where (apart from the USA ) ? there are plenty of us out here with these. sorry for the thread interupt. ...