Have you tested the various parts of an alternator? - Page 3

macafee2 · 22nd March 2023, 06:09

Quote:

Originally Posted by 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. ...

I have added a link to your thread. Hope it is of use, there is also a Denso web site in the USA.

macafee2

xsport · 22nd March 2023, 11:22

keep up the good work macafee2 !! its a pity that your doing a diesel model alternator. i could have gleaned alot of knowledge for the testing side of things as im sure your ohms resistances will be different to the petrol as your amps output is much higher than the petrol models. if i can get my parts i will be following in your footsteps for refurbishing mine. !! its an interesting thread to follow ... and you will enjoy it .. i think !!! ...

macafee2 · 22nd March 2023, 13:23

Quote:

Originally Posted by xsport

keep up the good work macafee2 !! its a pity that your doing a diesel model alternator. i could have gleaned alot of knowledge for the testing side of things as im sure your ohms resistances will be different to the petrol as your amps output is much higher than the petrol models. if i can get my parts i will be following in your footsteps for refurbishing mine. !! its an interesting thread to follow ... and you will enjoy it .. i think !!! ...

Thanks. Watch this space as I am going to add some links to videos that I have watched, really good videos. No video is 100% unless it is for your item so I've been a bit lost with one but hoping I was on the right track.

macafee2

macafee2 · 22nd March 2023, 15:20

Testing the 3 wires of the windings, meter set to 2 meg I got 0 ohms
Testing Slip Rings, not confident, meter set to 200 k range I got 173.8. The stator was still in the windings.

Testing to the bottom 3 pins of the rectifier, red lead to alternator casing black lead to pins, I got 6.14, 6.10 and 6.11
Testing to the battery post and top pins black lead to post, red lead to pins I got 6.12, 6.08 and 6.10.

Videos worth watching
https://www.youtube.com/watch?v=aVvPzwtxdrM&t=4s
https://www.youtube.com/watch?v=f56-26I6idc&t=130s
https://www.youtube.com/watch?v=sTTfemu_gcY
https://www.youtube.com/watch?v=tT1kR1lpN1A Thanks to Synchromesh

macafee2

Synchromesh · 22nd March 2023, 18:17

[QUOTE=macafee2;2964347]Testing the 3 wires of the windings, meter set to 2 meg I got 0 ohms
Testing Slip Rings, not confident, meter set to 200 k range I got 173.8. The stator was still in the windings.

Testing to the bottom 3 pins of the rectifier, red lead to alternator casing black lead to pins, I got 6.14, 6.10 and 6.11
Testing to the battery post and top pins black lead to post, red lead to pins I got 6.12, 6.08 and 6.10.

The rotor and stator windings are thick copper wire with a low resistance so Mohm and kohm meter ranges are too high to test these. You need to use the ohm range on your meter. The meter selection dial will probably have resistance options suffixed with M and k. You don't want these. You want a range with no suffix that means it is just ohms. My meter has the option 200 which means on that range it can measure from a minimum of 0 ohms up to a maximum of 199.9 ohms. If I short the test leads together the display shows 00.2 which means the test leads are 0.2ohms. This could be subtracted from a stator measurement if you wanted to be precise. You can't decisively test diodes with a digital meter on the resistance range. You need to use the semiconductor range. This will be a diode symbol. The semiconductor range doesn't display the resistance of the diode because that varies according to the voltage that is biasing it. The semiconductor range displays the voltage required to forward bias the diode or in other words the voltage required to make it fully conduct a current. When the meter is connected such that it forward biases the diode (makes it conduct) it will display 600 to 750 which represents 0.6V to 0.75V. When the meter is connected such that it reverse biases the diode (doesn't make it conduct) it should display 1 indicating that the diode is not conducting. If the meter displays 000 when connected both ways the diode is short circuit so will not work.

macafee2 · 22nd March 2023, 18:30

[QUOTE=Synchromesh;2964370]

Quote:

Originally Posted by macafee2

Testing the 3 wires of the windings, meter set to 2 meg I got 0 ohms
Testing Slip Rings, not confident, meter set to 200 k range I got 173.8. The stator was still in the windings.

Testing to the bottom 3 pins of the rectifier, red lead to alternator casing black lead to pins, I got 6.14, 6.10 and 6.11
Testing to the battery post and top pins black lead to post, red lead to pins I got 6.12, 6.08 and 6.10.

The rotor and stator windings are thick copper wire with a low resistance so Mohm and kohm meter ranges are too high to test these. You need to use the ohm range on your meter. The meter selection dial will probably have resistance options suffixed with M and k. You don't want these. You want a range with no suffix that means it is just ohms. My meter has the option 200 which means on that range it can measure from a minimum of 0 ohms up to a maximum of 199.9 ohms. If I short the test leads together the display shows 00.2 which means the test leads are 0.2ohms. This could be subtracted from a stator measurement if you wanted to be precise. You can't decisively test diodes with a digital meter on the resistance range. You need to use the semiconductor range. This will be a diode symbol. The semiconductor range doesn't display the resistance of the diode because that varies according to the voltage that is biasing it. The semiconductor range displays the voltage required to forward bias the diode or in other words the voltage required to make it fully conduct a current. When the meter is connected such that it forward biases the diode (makes it conduct) it will display 600 to 750 which represents 0.6V to 0.75V. When the meter is connected such that it reverse biases the diode (doesn't make it conduct) it should display 1 indicating that the diode is not conducting. If the meter displays 000 when connected both ways the diode is short circuit so will not work.

thank you, yes used the diode mode for the test of the rectifier.
I'll retest the windings tomorrow and post.

macafee2

macafee2 · 23rd March 2023, 17:21

On to 200 ohm range, I got a 0.00 ohm reading

macafee2

Synchromesh · 23rd March 2023, 17:57

In the video I told you about, the meter displayed 0.2ohms when the probes were shorted together. This is similar to what I see on my meter when the probes are shorted on the 200ohm range. In the video the resistance displayed on the meter from one star point to any other star point was 0.4ohms. As I said previously the meter lead resistance can be subtracted to give the actual star to star resistance:

0.4ohms(meter reading)-0.2ohms(meter leads)=0.2ohms(true stator resistance)

If your meter displayed 0.0ohms from star point to star point on the stator windings there is something wrong with your meter. Do you have any low value resistors you could use to check your meter. Perhaps you have some resistors left over from repairing a Rover 75 cooling fan?

macafee2 · 23rd March 2023, 19:39

Quote:

Originally Posted by Synchromesh

In the video I told you about, the meter displayed 0.2ohms when the probes were shorted together. This is similar to what I see on my meter when the probes are shorted on the 200ohm range. In the video the resistance displayed on the meter from one star point to any other star point was 0.4ohms. As I said previously the meter lead resistance can be subtracted to give the actual star to star resistance:

0.4ohms(meter reading)-0.2ohms(meter leads)=0.2ohms(true stator resistance)

If your meter displayed 0.0ohms from star point to star point on the stator windings there is something wrong with your meter. Do you have any low value resistors you could use to check your meter. Perhaps you have some resistors left over from repairing a Rover 75 cooling fan?

ok my mistake for wording it the way I did, it showed 2 ohms for the leads and 2 ohms when testing so I worded it as showing 0 ohms.
I am not trying to give exact figures for anyone else's alternator but just somewhere to start.
I can not even suggest on any of these figures, at what value one should consider they have a problem.

I'm wondering if KWIL had the right idea in posts 2 and 4, poor contact with the slip ring where it was not shiny clean.
May be if I can get the old slip ring off without breaking the wires, I may splash out on a new slip ring.

macafee2

Synchromesh · 24th March 2023, 09:57

A few months ago a family member's Fiesta charge light started flickering then moved to permanently illuminated. I stripped the alternator expecting it would need new brushes. I found one brush had a bit of crud on it so it was sticking in the brush holder. The spring was not strong enough to press it onto the slip ring. Both brushes showed minimal wear. as did the slip rings. I cleaned off the crud and reassembled the alternator using the original brushes. It has worked perfectly since. I don't think you commented on the condition of your brushes.

22nd March 2023, 11:22	#22
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,741 Thanks: 358 Thanked 419 Times in 310 Posts	keep up the good work macafee2 !! its a pity that your doing a diesel model alternator. i could have gleaned alot of knowledge for the testing side of things as im sure your ohms resistances will be different to the petrol as your amps output is much higher than the petrol models. if i can get my parts i will be following in your footsteps for refurbishing mine. !! its an interesting thread to follow ... and you will enjoy it .. i think !!! ...

22nd March 2023, 15:20	#24
macafee2 This is my second home Rover 75 Saloon & Tourer Join Date: Sep 2012 Location: Lincoln Posts: 14,961 Thanks: 1,630 Thanked 3,032 Times in 2,181 Posts	Testing the 3 wires of the windings, meter set to 2 meg I got 0 ohms Testing Slip Rings, not confident, meter set to 200 k range I got 173.8. The stator was still in the windings. Testing to the bottom 3 pins of the rectifier, red lead to alternator casing black lead to pins, I got 6.14, 6.10 and 6.11 Testing to the battery post and top pins black lead to post, red lead to pins I got 6.12, 6.08 and 6.10. Videos worth watching https://www.youtube.com/watch?v=aVvPzwtxdrM&t=4s https://www.youtube.com/watch?v=f56-26I6idc&t=130s https://www.youtube.com/watch?v=sTTfemu_gcY https://www.youtube.com/watch?v=tT1kR1lpN1A Thanks to Synchromesh macafee2

22nd March 2023, 18:17	#25
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 626 Thanks: 50 Thanked 44 Times in 32 Posts	[QUOTE=macafee2;2964347]Testing the 3 wires of the windings, meter set to 2 meg I got 0 ohms Testing Slip Rings, not confident, meter set to 200 k range I got 173.8. The stator was still in the windings. Testing to the bottom 3 pins of the rectifier, red lead to alternator casing black lead to pins, I got 6.14, 6.10 and 6.11 Testing to the battery post and top pins black lead to post, red lead to pins I got 6.12, 6.08 and 6.10. The rotor and stator windings are thick copper wire with a low resistance so Mohm and kohm meter ranges are too high to test these. You need to use the ohm range on your meter. The meter selection dial will probably have resistance options suffixed with M and k. You don't want these. You want a range with no suffix that means it is just ohms. My meter has the option 200 which means on that range it can measure from a minimum of 0 ohms up to a maximum of 199.9 ohms. If I short the test leads together the display shows 00.2 which means the test leads are 0.2ohms. This could be subtracted from a stator measurement if you wanted to be precise. You can't decisively test diodes with a digital meter on the resistance range. You need to use the semiconductor range. This will be a diode symbol. The semiconductor range doesn't display the resistance of the diode because that varies according to the voltage that is biasing it. The semiconductor range displays the voltage required to forward bias the diode or in other words the voltage required to make it fully conduct a current. When the meter is connected such that it forward biases the diode (makes it conduct) it will display 600 to 750 which represents 0.6V to 0.75V. When the meter is connected such that it reverse biases the diode (doesn't make it conduct) it should display 1 indicating that the diode is not conducting. If the meter displays 000 when connected both ways the diode is short circuit so will not work.

23rd March 2023, 17:21	#27
macafee2 This is my second home Rover 75 Saloon & Tourer Join Date: Sep 2012 Location: Lincoln Posts: 14,961 Thanks: 1,630 Thanked 3,032 Times in 2,181 Posts	On to 200 ohm range, I got a 0.00 ohm reading macafee2

23rd March 2023, 17:57	#28
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 626 Thanks: 50 Thanked 44 Times in 32 Posts	In the video I told you about, the meter displayed 0.2ohms when the probes were shorted together. This is similar to what I see on my meter when the probes are shorted on the 200ohm range. In the video the resistance displayed on the meter from one star point to any other star point was 0.4ohms. As I said previously the meter lead resistance can be subtracted to give the actual star to star resistance: 0.4ohms(meter reading)-0.2ohms(meter leads)=0.2ohms(true stator resistance) If your meter displayed 0.0ohms from star point to star point on the stator windings there is something wrong with your meter. Do you have any low value resistors you could use to check your meter. Perhaps you have some resistors left over from repairing a Rover 75 cooling fan?

24th March 2023, 09:57	#30
Synchromesh Gets stuck in Rover 75 Saloon Join Date: Jan 2010 Location: Preston Posts: 626 Thanks: 50 Thanked 44 Times in 32 Posts	A few months ago a family member's Fiesta charge light started flickering then moved to permanently illuminated. I stripped the alternator expecting it would need new brushes. I found one brush had a bit of crud on it so it was sticking in the brush holder. The spring was not strong enough to press it onto the slip ring. Both brushes showed minimal wear. as did the slip rings. I cleaned off the crud and reassembled the alternator using the original brushes. It has worked perfectly since. I don't think you commented on the condition of your brushes.