Author Topic: testing the stator am i doing it right? (Read 24990 times)

j4hfr34k · « **on:** March 15, 2012, 05:46:51 PM »

got a question i followed the steps here
http://www.ehow.com/how_7845606_test-honda-cb750-motorcycle-stator.html
and on step three, i have 7 wires instead of five, i have the 3 yellow, 2 red and 2 green, when i checked for coninuity, i got nothing on any of the yellow wires to any of the other wires, am i not doing something right, or do i just have a really blown stator?

i just bought the multimeter at sears a cpl days ago and had it on the continuity setting according to the manual. its a craftsman pocket multimeter 82351

Spanner 1 · « **Reply #1 on:** March 15, 2012, 07:00:25 PM »

Hi Cody..... the yellow wires ( from the stator coil ) should read 0.2 ohms from any one yellow to any other yellow. The reds and greens on the 750A wiring are just 'doubled-up'... so use either red and green.
Need to unplug the 8-way plug behind the airbox to test the stator. Set your dig. meter to the lowest ohms scale and read from yel. to yel. in all combinations. Should be 0.2 ohms. Then unplug the rectifier and do the tests on it with your meter on the' diode' setting.... usually all the way clicked to the left, before off. Some meters beep on this setting which makes it easier . Beep one way and no beep with red/black leads reversed...... hope this helps

j4hfr34k · « **Reply #2 on:** March 15, 2012, 10:55:59 PM »

thanks that helps a lot ill ne checking it in the morning.

singedebile · « **Reply #3 on:** March 15, 2012, 11:56:37 PM »

hmmmm, (not to hijack the thread) I have been having some charging issues right now on my 550 and I was reading 1.2-1.1 on all three yellow wires in every combination (had the voltmeter set to the lowest setting), does this mean my stator is bad (or are these values fine for a 550)? I thought they very rarely ever went bad... I hate the idea of buying a questionable used one off ebay.

bryanj · « **Reply #4 on:** March 16, 2012, 03:22:26 AM »

You dont use the volt setting to check, i hope you ment ohms and you really need to check the resistance probe to probe (never zero) first and deduct that from your readings.

Also only ever seen one bad 500/550 stator and that was mechanical damage (rubbed winding leading to broken wire) which was easily repaired, come to think of it it was on the bike in the avatar!!

trueblue · « **Reply #5 on:** March 16, 2012, 03:56:43 AM »

Don're forget to see what the internal resistance of the meter is before doing any readings just touch the 2 probes together and note the reading then subtract this figure grim any future readings. For instance if the meter reads 0.4 ohms then you do a test of the stator anOood it reads 0.9 ohms the actual resistance of the stator is 0.5 ohms

j4hfr34k · « **Reply #6 on:** March 16, 2012, 07:44:08 AM »

according to those tests my rectifier tesetd good on the diode reading nearly the same both directions with no errors or 0l, my stator is bad i think, two of the yellow wires did good around 2.1 after subtracting th internal resistance, but the third went ol one way, and all kinds of crazy readings the other way, how do you test the regulator? i just replaced the regulator and rectifier last spring and the charging system worked again for a cppl months then stopped, i have a feeling it is probably sstill good, but want to test it to be sure.

thrutheframe · « **Reply #7 on:** March 16, 2012, 08:27:29 AM »

If im not mistaaken all the bikes you list as owning have a charging system more like my 79 CB650 than earlier 750's. That being said, I'd be checking the rotor. Thats the more likely piece to go bad and when it does it takes the rec/reg combo with it. Remove the alternator cover and clean the rings with a bit of fine sandpaper. Meter between the rings on the ohms scale, reading should be in the 4-10 ohms range.

j4hfr34k · « **Reply #8 on:** March 16, 2012, 09:37:03 AM »

thanks for the heads up and how to check the rotor. am i right in thinking the stator went bad according to the readings i got?

Spanner 1 · « **Reply #9 on:** March 16, 2012, 10:49:10 AM »

Let's make sure were on the same page

.... to test the stator coil your meter needs to be 'clicked' to the lowest 'Ohms' setting , not the diode setting. The 8-way plug needs to be disconnected and a good clean connection io each yellow is essential as your are reading a very low resistance.... as suggested above , go ahead and touch the red and black meter probes together first ( must be on lowest Ohms scale already ) and note the reading.... then read between yel. to yel. to yel. Substract the reading you got with the probes together = actual stator reading..... then 'click' to diode setting on your meter to do the rectifier test ...you could go ahead and test the field coil too while your meter is on it's lowest Ohms scale. Put your probes on the White and Green wire in the 8-way connector ( always disconnected, always the half that has the wires that go into the engine case btw for stator and field test )
Field coil = 7.2 Ohms if good.... ( did you substract the probe-to-probe resistance? )
Stator, any y. to y. = 0.2 Ohms if good.....
Good luck.

j4hfr34k · « **Reply #10 on:** March 16, 2012, 11:06:24 AM »

yes i did the test o the lowest ohm setyting, mine is automatic for ohms, 2 of the 3 yellows were good, but the third one showed OL and a bunch of random jumping reasings when probes were switched around, and then switched to the diode setting after looking up which on it was in the manual to be sure and the rectifier tested good both ways, mine has two seperate plugs the 5 (7 since the green and red are doubled)wires going to the regulator on one plug , thats what i tested the yellow to yellows from on the end going to the engine. to test the field coil do i check the wires coming off of the rectifier?

j4hfr34k · « **Reply #11 on:** March 16, 2012, 11:10:28 AM »

the second isnt really a plug as the wires each pug into the rectifier individually.

Spanner 1 · « **Reply #12 on:** March 16, 2012, 11:21:00 AM »

Field coil test is probes to the White and Green ( that go into the motor )... not from the reg/rect

singedebile · « **Reply #13 on:** March 16, 2012, 11:23:16 AM »

thanks for the help, I'll double check I was doing it right (but the bike is at my friends shop right now). There are some wierd charging issues with my bike right now.. I know the rectifier is good, and I am putting in a new better ground connection into the harness tonight. I'll get back with the readings tonight.

j4hfr34k · « **Reply #14 on:** March 16, 2012, 11:27:57 AM »

i just did the tests again, and the stator is bad, one of the yellow wires is getting no reading at all, the fieeld coil seems to test god after subtracting the difference from touching the probes straight to each other, i also tested my old recitifer and it also tested good, how do i test the regulator to see if perhaps the stator was the problem in the first place?

j4hfr34k · « **Reply #15 on:** March 16, 2012, 12:51:48 PM »

i foouund out how to test the regulator and it looks like the old one was fried, the new one i swapped out tests good, so it looks like i just need to find a good stator,

j4hfr34k · « **Reply #16 on:** March 16, 2012, 07:15:25 PM »

i think i found a stator waiting to hear back from them to make sure they have it in stock

bryanj · « **Reply #17 on:** March 17, 2012, 01:52:34 AM »

Before you spend money check again with the stator removed and at the point the yellows join the windings, problems are usually in the yellow wires and/or spade connectors not the windings

j4hfr34k · « **Reply #18 on:** March 28, 2012, 09:45:29 AM »

i got the cover off, but i have a few questions as to testing it,
first i had saw a post on here where someone had found out it was a frayed wire or unhooked connecter behind the shifter cover, so i reomved the shifter cover only to find out that i dont have any wires running behind it, but since i had drained the oil i went ahead and removed the stator cover too, so my second queston is this
to replace the stator or check the connections where do i look mine has the wires coming out of the engine case by the starter cover, and going to the reg and rec,
my understanding is there is another connector in between that goes to the stator that may be unhooked or wore out, and to replace the stator id need to find that connector to hook the new one into.

lucky · « **Reply #19 on:** March 28, 2012, 10:54:31 AM »

Quote from: j4hfr34k on March 15, 2012, 05:46:51 PM

got a question i followed the steps here
http://www.ehow.com/how_7845606_test-honda-cb750-motorcycle-stator.html
and on step three, i have 7 wires instead of five, i have the 3 yellow, 2 red and 2 green, when i checked for coninuity, i got nothing on any of the yellow wires to any of the other wires, am i not doing something right, or do i just have a really blown stator?

i just bought the multimeter at sears a cpl days ago and had it on the continuity setting according to the manual. its a craftsman pocket multimeter 82351

You have to have the meter set on the 200 ohms scale. Thats the trick.

Watch these two good videos.
1. PART 1 of 3: Theory & Testing of Honda CB750 900 DOHC Motorcycle Charging System @ rcycle.com

2. PART 2 of 3: Theory & Testing of Honda CB750 900 DOHC Motorcycle Charging Systems @ rcycle.com

Spanner 1 · « **Reply #20 on:** March 28, 2012, 12:02:45 PM »

Cody, there are 3 bullet and socket connectors close to the stator ( under the alt. cover ) they will be covered in oil ( normal ) and need to be undone and examined for poor connection.... several posts about a poor connection here causing no charging . Go ahead and test the stator again from these ( shone-up ) connectors... hope it's here and not the in the windings

j4hfr34k · « **Reply #21 on:** March 29, 2012, 01:57:07 PM »

Quote from: Spanner 1 on March 28, 2012, 12:02:45 PM

Cody, there are 3 bullet and socket connectors close to the stator ( under the alt. cover ) they will be covered in oil ( normal ) and need to be undone and examined for poor connection.... several posts about a poor connection here causing no charging . Go ahead and test the stator again from these ( shone-up ) connectors... hope it's here and not the in the windings

quick question i got it off, but when i was trying to pull on the wires to find where the connectores were they came unplugged from inside the engine somewhere so I'm not sure where the other ends are ill have to find them,

i have three female bullet type connectors and two male type bullet connectors i believe the three female ones are the yellow wires ii haven't got all the oil off yet tho to be sure,

to test It from here, what to i put the other end of the meeter on to test the yellow wires, i had one yellow wire test bad when testing at the big plug to thee regulator etc

nayto550 · « **Reply #22 on:** March 29, 2012, 02:25:19 PM »

Here's a diagram of a 3-phase stator, you need to measure resistance across all three coils. We can call the three yellow wires A, B and C, and you'll end up with 3 resistance measurements: A to B, A to C and B to C. I don't know what the spec is for the impedence off the top of my head, but that was brought up earlier in the thread.

TwoTired · « **Reply #23 on:** March 29, 2012, 02:52:21 PM »

I think you'll find our SOHC4 stators are star wired rather than Delta. They are tested the same way, though.

j4hfr34k · « **Reply #24 on:** March 29, 2012, 03:15:05 PM »

i tested it and it tests good across alll three so im assuming it must have been one of the wires/ connectors going up, and considering i lost the plugs when i took it of its highly likely at least one was loose or unplugged already.

scottly · « **Reply #25 on:** March 29, 2012, 06:49:46 PM »

Quote from: TwoTired on March 29, 2012, 02:52:21 PM

I think you'll find our SOHC4 stators are star wired rather than Delta. They are tested the same way, though.

"star wired"?? I always thought that was a "Y", or "WYE" configuration. I learn something new everyday.....

TwoTired · « **Reply #26 on:** March 29, 2012, 07:23:12 PM »

Quote from: scottly on March 29, 2012, 06:49:46 PM

Quote from: TwoTired on March 29, 2012, 02:52:21 PM
I think you'll find our SOHC4 stators are star wired rather than Delta. They are tested the same way, though.
"star wired"?? I always thought that was a "Y", or "WYE" configuration. I learn something new everyday.....

More sarcasm?

I'm more familiar with wye, or Y also. But, star wiring is also correct. And further, it applies to alternators wired in the same physical configuration but have more than 3 poles/phases. In fact, alternators can be wired with any number of phases besides 3. It isn't very common though.

Anyway, for your edification...
http://www.reuk.co.uk/Star-Delta-Wiring-for-Alternators.htm

Would you call the alternator below "Y" or "star" wired?

scottly · « **Reply #27 on:** March 29, 2012, 07:43:18 PM »

Quote from: TwoTired on March 29, 2012, 07:23:12 PM

Would you call the alternator below "Y" or "star" wired?

According to the label, it is a generator, not an alternator. The schematic leads me to believe that it may have brushes, as there are no connections shown between the inner ends of any of the coils. What does this have to do with an SOHC alternator?

TwoTired · « **Reply #28 on:** March 29, 2012, 11:01:19 PM »

The inner connections are all common. It's obvious to those who aren't deliberately obtuse.

generator
1. A machine that converts mechanical energy into electricity to serve as a power source for other machines. Electrical generators found in power plants use water turbines, combustion engines, windmills, or other sources of mechanical energy to spin wire coils in strong magnetic fields, inducing an electric potential in the coils.

As it puts out AC, it is more precise to call it an alternator, but it is also a generator.

bryanj · « **Reply #29 on:** March 29, 2012, 11:05:10 PM »

Personaly i would call it two seperate 3 phase generators using a common field rotor in one casing

Spanner 1 · « **Reply #30 on:** March 29, 2012, 11:23:27 PM »

Cody... maybe that's your problem ( been posted before ) about poor/broken connection under the alt. cover. Test the 3 yellow wires to the stator there to confirm it's good or bad.... make sure the 3 connectors are good and clean first ....

TwoTired · « **Reply #31 on:** March 29, 2012, 11:35:04 PM »

Quote from: bryanj on March 29, 2012, 11:05:10 PM

Personaly i would call it two seperate 3 phase generators using a common field rotor in one casing

No. It really is a six phase alternator. It can drive two, three phase loads independently, or it can drive a 6 phase to 3 phase transformer for the purpose of using commonly available equipment that doesn't require DC conversion. It was intended for a Wind or Hydro power application.
It was/is experimental, and I don't know if any were actually built. It was only offered to show that "star" has less limitations than "Y" as a descriptor and is still accurate.

Cheers,

trueblue · « **Reply #32 on:** March 30, 2012, 02:52:26 AM »

Quote from: scottly on March 29, 2012, 06:49:46 PM

Quote from: TwoTired on March 29, 2012, 02:52:21 PM
I think you'll find our SOHC4 stators are star wired rather than Delta. They are tested the same way, though.
"star wired"?? I always thought that was a "Y", or "WYE" configuration. I learn something new everyday.....

When I was doing my apprenticeship I was taught that they were star wound and delta wound, to be honest I've never heard of a 'Y' wound alternator.

j4hfr34k · « **Reply #33 on:** March 30, 2012, 06:55:45 AM »

Quote from: Spanner 1 on March 29, 2012, 11:23:27 PM

Cody... maybe that's your problem ( been posted before ) about poor/broken connection under the alt. cover. Test the 3 yellow wires to the stator there to confirm it's good or bad.... make sure the 3 connectors are good and clean first ....

i was nable to test the stator through the connections under the alternator and it did test ggood, o now i have to find the connectors t unplugged from so i can clean and check them and hoprfully well be bback on the road this weekend.

j4hfr34k · « **Reply #34 on:** April 23, 2012, 10:42:32 AM »

Quote from: Spanner 1 on March 15, 2012, 07:00:25 PM

Hi Cody..... the yellow wires ( from the stator coil ) should read 0.2 ohms from any one yellow to any other yellow. The reds and greens on the 750A wiring are just 'doubled-up'... so use either red and green.
Need to unplug the 8-way plug behind the airbox to test the stator. Set your dig. meter to the lowest ohms scale and read from yel. to yel. in all combinations. Should be 0.2 ohms. Then unplug the rectifier and do the tests on it with your meter on the' diode' setting.... usually all the way clicked to the left, before off. Some meters beep on this setting which makes it easier . Beep one way and no beep with red/black leads reversed...... hope this helps

are the red and green wires on that plug the same as the white and green wires you said to test the field coil?

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Author Topic: testing the stator am i doing it right? (Read 24990 times)