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Help identifying rectifier
- Thread starter DevonDel
- Start date
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- Tags
- electrical
Disconnect both wires from the brushes. Use your ohmmeter to measure from each brush terminal to the alternator frame. That should be open circuit (high resistance). If you find it shorted to ground (low resistance), then perhaps its something like 2M suggests, or the rotor windings themselves could be shorted out to the rotor frame (time for a new rotor).
DevonDel
XS650 Member
Thanks for the reply....but I'm not sure what you mean by alternator frame? Do you mean the stator casing itself?
I tested between the bushes and the stator outer and there was no open circuit, as in the reading was closed.
Your brushes are the early type. The inside brush originally grounded through the three steel screws to the stator. It also had a black wire that ran up into the harness ground.
The way it is now the three nylon screws unground the brush from the stator. The nylon won't carry electricity to ground.
On your set up by the reg/rec is a plug connector, This lets you unplug the reg/rec. Unplug it.
Now on the harness side of the plug find the green wire. Use you multimeter set on a low ohm scale. Touch one probe to the green wire in the plug. Touch the other probe to the green wire at the brushes. You should get a low ohm reading. At or very near zero.
Now move the probe from the green wire to the body of the stator. This should give you a very high ohm reading, infinity would be ideal.
This indicates the green wire is connected to the brush and is not shorting to ground. This is good.
On the other brush touch one probe to the black wire at the brush and at the brown wire in the plug. This should get a low ohm reading. Move the probe from the black brush wire and touch the stator. An high ohm reading here as with the green wire is good.
This shows the black wire brush is connected to the brown wire. It also shows it's not shorting to ground.
If in either of these tests you find continuity, a low ohm reading, from the wires to the stator, you have a short to ground.
This will blow the fuse.
At the brushes with them removed use the lowest ohm scale on your meter. Touch the probes together, remember the reading you get. This is the ohms of the test leads.
Now touch one probe to each slip ring on the rotor. You can easily reach one ring through the opening in the stator. You need to reach through the brush mounting hole to reach the other. You might need to remove the brush holder to reach in better.
You should get a reading of about 5 ohms, +or- 10%.
When measuring low ohms You check the ohms then subtract the ohms of the leads from the test reading to get actual ohms.
As an example, one of my meters the leads test out to .7 ohms. If I use this to test a rotor and get a reading of say 6.3 ohms. I would then subtract the .7 from the 6.3 and get 5.6 as an actual ohms. This will be well with in the 10% tolerance.
Your numbers will be different.
Also check from the slip rings to the body of the stator. This should be infinity also.
On the brushes Are they both about 3/8 inch or longer? The wear limit is 1/4 inch but they often fail before they wear that far. I think this is because the tension of the spring gets so weak it can't push the brush against the sip ring firmly. Thus losing good contact.
With the reg/rec unplugged turn on the bike and check the voltage on the brown wire on the bike side of the of the connector. Should be at battery voltage.
Try these tests and report back what you find.
Leo
The way it is now the three nylon screws unground the brush from the stator. The nylon won't carry electricity to ground.
On your set up by the reg/rec is a plug connector, This lets you unplug the reg/rec. Unplug it.
Now on the harness side of the plug find the green wire. Use you multimeter set on a low ohm scale. Touch one probe to the green wire in the plug. Touch the other probe to the green wire at the brushes. You should get a low ohm reading. At or very near zero.
Now move the probe from the green wire to the body of the stator. This should give you a very high ohm reading, infinity would be ideal.
This indicates the green wire is connected to the brush and is not shorting to ground. This is good.
On the other brush touch one probe to the black wire at the brush and at the brown wire in the plug. This should get a low ohm reading. Move the probe from the black brush wire and touch the stator. An high ohm reading here as with the green wire is good.
This shows the black wire brush is connected to the brown wire. It also shows it's not shorting to ground.
If in either of these tests you find continuity, a low ohm reading, from the wires to the stator, you have a short to ground.
This will blow the fuse.
At the brushes with them removed use the lowest ohm scale on your meter. Touch the probes together, remember the reading you get. This is the ohms of the test leads.
Now touch one probe to each slip ring on the rotor. You can easily reach one ring through the opening in the stator. You need to reach through the brush mounting hole to reach the other. You might need to remove the brush holder to reach in better.
You should get a reading of about 5 ohms, +or- 10%.
When measuring low ohms You check the ohms then subtract the ohms of the leads from the test reading to get actual ohms.
As an example, one of my meters the leads test out to .7 ohms. If I use this to test a rotor and get a reading of say 6.3 ohms. I would then subtract the .7 from the 6.3 and get 5.6 as an actual ohms. This will be well with in the 10% tolerance.
Your numbers will be different.
Also check from the slip rings to the body of the stator. This should be infinity also.
On the brushes Are they both about 3/8 inch or longer? The wear limit is 1/4 inch but they often fail before they wear that far. I think this is because the tension of the spring gets so weak it can't push the brush against the sip ring firmly. Thus losing good contact.
With the reg/rec unplugged turn on the bike and check the voltage on the brown wire on the bike side of the of the connector. Should be at battery voltage.
Try these tests and report back what you find.
Leo
Yes, the stator casing is in fact the main part of the alternator.
Well that means the rotor windings are shorted out to the rotor body. The next step is to remove the rotor from the engine, and then use an ohmmeter to confirm that the slip rings are indeed shorted to the rotor body. Use the correct rotor removal tool.
DevonDel
XS650 Member
?..... I mean there is infinite resistance between the stator casing and the bushes....which is good right?
DevonDel
XS650 Member
Thank you thank you thank you Leo, here are my results.
Touch one probe to the green wire in the plug. Touch the other probe to the green wire at the brushes. You should get a low ohm reading. At or very near zero. = Check very near zero
Now move the probe from the green wire to the body of the stator. This should give you a very high ohm reading, infinity would be ideal. = Check reading infinity
On the other brush touch one probe to the black wire at the brush and at the brown wire in the plug. This should get a low ohm reading. = Check very low near zero
Move the probe from the black brush wire and touch the stator. An high ohm reading here as with the green wire is good. = Check reading infinity
Now touch one probe to each slip ring on the rotor. = Reads exactly 5ohms (with correction for lead resistance)
Both brushes are a very good length.
Touch one probe to the green wire in the plug. Touch the other probe to the green wire at the brushes. You should get a low ohm reading. At or very near zero. = Check very near zero
Now move the probe from the green wire to the body of the stator. This should give you a very high ohm reading, infinity would be ideal. = Check reading infinity
On the other brush touch one probe to the black wire at the brush and at the brown wire in the plug. This should get a low ohm reading. = Check very low near zero
Move the probe from the black brush wire and touch the stator. An high ohm reading here as with the green wire is good. = Check reading infinity
Now touch one probe to each slip ring on the rotor. = Reads exactly 5ohms (with correction for lead resistance)
Both brushes are a very good length.
You said the reading was "closed", which I took to mean a short circuit??? Language barrier here I think.
Yes, infinite reading is good!
DevonDel
XS650 Member
Hi Del,
check out 2many's enlarged photo in post #21 again, eh?
Then pound that sheetmetal thing back straight again and see if the problem goes away.
check out 2many's enlarged photo in post #21 again, eh?
Then pound that sheetmetal thing back straight again and see if the problem goes away.
You just bought this bike. Did you ever see it run or know if the charging system ever worked??
Unplug the rec/reg and see if that stops the fuse from blowing. If it does, then you know the rec/reg was defective when you bought the bike.
DevonDel
XS650 Member
Yep, already done and Leo's check list has proved that the brushes aren't shorting to the stator housing.
Still fuse blowing though....
Hi Del,
so long as you are confident in your checking methodology, it sure looks like the guard is bowed towards the brush wire close enough to touch it and thus provide a direct path to ground.
Then go with RG and unplug the reg/rect to see what happens.
And you don't need to keep blowing fuses.
Rig up a headlight bulb where the fuse should be.
If it lights up bright the circuit is still shorting.
so long as you are confident in your checking methodology, it sure looks like the guard is bowed towards the brush wire close enough to touch it and thus provide a direct path to ground.
Then go with RG and unplug the reg/rect to see what happens.
And you don't need to keep blowing fuses.
Rig up a headlight bulb where the fuse should be.
If it lights up bright the circuit is still shorting.
DevonDel
XS650 Member
Thank you all for help and advice, especially Leo. I followed the fault back up the system and the trail ended at the rec/reg which I replaced with a new FZ600 part.
No more blown fuses, charging well and regulating at 14.5v plus learn such a huge amount.....everyday is a school day.
No more blown fuses, charging well and regulating at 14.5v plus learn such a huge amount.....everyday is a school day.
