My jigsaw started sparking and throwing out smoke, so I took it to bits, found a shorted coil in the motor, and disconnected it. But it's still doing this (sew video). Is there anything that can be done, or does it go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

--
Many of the world's greatest runners come from Kenya because they have a unique training program there -- it's called a lion.

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is that wrong? And why would it still flash at the brushes when the shorted one is removed?

--
In the first few days of the Olympics the Rumanians took gold, silver, bronze, copper, lead and anything else they could get their bloody hands on.

On 08/05/2016 16:01, Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes when the
shorted one is removed?



Yawn. Replace the brushes. Yawn.

Or throw it.

On Sun, 08 May 2016 16:07:23 +0100, GB wrote:

On 08/05/2016 16:01, Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes when the
shorted one is removed?



Yawn. Replace the brushes. Yawn.

Tried that before on a brush cutter, but it didn't fix the problem. I was told the coils were shorting and that was busting the brushes. I got a warranty replacement.

In this case, the jigsaw DID have a shorted coil. Every coil was 1.15 ohms except one coil which was 0.1 ohms.

--
I had amnesia once -- or twice.

Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes when the
shorted one is removed?

Yes but 1 time in 24 the current is going from full to min and causing
the sparks.

On Sun, 08 May 2016 17:27:33 +0100, Bob Minchin wrote:

Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes when the
shorted one is removed?

Yes but 1 time in 24 the current is going from full to min and causing
the sparks.

I see. But presumably nothing like from full to short.

Repairing the coil would be impossible, the insulation is like glue, you can't unravel little motors like that.

--
Black.... like the clouds of death that follow me into the forest of doom and hide in the wardrobe of darkness! Blaaaackk!

Mr Macaw wrote:
On Sun, 08 May 2016 17:27:33 +0100, Bob Minchin
wrote:
Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it
to bits, found a shorted coil in the motor, and disconnected it. But
it's still doing this (sew video). Is there anything that
can be done, or does it go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes
when the shorted one is removed?

Yes but 1 time in 24 the current is going from full to min and
causing the sparks.

I see. But presumably nothing like from full to short.

Repairing the coil would be impossible, the insulation is like glue,
you can't unravel little motors like that.

Hmmm, seems like your 21 year old degree is as useless as you are.
You have been called a tool twice.
Allow me to call you a prick.

In message , Mr Pounder Esquire
writes
Yes but 1 time in 24 the current is going from full to min and
causing the sparks.

I see. But presumably nothing like from full to short.

Repairing the coil would be impossible, the insulation is like glue,
you can't unravel little motors like that.

Hmmm, seems like your 21 year old degree is as useless as you are.
You have been called a tool twice.
Allow me to call you a prick.

None of my business but anything that looks like a shorted turn does
annoying things with an alternating magnetic field:-(



--
Tim Lamb

"Mr Pounder Esquire" wrote in message
...
Mr Macaw wrote:
On Sun, 08 May 2016 17:27:33 +0100, Bob Minchin
wrote:
Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it
to bits, found a shorted coil in the motor, and disconnected it. But
it's still doing this (sew video). Is there anything that
can be done, or does it go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time. How is
that wrong? And why would it still flash at the brushes
when the shorted one is removed?

Yes but 1 time in 24 the current is going from full to min and
causing the sparks.

I see. But presumably nothing like from full to short.

Repairing the coil would be impossible, the insulation is like glue,
you can't unravel little motors like that.

Hmmm, seems like your 21 year old degree is as useless as you are.
You have been called a tool twice.
Allow me to call you a prick.

I am sure that many kettles have an opinion on that.

--
Adam

ARW wrote:
"Mr Pounder Esquire" wrote in message
...
Mr Macaw wrote:
On Sun, 08 May 2016 17:27:33 +0100, Bob Minchin
wrote:
Mr Macaw wrote:
On Sun, 08 May 2016 15:49:10 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it
to bits, found a shorted coil in the motor, and disconnected
it. But it's still doing this (sew video). Is there anything
that can be done, or does it go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

You need to repair the coil not remove it.

Removing it makes the motor provide force 23/24ths of the time.
How is that wrong? And why would it still flash at the brushes
when the shorted one is removed?

Yes but 1 time in 24 the current is going from full to min and
causing the sparks.

I see. But presumably nothing like from full to short.

Repairing the coil would be impossible, the insulation is like glue,
you can't unravel little motors like that.

Hmmm, seems like your 21 year old degree is as useless as you are.
You have been called a tool twice.
Allow me to call you a prick.

I am sure that many kettles have an opinion on that.

Kettles do not post here, thicko.

On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

On Sun, 08 May 2016 21:22:18 +0100, newshound wrote:

On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

It's a "Challenge" from Argos. Not a big brand.

--
Bill Clinton thinks "harass" is two words.

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the latter.

On Sunday, 8 May 2016 23:03:49 UTC+1, Fredxxx wrote:
On 08/05/2016 15:23, Mr Macaw wrote:

My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the latter..

There's always the horrible bodge option. Run the thing in series with a 3kW fire. If it still sparks too much, reduce the fire power. Of course it'll affect the motor speed & power some, but not greatly. And you'll probably find that 1 time in 24 it won't self start until moved slightly.


NT

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

If its a decent jigsaw, then replace the armature. If not, bin it.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Needs rewinding, probably not worth doing just get another one.
The reason why it happened in the first place might be nice to know for
future proofing the new one!

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Mr Macaw" wrote in message news
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it go
in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

--
Many of the world's greatest runners come from Kenya because they have a
unique training program there -- it's called a lion.

On 5/8/2016 10:14 PM, Mr Macaw wrote:
On Sun, 08 May 2016 21:22:18 +0100, newshound
wrote:

On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

It's a "Challenge" from Argos. Not a big brand.

Looks like a Bosch to me.

On 5/8/2016 11:51 PM, John Rumm wrote:
On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

If its a decent jigsaw, then replace the armature. If not, bin it.


+1

On Mon, 09 May 2016 10:23:40 +0100, newshound wrote:

On 5/8/2016 10:14 PM, Mr Macaw wrote:
On Sun, 08 May 2016 21:22:18 +0100, newshound
wrote:

On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

It's a "Challenge" from Argos. Not a big brand.

Looks like a Bosch to me.

No, unless Bosch are in the habit of selling off QC failed items to Argos?

--
Times are tough.
Just the other day, I saw a beggar who was so broke that he was standing on the corner shouting at the cars that went by.
He was shouting, "WILL WORK FOR CARDBOARD AND A MAGIC MARKER!"

On Sun, 08 May 2016 23:51:49 +0100, John Rumm wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

If its a decent jigsaw, then replace the armature. If not, bin it.

For an expensive jigsaw, you can actually buy an armature for significantly less than the price of the whole tool? Isn't it the most expensive part?

--
Dijon vu: the same mustard as before.

Why can't I disconnect the shorted coil?

The reason is it's ****. The motor can't have had adequate cooling. I was using it to cut wood, without pushing it hard, for about 10 minutes, with a 50% duty cycle.


On Mon, 09 May 2016 08:34:06 +0100, Brian Gaff wrote:

Needs rewinding, probably not worth doing just get another one.
The reason why it happened in the first place might be nice to know for
future proofing the new one!

Brian



--
A farmer in Yorkshire sees a bloke drinking from his stream and shouts, €œEy up cocker, tha dunt wanna be drinkin watta frum theer, its full o hoss **** an cow ****e an it could kill thee.€�
The Bloke says, "Sir I am a muslim from Pakistan, can you be speaking clearer and slower please.€�
The farmer replies, "If.... You.... Use.... Two.... Hands.... You.... Won't.... Spill.... Any."

Mr Macaw wrote

Why can't I disconnect the shorted coil?

You can, but it wont work properly when you do.

That coil is there for a reason.

The reason is it's ****. The motor can't have had adequate cooling.

Or it failed for a different reason.

I was using it to cut wood, without pushing it hard,
for about 10 minutes, with a 50% duty cycle.

And the coil may not have been made properly.

Brian Gaff wrote

Needs rewinding, probably not worth doing just get another one.
The reason why it happened in the first place might be nice to know for
future proofing the new one!

On 10/05/2016 23:10, Mr Macaw wrote:
On Sun, 08 May 2016 23:51:49 +0100, John Rumm
wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

If its a decent jigsaw, then replace the armature. If not, bin it.

For an expensive jigsaw, you can actually buy an armature for
significantly less than the price of the whole tool? Isn't it the most
expensive part?

You can usually get armatures - they are one of the more expensive bits,
although with jigsaws the gearbox may cost more.


e.g. for:

http://www.lawson-his.co.uk/makita-4...-and-carrycase

A new armature is £40:

http://www.mtmc.co.uk/Spare-Parts/Ma...296-75050.aspx

(see item 62)

Depending on model it might be more or less.

I bought a new armature for my SDS a while back, that was £26 inc
delivery - certainly better than £100 for a new drill.

http://wiki.diyfaq.org.uk/index.php/...re_Replacement


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the latter.

Couldn't I short a winding 180 degrees round from the already shorted one?

--
I learnt so much from my mistakes I think I'll make another.

On Sun, 08 May 2016 23:23:37 +0100, wrote:

On Sunday, 8 May 2016 23:03:49 UTC+1, Fredxxx wrote:
On 08/05/2016 15:23, Mr Macaw wrote:

My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the latter.

There's always the horrible bodge option. Run the thing in series with a 3kW fire. If it still sparks too much, reduce the fire power. Of course it'll affect the motor speed & power some, but not greatly. And you'll probably find that 1 time in 24 it won't self start until moved slightly.

Thanks, I'll try that.

--
Why was the "pap smear" called that?
If it'd been called the "**** Scrape," no one would ever have it done.

On Wed, 11 May 2016 10:31:16 +0100, Rod Speed wrote:

Mr Macaw wrote

Why can't I disconnect the shorted coil?

You can, but it wont work properly when you do.

That coil is there for a reason.

The reason is it's ****. The motor can't have had adequate cooling.

Or it failed for a different reason.

Like?

I was using it to cut wood, without pushing it hard,
for about 10 minutes, with a 50% duty cycle.

And the coil may not have been made properly.

The motor was too hot to touch for some time afterwards. That can't be right.

Brian Gaff wrote

Needs rewinding, probably not worth doing just get another one.
The reason why it happened in the first place might be nice to know for
future proofing the new one!



--
Jazz is what you get when you push a blues quartet down a long flight of stairs.

"Mr Macaw" wrote in message news
On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted one?

You could, but you'd still get that arcing.

Mr Macaw wrote
Rod Speed wrote
Mr Macaw wrote

Why can't I disconnect the shorted coil?

You can, but it wont work properly when you do.

That coil is there for a reason.

The reason is it's ****. The motor can't have had adequate cooling.

Or it failed for a different reason.

Like?

The insulation may have been nicked by the machine that made it etc.

I was using it to cut wood, without pushing it hard,
for about 10 minutes, with a 50% duty cycle.

And the coil may not have been made properly.

The motor was too hot to touch for some time afterwards. That can't be
right.

That may well just be a side effect of the
failure and not the cause of the failure.

Brian Gaff wrote

Needs rewinding, probably not worth doing just get another one.
The reason why it happened in the first place might be nice to know
for
future proofing the new one!

On Fri, 13 May 2016 06:44:02 +0100, Rod Speed wrote:



"Mr Macaw" wrote in message news
On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted one?

You could, but you'd still get that arcing.

Why? Changing 12 coils in series to 11 coils in series doesn't change much surely?

--
Anybody who claims that marriage is a fifty-fifty proposition doesn't know a damned thing about women or fractions.

"Mr Macaw" wrote in message news
On Fri, 13 May 2016 06:44:02 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news
On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

On Sat, 14 May 2016 04:33:16 +0100, Rod Speed wrote:



"Mr Macaw" wrote in message news
On Fri, 13 May 2016 06:44:02 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance between the brushes is always around 15 ohms, and 1.1 ohm between neighbouring contacts on the commutator.

--
What should you do if your girlfriend starts smoking during sex?
Slow down and use a lubricant.

"Mr Macaw" wrote in message news
On Sat, 14 May 2016 04:33:16 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news
On Fri, 13 May 2016 06:44:02 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be getting
arcing.

On Mon, 16 May 2016 03:37:19 +0100, Rod Speed wrote:



"Mr Macaw" wrote in message news
On Sat, 14 May 2016 04:33:16 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Fri, 13 May 2016 06:44:02 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be getting
arcing.

Indeed, I don't understand what's causing the arcing. I'll check the brush to brush resistances again then try new brushes (even though they look ok).

--
English German
Indicators ---- Die Blinkenleiten Tickentocken
Bonnet ---- Pullnob und Knucklechopper
Exhaust ---- Die Spitzenpoppenbangentuben
Speedometer ---- Der Egobooster und Linenshooter
Clutch ---- Die Kuplink mit schlippen und shaken
Puncture ---- Die Phlatt mit Bludy****en
Learner Driver ---- Die ****ten mit Elplatz
Estate Car ---- Der Bagmooroomfurshagginauto
Parking Meter ---- Der Tennerpinscher und Klockenwerr
Windscreen Wiper ---- Der Flippenflappenmuckenschpredder
Footbrake ---- Der Edbangeronvindschreen Stoppend
Gear Lever ---- Biggen Sticken fur Kangaroochoppen
Breathalyser ---- Die Pu titintem fur Pistenarsen
Seat Belt ---- Der Klunkenklikker Frauleintrapper
Headlights ---- Das Dippendontdazzleyubastad
Exhaust Fumes ---- Der Koffenundschpittpoluter
Highway Code ---- Der Wipan fur Arsen
Fog Warning ---- Die Puttenlegdownen und Fukkit
Traffic Jam ---- Die Bluddifukkink Dammundblast
Rear Seat ---- Der Schpringentester
Backfire ---- Der Lowdenbangenmekkenjumpen
Articulated Lorry ---- Der Fukkengrett Trukken
Accident ---- Der Bleedinmess
Near Accident ---- Der Fukken Near Schittsenselfen
Service Station ---- Der Heiway Robberungen
Cyclist ---- Der Pedallpushink Pilloken
Double White lines ---- Overtakenund Krunchen

Mr Macaw wrote:
On Mon, 16 May 2016 03:37:19 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news
On Sat, 14 May 2016 04:33:16 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Fri, 13 May 2016 06:44:02 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx
wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or
does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already
shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be
getting
arcing.

Indeed, I don't understand what's causing the arcing. I'll check the
brush to brush resistances again then try new brushes (even though they
look ok).

You will not be able to tell what is going on with dc resistance checks.
The problem seems to be shorted turns and even if you disconnect that
part of the winding the short is still there and high current will flow
when that part of the winding has a current induced in it.

Either just give up and throw it away or use it as an exercise to
properly understand how motors and their fault conditions work.

If you can find someone with a machine called a "growler" this can be
used to show shorted turns. Google.

In article ,
newshound wrote:
On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

Really? Bought some plastic parts for my Bosch jigsaw when the blade
locking mechanism failed. I thought the price silly.

--
*Sometimes I wake up grumpy; Other times I let him sleep.

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 16 May 2016 13:44:02 +0100, Dave Plowman (News) wrote:

In article ,
newshound wrote:
On 5/8/2016 3:23 PM, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to bits,
found a shorted coil in the motor, and disconnected it. But it's still
doing this (sew video). Is there anything that can be done, or does it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0


Bosch spares are usually readily available, and not too expensive.

Really? Bought some plastic parts for my Bosch jigsaw when the blade
locking mechanism failed. I thought the price silly.

Funny, that's exactly the part that failed on my Bosch, hence I bought a cheap **** one next. I couldn't get a spare.

--
If breasts had no nipples, they'd be pointless.

On Mon, 16 May 2016 12:16:41 +0100, Bob Minchin wrote:

Mr Macaw wrote:
On Mon, 16 May 2016 03:37:19 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sat, 14 May 2016 04:33:16 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Fri, 13 May 2016 06:44:02 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx
wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took it to
bits,
found a shorted coil in the motor, and disconnected it. But it's
still
doing this (sew video). Is there anything that can be done, or
does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour the
latter.

Couldn't I short a winding 180 degrees round from the already
shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be
getting
arcing.

Indeed, I don't understand what's causing the arcing. I'll check the
brush to brush resistances again then try new brushes (even though they
look ok).

You will not be able to tell what is going on with dc resistance checks.
The problem seems to be shorted turns and even if you disconnect that
part of the winding the short is still there and high current will flow
when that part of the winding has a current induced in it.

Either just give up and throw it away or use it as an exercise to
properly understand how motors and their fault conditions work.

If you can find someone with a machine called a "growler" this can be
used to show shorted turns. Google.

If induced currents are going to cause a problem, I may well just give up. I guess it's like a transformer with a shorted output.

--
If quizzes are quizzical, what are tests?

Mr Macaw wrote:
On Mon, 16 May 2016 12:16:41 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
On Mon, 16 May 2016 03:37:19 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sat, 14 May 2016 04:33:16 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Fri, 13 May 2016 06:44:02 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx
wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took
it to
bits,
found a shorted coil in the motor, and disconnected it. But
it's
still
doing this (sew video). Is there anything that can be done, or
does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour
the
latter.

Couldn't I short a winding 180 degrees round from the already
shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change
much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be
getting
arcing.

Indeed, I don't understand what's causing the arcing. I'll check the
brush to brush resistances again then try new brushes (even though they
look ok).

You will not be able to tell what is going on with dc resistance checks.
The problem seems to be shorted turns and even if you disconnect that
part of the winding the short is still there and high current will flow
when that part of the winding has a current induced in it.

Either just give up and throw it away or use it as an exercise to
properly understand how motors and their fault conditions work.

If you can find someone with a machine called a "growler" this can be
used to show shorted turns. Google.

If induced currents are going to cause a problem, I may well just give
up. I guess it's like a transformer with a shorted output.

Yes that is exactly what is going on.
To be honest the design margins on these sort of motors are so so tight
they are almost bound to fail at some stage the only unknown is when!

On Mon, 16 May 2016 17:08:11 +0100, Bob Minchin wrote:

Mr Macaw wrote:
On Mon, 16 May 2016 12:16:41 +0100, Bob Minchin
wrote:

Mr Macaw wrote:
On Mon, 16 May 2016 03:37:19 +0100, Rod Speed
wrote:



"Mr Macaw" wrote in message
news On Sat, 14 May 2016 04:33:16 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Fri, 13 May 2016 06:44:02 +0100, Rod Speed

wrote:



"Mr Macaw" wrote in message
news On Sun, 08 May 2016 23:03:48 +0100, Fredxxx
wrote:

On 08/05/2016 15:23, Mr Macaw wrote:
My jigsaw started sparking and throwing out smoke, so I took
it to
bits,
found a shorted coil in the motor, and disconnected it. But
it's
still
doing this (sew video). Is there anything that can be done, or
does
it
go in the bucket?

https://www.dropbox.com/s/75z1zyve3jajgg7/Saw.AVI?dl=0

Consider the armature approximating a rotating transformer.

One segment that has a short is like shorting a winding in a
transformer.

Either get a new armature, or get a new jigsaw. I would favour
the
latter.

Couldn't I short a winding 180 degrees round from the already
shorted
one?

You could, but you'd still get that arcing.

Why?

Because that is how those motors work.

Changing 12 coils in series to 11 coils in series doesn't change
much
surely?

It isn't 11 coils in series. A much smaller number is electrically
connected
at a particular
time and the arcing is due to the fact that the one coil is a sort
currently.

I can't see how they're wired, but I can tell you that the resistance
between the brushes is always around 15 ohms, and 1.1 ohm between
neighbouring contacts on the commutator.

If that was true in all positions of what rotates, you wouldn't be
getting
arcing.

Indeed, I don't understand what's causing the arcing. I'll check the
brush to brush resistances again then try new brushes (even though they
look ok).

You will not be able to tell what is going on with dc resistance checks.
The problem seems to be shorted turns and even if you disconnect that
part of the winding the short is still there and high current will flow
when that part of the winding has a current induced in it.

Either just give up and throw it away or use it as an exercise to
properly understand how motors and their fault conditions work.

If you can find someone with a machine called a "growler" this can be
used to show shorted turns. Google.

If induced currents are going to cause a problem, I may well just give
up. I guess it's like a transformer with a shorted output.

Yes that is exactly what is going on.
To be honest the design margins on these sort of motors are so so tight
they are almost bound to fail at some stage the only unknown is when!

They always fail when overworked. If they had better cooling, they wouldn't fail. I find it amusing when one fails just after I've bought it. I get another under warranty at their expense. Maybe one day they'll learn.

--
There are 2 kinds of people in this world. Those that want to get ahead, and those that just want to get head.