whats the difference between an AC Ignition coil and a DC one?

[Gunner Asch]

Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.

I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.

Im testing the electrical with a 6vt battery charger hooked into place
of the battery

The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.

Whats the difference between an AC and a DC coil????

Anyone got a surplus manual for a 1974-75 Honda XL 350?

Gunner

"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

[Terry Coombs]

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

Gunner , think about it for a minute - if that voltage input to the coil
was AC , it'd be buzzin' all the time . There's gotta be a diode , or more
likely a plate rectifier (My '74 CB750 has one of those on the 3 phase
output from the alt coils) between that coil and the supply .

And a metal-filled epoxy on a high-voltage application ? The weak spark is
more likely from a bad cap . Do ya get like a giant spark when ya break the
circuit ? Sure sign of a bad cap .

[Gunner Asch]

On Sun, 23 Nov 2008 15:23:07 -0600, "Terry Coombs"

Post by Terry Coombs

Post by Gunner Asch
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

Gunner , think about it for a minute - if that voltage input to the coil
was AC , it'd be buzzin' all the time . There's gotta be a diode , or more
likely a plate rectifier (My '74 CB750 has one of those on the 3 phase
output from the alt coils) between that coil and the supply .
And a metal-filled epoxy on a high-voltage application ? The weak spark is
more likely from a bad cap . Do ya get like a giant spark when ya break the
circuit ? Sure sign of a bad cap .
--
Snag
sometimes ya gotta
shovel manure
to pay the bills

Here is the wiring diagram...check it out for yourself

Loading Image...

Thanks guys for the heads up on JB Weld..Id not remembered that it was
metal filled.

Gunner

[Terry Coombs]

Post by Gunner Asch
On Sun, 23 Nov 2008 15:23:07 -0600, "Terry Coombs"

Post by Terry Coombs

Post by Gunner Asch
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil
for $21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

Gunner , think about it for a minute - if that voltage input to the
coil was AC , it'd be buzzin' all the time . There's gotta be a
diode , or more likely a plate rectifier (My '74 CB750 has one of
those on the 3 phase output from the alt coils) between that coil
and the supply .
And a metal-filled epoxy on a high-voltage application ? The weak
spark is more likely from a bad cap . Do ya get like a giant spark
when ya break the circuit ? Sure sign of a bad cap .
--
Snag
sometimes ya gotta
shovel manure
to pay the bills

Here is the wiring diagram...check it out for yourself
http://www.cmsnl.com/classic-honda-fansite/honda_wiring_diagrams/XL350.jpg
Thanks guys for the heads up on JB Weld..Id not remembered that it was
metal filled.
Gunner

If I'd had my head in the light , I'd have realized that the ignition
system is basically a magneto with the coils in separate units .
Hey , embarassment can lead to learning too !

[Cliff]

Post by Terry Coombs
Gunner , think about it for a minute - if that voltage input to the coil
was AC , it'd be buzzin' all the time . There's gotta be a diode , or more
likely a plate rectifier (My '74 CB750 has one of those on the 3 phase
output from the alt coils) between that coil and the supply .

Magneto.

[Terry Coombs]

Post by Gunner Asch
On Sun, 23 Nov 2008 15:23:07 -0600, "Terry Coombs"

Post by Terry Coombs
Gunner , think about it for a minute - if that voltage input to the
coil was AC , it'd be buzzin' all the time . There's gotta be a
diode , or more likely a plate rectifier (My '74 CB750 has one of
those on the 3 phase output from the alt coils) between that coil
and the supply .

Magneto.

Yer a bit late Cliffy . I figured that out about ten hours ago .

[Cliff]

Post by Terry Coombs

Post by Gunner Asch
On Sun, 23 Nov 2008 15:23:07 -0600, "Terry Coombs"

Post by Terry Coombs
Gunner , think about it for a minute - if that voltage input to the
coil was AC , it'd be buzzin' all the time . There's gotta be a
diode , or more likely a plate rectifier (My '74 CB750 has one of
those on the 3 phase output from the alt coils) between that coil
and the supply .

Magneto.

Yer a bit late Cliffy . I figured that out about ten hours ago .

IIRC I'd posted the same thing to an earlier thread of Gunner's on
the same subject.

DC or AC .... it's the change in current flow that matters
in a transformer.
A "DC" one might need higher heat removal though due
to a possible constant average base current resistive energy loss.
Design issue.

[Terry Coombs]

On Mon, 24 Nov 2008 15:13:15 -0600, "Terry Coombs"

Post by Terry Coombs

Post by Gunner Asch
On Sun, 23 Nov 2008 15:23:07 -0600, "Terry Coombs"

Post by Terry Coombs
Gunner , think about it for a minute - if that voltage input to
the coil was AC , it'd be buzzin' all the time . There's gotta be a
diode , or more likely a plate rectifier (My '74 CB750 has one of
those on the 3 phase output from the alt coils) between that coil
and the supply .

Magneto.

Yer a bit late Cliffy . I figured that out about ten hours ago .

IIRC I'd posted the same thing to an earlier thread of Gunner's on
the same subject.

I missed that .

DC or AC .... it's the change in current flow that matters
in a transformer.

And thus my questioning of an AC ignition coil . Until I realizes it was a
form of magneto .

A "DC" one might need higher heat removal though due
to a possible constant average base current resistive energy loss.
Design issue.

That is related to dwell time , and is indeed a design issue . I'm not a
designer , just a user - B&S , Tecumsah ...

[Cliff]

Post by Terry Coombs

Post by Cliff
DC or AC .... it's the change in current flow that matters
in a transformer.

And thus my questioning of an AC ignition coil . Until I realizes it was a
form of magneto .

He may have to charge any battery from his wall socket <G>.

[Cliff]

Post by Terry Coombs

Post by Cliff

Post by Terry Coombs
Yer a bit late Cliffy . I figured that out about ten hours ago .

IIRC I'd posted the same thing to an earlier thread of Gunner's on
the same subject.

I missed that .

It might not have been xposted the same way; I dunno.

[Rick]

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

I've got a bit of info on the XL250 from an old Chilton, but nothing on the 350. Indeed,
the wiring diagram shows a separate winding on the alternator for the ignition and an "AC
ignition coil"-no rectifiers. You should be able to rewire so to use a regular 6V coil. I
can try to scan the wiring diagram and send that to you if it's any help, but there's
nothing in the Chilton about that alternator.

[Terry Coombs]

Post by Rick

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil
for $21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

I've got a bit of info on the XL250 from an old Chilton, but nothing
on the 350. Indeed, the wiring diagram shows a separate winding on
the alternator for the ignition and an "AC ignition coil"-no
rectifiers. You should be able to rewire so to use a regular 6V coil.
I can try to scan the wiring diagram and send that to you if it's any
help, but there's nothing in the Chilton about that alternator.

I'd sure like to see details of that system ! How do they time the spark ?
Kinda makes sense , AC will give a continuous spark , or rather arc ? Learn
something new every day !

[Rick]

Post by Terry Coombs

Post by Rick

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil
for $21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

I've got a bit of info on the XL250 from an old Chilton, but nothing
on the 350. Indeed, the wiring diagram shows a separate winding on
the alternator for the ignition and an "AC ignition coil"-no
rectifiers. You should be able to rewire so to use a regular 6V coil.
I can try to scan the wiring diagram and send that to you if it's any
help, but there's nothing in the Chilton about that alternator.

I'd sure like to see details of that system ! How do they time the spark ?
Kinda makes sense , AC will give a continuous spark , or rather arc ? Learn
something new every day !
--
Snag
sometimes ya gotta
shovel manure
to pay the bills

It appears to be essentially a magneto winding..still uses points and a condenser.

[Jon Anderson]

Not sure of the difference but there surely is one. The old Ducati
singles used both. Street bikes with batteries had the DC coil, the
scramblers with magnetos had an AC coil. If you need an AC coil, try
some motorcycle boneyards and look for dirt bikes, which generally all
run mags. Also, I'll bet you could find a used coil on ebay for far less
than the dealer wants.

Speaking of which, I remember Dirt Bike magazine running an article in I
think the late 70's, touting how anyone could have their own $10,000 MX
bike. Back then, those dollars meant works bikes. Well, all one had to
do to own such an expensive bike was buy it one single part at a time.
The markup is huge!

Jon

[nick hull]

Post by Jon Anderson
Speaking of which, I remember Dirt Bike magazine running an article in I
think the late 70's, touting how anyone could have their own $10,000 MX
bike. Back then, those dollars meant works bikes. Well, all one had to
do to own such an expensive bike was buy it one single part at a time.
The markup is huge!

The markup on parts is usually more than the markup on the whole ;(

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

[Wayne]

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

If the battery is used for the ignition, which I don't know that is or
not, then you'll probably need a battery, not a battery charger.

You can see a listing of parts here
http://www.bikebandit.com/houseofmotorcycles/honda-motorcycle-xl350-1974/o/m9383

[Steve W.]

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to

Check your Email

[c***@snyder.on.ca]

On Sun, 23 Nov 2008 13:06:24 -0800, Gunner Asch

Post by Gunner Asch
Im puttering around with the 1974 Honda XL 350...and the coil puts out a
weak spark...It may have something to do with the fact the lead wire to
the plug is only held on with the internal wire..the insulation is
broken around where its molded into the coil itself. I suppose I could
repair that with JB weld. The condenser is also molded as part of the
coil, and it may be bad, so I picked up a used condenser from a bike
yard and will splice it in.

Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Post by Gunner Asch
I picked up a used generic 6vt coil for $10, and machined a mount to
adapt it to the bike. I tested the coil by grounding the hot lead by
scratching it to the frame and after 10 or 15 sparks, the coil split
around the circumference . It doesnt spark anymore...shrug. It had no
condenser attached to it. It "bumped" pretty good each time I sparked
it. Had a nice brite spark too.
Im testing the electrical with a 6vt battery charger hooked into place
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????
Anyone got a surplus manual for a 1974-75 Honda XL 350?
Gunner
"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

[[e-mail]]

Post by c***@snyder.on.ca
Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Being the curious type, and having seen before the statement about JB
weld being slightly conductive, I decided to see if it was true.

I have a number of pallets made of scrap circuit board material and JB
Weld epoxy. The pallets carry circuit boards or panels of boards
through our convection oven to solder the surface mount components to
the boards. We use both leaded and lead free solder paste, so it gets
very hot. JB Weld is the only common epoxy that will stand the heat
over and over.

I checked the JB Weld on a pallet with a hand held DVM set to read 20
meg ohms. No matter how close I set the test leads, they showed a
complete open circuit. If JB Weld is slightly conductive, it must be
extremely slight!!! It should work just fine to repair electrical
parts, including ignition coils.

Paul

[Steve W.]

Post by ***@coinet.com

Post by c***@snyder.on.ca
Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Being the curious type, and having seen before the statement about JB
weld being slightly conductive, I decided to see if it was true.
I have a number of pallets made of scrap circuit board material and JB
Weld epoxy. The pallets carry circuit boards or panels of boards
through our convection oven to solder the surface mount components to
the boards. We use both leaded and lead free solder paste, so it gets
very hot. JB Weld is the only common epoxy that will stand the heat
over and over.
I checked the JB Weld on a pallet with a hand held DVM set to read 20
meg ohms. No matter how close I set the test leads, they showed a
complete open circuit. If JB Weld is slightly conductive, it must be
extremely slight!!! It should work just fine to repair electrical
parts, including ignition coils.
Paul

Now try it while running 20-30 kv though it.
It's amazing how items that show no conductivity at 9 volts conduct just
fine at high voltage.

[[e-mail]]

Post by Steve W.

Post by ***@coinet.com

Post by c***@snyder.on.ca
Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Being the curious type, and having seen before the statement about JB
weld being slightly conductive, I decided to see if it was true.
I have a number of pallets made of scrap circuit board material and JB
Weld epoxy. The pallets carry circuit boards or panels of boards
through our convection oven to solder the surface mount components to
the boards. We use both leaded and lead free solder paste, so it gets
very hot. JB Weld is the only common epoxy that will stand the heat
over and over.
I checked the JB Weld on a pallet with a hand held DVM set to read 20
meg ohms. No matter how close I set the test leads, they showed a
complete open circuit. If JB Weld is slightly conductive, it must be
extremely slight!!! It should work just fine to repair electrical
parts, including ignition coils.
Paul

Now try it while running 20-30 kv though it.
It's amazing how items that show no conductivity at 9 volts conduct just
fine at high voltage.
--
Steve W.
Near Cooperstown, New York

That's true, Steve. But is the base material conducting or is it the
surface contamination?

Paul

[Steve W.]

Post by ***@coinet.com

Post by Steve W.

Post by ***@coinet.com

Post by c***@snyder.on.ca
Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Being the curious type, and having seen before the statement about JB
weld being slightly conductive, I decided to see if it was true.
I have a number of pallets made of scrap circuit board material and JB
Weld epoxy. The pallets carry circuit boards or panels of boards
through our convection oven to solder the surface mount components to
the boards. We use both leaded and lead free solder paste, so it gets
very hot. JB Weld is the only common epoxy that will stand the heat
over and over.
I checked the JB Weld on a pallet with a hand held DVM set to read 20
meg ohms. No matter how close I set the test leads, they showed a
complete open circuit. If JB Weld is slightly conductive, it must be
extremely slight!!! It should work just fine to repair electrical
parts, including ignition coils.
Paul

Now try it while running 20-30 kv though it.
It's amazing how items that show no conductivity at 9 volts conduct just
fine at high voltage.
--
Steve W.
Near Cooperstown, New York

That's true, Steve. But is the base material conducting or is it the
surface contamination?
Paul

When the voltage burns through it in multiple places I would say the
problem is the base material. It doesn't insulate high voltage very well.
I have tried JB weld for this same application. It burned through and
arced from the moment the current hit the repair.

[[e-mail]]

Post by Steve W.

Post by ***@coinet.com

Post by Steve W.

Post by ***@coinet.com

Post by c***@snyder.on.ca
Do NOT use JB weld, it is metal filled and slightly conductive. Best
is plasic bumper repair epoxy, or winsheild mounting urethane. Plain
epoxy works pretty well too, but the bumper stuff stays flexible.

Being the curious type, and having seen before the statement about JB
weld being slightly conductive, I decided to see if it was true.
I have a number of pallets made of scrap circuit board material and JB
Weld epoxy. The pallets carry circuit boards or panels of boards
through our convection oven to solder the surface mount components to
the boards. We use both leaded and lead free solder paste, so it gets
very hot. JB Weld is the only common epoxy that will stand the heat
over and over.
I checked the JB Weld on a pallet with a hand held DVM set to read 20
meg ohms. No matter how close I set the test leads, they showed a
complete open circuit. If JB Weld is slightly conductive, it must be
extremely slight!!! It should work just fine to repair electrical
parts, including ignition coils.
Paul

Now try it while running 20-30 kv though it.
It's amazing how items that show no conductivity at 9 volts conduct just
fine at high voltage.
--
Steve W.
Near Cooperstown, New York

That's true, Steve. But is the base material conducting or is it the
surface contamination?
Paul

When the voltage burns through it in multiple places I would say the
problem is the base material. It doesn't insulate high voltage very well.
I have tried JB weld for this same application. It burned through and
arced from the moment the current hit the repair.
--
Steve W.
Near Cooperstown, New York

I suppose some would accuse us of hijacking Gunner's post, but some
may learn from our discussion.

Probably any regular epoxy would fail when the voltage is sufficient.
We have a customer that must test his circuit boards at 6kv. His new
design arc'd between leads of through-hole resistors. A quick fix
using corona dope was tried. Didn't work. More layers of corona dope.
Still arced. Had to do a board redesign to reorient the resistors to
give about 3/4 inch spacing between leads. That to cured the problem.

I don't know what is in corona dope, but in the 1950's we used to
repair TV flyback transformers with it. Why it didn't work on the
resistors is unknown.

Paul

[Steve W.]

Post by ***@coinet.com
I suppose some would accuse us of hijacking Gunner's post, but some
may learn from our discussion.
Probably any regular epoxy would fail when the voltage is sufficient.
We have a customer that must test his circuit boards at 6kv. His new
design arc'd between leads of through-hole resistors. A quick fix
using corona dope was tried. Didn't work. More layers of corona dope.
Still arced. Had to do a board redesign to reorient the resistors to
give about 3/4 inch spacing between leads. That to cured the problem.
I don't know what is in corona dope, but in the 1950's we used to
repair TV flyback transformers with it. Why it didn't work on the
resistors is unknown.
Paul

One of my former jobs was testing the insulation on some motor housings,
we tested at 20kv normally. I got to "play" with other insulating
materials as well.

Most corona dope is nothing but a thick enamel or solvent dissolved
polystyrene material. About 4kv per mil was the rating on the stuff I
used. The problem in your case may have simply been that the hole
spacing was tight enough that no insulation would have worked unless you
could make the arc path itself longer.

One of the other folks in our plant used to say that the testing I was
doing was scary. Then I mentioned that the powder gun he used daily ran
at a 40kv charge. His eyes turned into saucers then.

[Joseph Gwinn]

In article
<1133d768-41dc-4da2-9563-***@n33g2000pri.googlegroups.com>,
"***@coinet.com" <***@yahoo.com> wrote:


[snip]

Post by ***@coinet.com
I don't know what is in corona dope, but in the 1950's we used to
repair TV flyback transformers with it. Why it didn't work on the
resistors is unknown.

It's a polyurethane varnish. Google on "corona dope", go to the
GC/Waldon website, and look at the MSDS.

Joe Gwinn

[Cliff]

Post by ***@coinet.com
Probably any regular epoxy would fail when the voltage is sufficient.
We have a customer that must test his circuit boards at 6kv. His new
design arc'd between leads of through-hole resistors. A quick fix
using corona dope was tried. Didn't work. More layers of corona dope.
Still arced. Had to do a board redesign to reorient the resistors to
give about 3/4 inch spacing between leads. That to cured the problem.

Sharp points on the ends of the leads?

[Cliff]

Post by ***@coinet.com
I don't know what is in corona dope, but in the 1950's we used to
repair TV flyback transformers with it.

Not a great deal of voltage between turns of the coil.

[Cliff]

Post by Steve W.
When the voltage burns through it in multiple places I would say the
problem is the base material.

Might have some conductive fillers?

[Cliff]

Post by Steve W.
Now try it while running 20-30 kv though it.
It's amazing how items that show no conductivity at 9 volts conduct just
fine at high voltage.

Breakdown voltages are not "conductive epoxy".

[John Scheldroup]

Post by Gunner Asch
Whats the difference between an AC and a DC coil????

Depends 1 phase or 3 phase? remember stator <bridge circuit> rectifier/regulate

[K Ludger]

Post by Gunner Asch
of the battery
The wiring diagram I have and all references say that the Honda uses an
AC coil, fed by an ignition winding on the alternator. Honda wants $80
for a replacement coil, JC Whitney sells an aftermarket "can" coil for
$21, but doesnt indicate if its AC or DC.
Whats the difference between an AC and a DC coil????

Maybe waaaaaaay off course - could the AC refer to AC Delco rather than A.C.
// D.C.

The AC / DC doesn't make much sense. AFAIK the primary difference with older
(car) coils was if they had in internal or external ballast resistor.