12 volt cylindrical ignition coil

Mr. T. Minnesota · Mar 21, 2014

Forum Members,
Question concerns a JD lawn tractor with a cylindrical 12 volt coil. Does a coil of this type have to be grounded to function? Reason for the question is I had trouble starting the JD in weeks past and eventually found the coil had become detached from the block. There were other possible reasons for not starting and thought this may be one. Any and all thoughts welcome!
Mr. T. Minnesota

JMOR · Mar 21, 2014

(quoted from post at 19:28:02 03/21/14) Forum Members,
Question concerns a JD lawn tractor with a cylindrical 12 volt coil. Does a coil of this type have to be grounded to function? Reason for the question is I had trouble starting the JD in weeks past and eventually found the coil had become detached from the block. There were other possible reasons for not starting and thought this may be one. Any and all thoughts welcome!
Mr. T. Minnesota

ost coils do not need a case ground, but..........there are exceptions and one I can name is a Honda 50 3 wheeler.

BillM (OH) · Mar 21, 2014

It may have loosened one or more of the connections when it came loose, but it does not have to be grounded as far as I know. No expert on JD's by any means

gears · Mar 21, 2014

Nope it's grounded via the points. POS hot with ign on and points open and close the circuit firing the coil.

Now a busted mount may've allowed the hot post to short against a shroud or the block killing your spark.

JMOR · Mar 21, 2014

(quoted from post at 19:34:47 03/21/14) Nope it's grounded via the points. POS hot with ign on and points open and close the circuit firing the coil.

Now a busted mount may've allowed the hot post to short against a shroud or the block killing your spark.

re you very sure that what you say is true on his JD? Not just a general statement?

Mr. T. Minnesota · Mar 21, 2014

JMOR,
Started as a general statement and wondered why his JD did not run. Had checked on line and could not get a definitive answer and trust the Forum to give a straight up answer. Did not know about the Honda! Another reason for asking is I have used diodes on Wincharger generators and tractor generators and was told the housing of the diode had to be grounded.
Mr. T. Minnesota

gears · Mar 21, 2014

J Mor. You calling me out!?

JD lawn with cyl coil would be a kohler and that is how the coil is triggered in points ign.

Now, your powersports application uses a CDI which stands for Capacitive Discharge Ignition- a whole 'nother animal requiring the coil to be grounded (if you noticed, that atv coil only had one wire going to it - that comes off the CDI box which is sometimes called the ignitor, and in some cases is divided into 2 or 3 separate electrical components)

gears · Mar 21, 2014

oops, darn ipad and it's double send!

JMOR · Mar 21, 2014

(quoted from post at 20:12:51 03/21/14) JMOR,
Started as a general statement and wondered why his JD did not run. Had checked on line and could not get a definitive answer and trust the Forum to give a straight up answer. Did not know about the Honda! Another reason for asking is I have used diodes on Wincharger generators and tractor generators and was told the housing of the diode had to be grounded.
Mr. T. Minnesota

bout 99% of the time, the coil housing does not need to be grounded, even in 'most' Hondas, but there is always that rare oddball! Diodes: vast majority have case to cathode, but reverse are generally available. However, isolated case is not at all common, but have been available. So, grounding a diode case is a bit odd, unless the application/circuit has cathode or anode to ground.

souNdguy · Mar 21, 2014

yup. I got some big suckers the screw into an aluminum head sink and have a flexible braided pigtail on top.

JMOR · Mar 21, 2014

(quoted from post at 20:45:00 03/21/14) J Mor. You calling me out!?

JD lawn with cyl coil would be a kohler and that is how the coil is triggered in points ign.

Now, your powersports application uses a CDI which stands for Capacitive Discharge Ignition- a whole 'nother animal requiring the coil to be grounded (if you noticed, that atv coil only had one wire going to it - that comes off the CDI box which is sometimes called the ignitor, and in some cases is divided into 2 or 3 separate electrical components)

ah, just a small jab.........."and close the circuit firing the coil." Since all those conventional Kettering system fire when points OPEN, not when they close. But you knew that. :wink:

gears · Mar 22, 2014

I thought we were answering his question about whether or not a round coil needed grounded to work properly, not explaining the complete workings of a points style ignition. But good to state as many people think an open circuit is on......

And if you'd quoted my whole reply instead of omitting the 'open' part of "open and close to fire the coil" I wouldn't've felt the need to keep adding to this thread

JMOR · Mar 22, 2014

(quoted from post at 08:20:46 03/22/14) I thought we were answering his question about whether or not a round coil needed grounded to work properly, not explaining the complete workings of a points style ignition. But good to state as many people think an open circuit is on......

And if you'd quoted my whole reply instead of omitting the 'open' part of "open and close to fire the coil" I wouldn't've felt the need to keep adding to this thread

ow about "close and open to fire"?

TheOldHokie · Mar 22, 2014

(quoted from post at 08:20:46 03/22/14) I thought we were answering his question about whether or not a round coil needed grounded to work properly, not explaining the complete workings of a points style ignition. But good to state as many people think an open circuit is on......

And if you'd quoted my whole reply instead of omitting the 'open' part of "open and close to fire the coil" I wouldn't've felt the need to keep adding to this thread

Now, now - play nice and share your collective knowledge for the less well informed. Besides, you are both too old to bring any real firepower to a pi$$ing contest :lol: :lol: :lol:

TOH

Royse · Mar 22, 2014

Mr. T. I don't know what model JD you're working on, but my 200
series (210, 212, 214) have a single cylinder Kohler engine with
a cylindrical coil. On those, it does not have to be grounded.

I didn't have the right bracket to hold the coil for one of them,
so I used a slightly over sized bracket and wrapped the coil
in a strip of old inner tube to take up the slack. Now it's nice
and snug, but definitely not grounded. Runs fine.

If that's what you have I would check the points, and that silly
little pushrod they use to open the points. They've worked well
for years, but they do get worn. Also check the wire where it
comes out of the metal cover. I have had them chaff through
from vibration. Some people forget to put the grommet back in.

teddy52food · Mar 22, 2014

In order to complete a circuit the secondary wire would have to be grounded. Most are connected to one end of the primary so the coil case doesn't have to be grounded.

gears · Mar 22, 2014

Innit the 2ndary grounded at the plug's electrode right after the gap?

I'd thought this thread was closed, but it appears it's still open, just hope nobody get's short over it..... Or am I misconnected?

Royse · Mar 22, 2014

(quoted from post at 17:58:30 03/22/14) Innit the 2ndary grounded at the plug's electrode right after the gap?

I'd thought this thread was closed, but it appears it's still open, just hope nobody get's short over it..... Or am I misconnected?

Gears, I don't think it's closed. Mr. T. asked for suggestions and
he's getting them. As far as I know, he is still reading and going
to try some of the suggestions until he gets his machine fixed.

Posts sometimes get sidetracked, that's nothing to get short over.
Mr. T.'s been around here quite a while. I'm sure he'll get it fixed!

gears · Mar 23, 2014

Royse, it was a pun (albeit a bad one) on the types of circuit:
Open - pathway incomplete, no current flow = "off"
Closed - path complete, current flowing = "on"
Short - path interrupted, current 'leaking' or taking a shortcut = electrocution/shock/fire/damage; bad
Misconnected - components connected incorrectly (reverse polarity, completely wrong connector etc) = "off"

I get a little slap happy on the weekends

no reason for members to Disconnect from the thread

Royse · Mar 23, 2014

I must have been tired Gears, I missed the pun the first time.
Odd too, because I really like puns. By the way, they're all bad! LOL

12 volt cylindrical ignition coil

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