210 IH Swather Coil

This message is a reply to an archived post by LonM on August 07, 2010 at 19:30:20.
The original subject was "Re: 210 IH Swather Coil".

a coil running fine will not be hotter than the engine. Tells me that the running voltage 14 volts is too much for it. Can you put the old coil back on and test out the operating characteristics?

most times the starter power is full voltage while starting. When running the voltage goes to 14 volts. The coils with internal resistance has a resister that as it warms up increases the resistance to keep the coil in the proper voltage range. If this resister is not working properly the coil could be overheating and breaking down. The new coil could be faulty.

good luck
george

What you describe as a resistor that increases in ohms resistance value as it gets physically hotter I would call as a "Thermistor". Im NOT aware typical tractor coils have a built in thermistor but hey Im never too old to learn. (Maybe only Swathers use them???)

Some manufacturers used a piece of thermistor wire as the ballast on 12 volt tractors that used a 6 volt coil, that was so there would be a hotter spark for starting but once the thermistor warmed up and its resistance increased, it acted as a normal series voltage dropping (12 to 6) ballst resistor so the 6 volt coil only got 6 volts to avoid overheating

What many folks call an "internally ballasted" coil ACTUALLY DO NOTTTTTTTTTT HAVE ANY DISCRETE STAND ALONE RESISTOR TUCKED AWAY INSIDE THE CAN. Their primaty winding/coil has sufficient length and/or ohms per unit length such that they have a total primary winding in the 2.5 to 4 ohms range making them suitable for use on 12 volt tractors with no other series external ballast needed. They are labeled something like "12 volts" or "12 volts NOT for use with ballast resistor" but most DO NOT have any actual internal resistor. Yep some were made like that but I believe that was more for older autos in the twenties n thirties.

Very generally speaking, a coil should run warm but not so hot you cant lay your hand on it

Anyway I was not aware they made coils with internal thermistors so maybe we can all learn something here today if that be the case??? Of course Im more familair with tractor coils NOT Swathers so if you have any more tech info on that family of coils id appreciate it

Take care now, good info you posted

John T

George, with a POSSIBLE few exceptions, in the modern era, there's no such thing as a coil with a resistor built in, much less a PTC resistor.

A 12 Volt coil made to be used without an external resistor simply has more turns of wire in it's primary than a coil made to be used WITH an external resistor.

Yo Mayor Bob, Exactly what I was thinkin (We most always agree it seems) but gave him the benefit of the doubt in case IHC made some weird swather coil I wasnt aware of, Ive learned never say never the hard way at times grrrrrrrrrrr

Wayyyyyy back in the twenties n thirties some auto manufacturers produced coils with actual built in resistors and they often had a groove around the can where the little seperate compartment existed and held the resistor. But like you Ive NEVER seen such on a tractor coil in the 30's to 50's vintage although many folks call them "internal ballsted" or think theres a resistor hid inside there, usually NOTTTTTTT

I think early new gen Deeres (I think some Fords also) used some thermistor or heat compensating resistor or whatever you call it as a ballast so the coil voltage was greater at startup but I doubt swathers used that???

John T

If you look in the Standard Ignition catalog, for example, they sell two types of ballast resistors... the PTC type and the non-PTC type.

The PTC type is typically used when a "starting bypass" circuit is NOT used, and the non-PTC type is typically used in conjunction WITH a starting bypass circuit.

for all older distributor systems

the fact that he has a wire from the starting circuit would tell me that he has a external voltage control system.

The second wire the run engine source would come from a source with a resister/regulator of some kind.

I never have seen a 12 volt coil expected to produce a clean spark at around 8 volts when starting the engine and then running at 14 volts on the primary circuit when started. You also cannot have proper voltage to the plugs at start while keeping the running voltage in specs with 33 percent change of supply voltage.

You will see that the starting voltage to the plugs will have a voltage 33 percent lower than running. As everyone here understands that is very undesirable.

Is your coil a ptc type? Do you have a amp meter? If you do put 12 volts across the coil terminals. Check the amp flow and see if drops off after a minute or so. This would be expected. if it does not drop you had better put a resistor on the run wire.

the versatile that we have has a ballast resistor on the running supply wire. If you leave the starting circuit wire off it will not start.

George

There is another version of an ignition resistor. I have an IH275 Windrower with an AMC 232 engine. It uses a resistive wire in conjunction with the starter solenoid. There isn't a physically separate ignition resistor that you can see. The ignition resistor is the special wire used.

In this configuration, a resistive wire runs from the ignition switch to the (R) terminal of the solenoid. Another wire runs from the solenoid (R) terminal to the coil. During cranking, the starter supplies full battery to the coil. After starting and the ignition switch returns to the "run" position, the solenoid is released and the coil is supplied through the resistive wire from the ignition switch.

If the resistive wire is not available, a common ignition resistor could be installed between the ignition switch and the (R) terminal of the starter solenoid.

By the way, if anyone needs a good AMC 232 Engine for their Gremlin or other 275 windrower parts, let me know.
K-Mo

John

the copper wire in the primary coil windings warms up as current flows through. the resistance then rises. AS the new 12 volt coils primary winding has many coils of very thin wire a temperature change of 20 or thirty degrees will change the resistance of the wire in the primary circuit. This will correct for the changes in primary circuit voltage.

quote from how things work

Copper is the most widely used electrical conductor because it is inexpensive and second only to silver in electrical conduction. Although low, copper does provide some resistance to current that is passed through it. The baseline resistance for a copper wire is based on the cross-section of the wire and the length of the wire. The resistance to the current generates heat. Resistance is temperature dependent, so as the temperature of the copper conductor increases, so does the resistance.

please give one of your new coils an amp reading cold and the hot. The primary circuit in the coil you describe is the variable resistance needed for the change in primary voltage. No old ignition systems will ever work correctly without control on output coil voltage.



take care
George

second chance garage

The next component is the coil's primary winding. Inside the coil are two sets of wound wire, comprising of the primary and secondary windings. The primary windings carry battery voltage through and create a large magnetic field inside the coil (this is discussed thoroughly in the section on secondary windings). Although the coil's primary windings receive voltage from the ignition switch, they are actually turned on and off by the distributor's contact points.

The contact points are opened and closed by a cam on the distributor's main shaft. As it spins the cam's lobes move the actuator outward, disengaging the contacts. When the lobe passes, the contacts close, turning on the coil primary windings. The amount of time the points remain closed is referred to as dwell, and is an important factor in engine tuning.

Attached to the points is a condensor, an electrical device (capacitor) that limits current flow through the points to increase their life. The condensor is necessary because the points are opening and closing rapidly, and as they do so the voltage/current is interrupted. This causes an arc, or spark, between the contact points. Over time, this arcing will erode the material on the points and deposit carbon, and eventually the points will not pass current. The condensor acts as a current-absorber to limit the amount of arcing as the points open and close.

The next component is the ignition resistor. It is necessary because ignition coils are designed to step up battery voltage high enough - and fast enough - to keep the engine running at high rpm. That means that, as designed, the coil would produce too much high voltage at low rpm and heat up. Automakers long ago realized that there were two solutions to the problem: using two coils (one for low rpm and one for high) or an ignition resistor. Obviously, the resistor approach is the least expensive and most reliable, so that's what they did. The resistor used varies is resistance as a function of temperature, and limits the voltage to the coil accordingly. As the engine revs up the resistance lowers, allowing more voltage to the coil for fast running, and the reverse happens when the engine slows down. At idle, for instance, only about 7 volts is going through the coil primary windings.

The only time the resistor is out of the circuit is during startup, when the engine needs all the spark it can get. It's bypassed in the ignition switch's start position so that, during starting, the coil gets full battery voltage. Ignition resistors can take many forms, depending upon the manufacturer of the vehicle. Some builders mounted a big resistor on the firewall and some others utilized a special type of wire (resistance wire) running from the ignition switch to the coil. Still others used coils that were built with an internal resistor. None of these is any better an approach than the others, but it's important to know which type you have, and that you have one!