Field Resistance Coil

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Field Resistance Coil

Postby ScottyG » Sun Jul 18, 2004 8:08 pm

Hi Everyone. This is my first time on the Farmall Cub message board and I'd like to formally introduce myself. My name is Scott and I'm the proud owner of a 1948 Cub. I bought it and its IH C3 60" mower deck from a co-worker back in May. It had sat for several years from an apparent ignition problem where the previous owner had "given up the ghost." After my friend and I trailered it to his shop, monkeyed with the contacts and put some decent gas in it, he fired right up. Compression in each cylinder is a cool 112 psi. I even drove it home from 6 miles away. Not bad for what had been described to me as a basket case.

A week later, I had it stripped down to the tranny and have been spending most nights after work sand blasting every portable part. I'm waiting for some more international red paint to come in and then I can honestly say I'm on the eve of putting everything back together. I feel like a kid at Christmas!!

Ok now for the questions. I have two that I think are relatively simple. The first involves the light switch. There are two field coils. One controls the dim on the headlights and the other is a generator field resistance coil that controls the charging output. Can this resistance coil be re-made? I can faithfully wind a new coil but the original one had some kind of insulator inside that I've never seen before. If you touch it with your fingers, it has the consistency of formica. Does anyone know of the equivalent resistor and resistor type (wattage, etc) that I could use in place of the coil?

Second question. In the decal package that you buy for the 1948, there is a sticker that says "open" with a little arrow around it. Where does this go?


I've gone on long enough. Thanks for this great site and I look forward to being part of the great hobby that is cubs!

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Postby Wireharness » Sun Jul 18, 2004 8:25 pm

If you contact maloybig@msn.com

He has the original resestors for the head light switch also can help you out on other wiring information.
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Postby John *.?-!.* cub owner » Sun Jul 18, 2004 8:58 pm

The cutout also has a field resister bult into it. You can run a jumper from the F term of the generator to the F term of the cutout to provide the electrical equivalent of the one in the light switch, and still let the light switch apply the ground for full charge. Nobody will know the difference unless they take the hood off. My 49 (Missy) is wired that way due to a bad resister.
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Postby Jim Becker » Sun Jul 18, 2004 9:12 pm

What John said will work fine, assuming you are asking about the field resistor. It is Delco 1878070, 2.8 ohms and needs to be able to handle something around 12-15 watts. The dimmer coil, Delco 814545, is 5 ohms, probably needs to handle more wattage than the other.

The "OPEN" decal does not belong on a Cub. By the way, a '48 model should have hood sheet decals that say "McCormick-Deering Farmall Cub" and does not use the circle Cub decal.
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Field Resistance Coil Response

Postby ScottyG » Mon Jul 19, 2004 9:07 pm

Thanks for the great tips guys but, me being a novice with the Farmall electrical system at the moment I hope you don't mind a followup ignorant question.

John, if I'm looking at the back of the light switch with the cutout on the bottom right, the original wire configuration had the generator field resistance coil wired from the ground post (on the bottom left) to one of the two legs on the cutout. From the other leg on the cutout, a wire went to the left hand lead on my voltage regulator. (I have the three lead black box type on top of the magneto with a cylindrical IH coil next to it) The middle contact on the voltage regulator is connected to the negative side of my ammeter. If I'm following you right, do I then wire the generator directly to the cutout? Sorry for my confusion on this.

Also, the original wiring had another in-line fuse wired from the bottom of the built in light switch fuse leg to the #2 screw. What was this for?

Thanks!!
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Postby ScottyG » Mon Jul 19, 2004 9:37 pm

Well, I think I'm starting to answer my own questions with this but I'm still looking for some confirmation. It looks as through my '48 was originally magneto ignition. For whatever reason, the old coil and condenser were abandoned for a newer coil and condenser mounted next to a new 3 lead voltage regulator on top of the magneto. Consequently, the cut out, field resistance coil, etc. that are on the lightswitch aren't used anymore and the switch was re-wired. Does this make sense to everyone? Anyway, I'm making my discovery based on following a link the the ATIS.net site and reviewing the electrial diagrams. I see remnants of my system in both the old and new drawings. Looking at the newer one it appears that the lightswitch fuse isn't used anymore? I think maybe I'll just wire my system up to the newer drawing and see what happens. I'm sure everyone will be hearing from me if I fry everything!
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Postby Rudi » Tue Jul 20, 2004 1:32 am

Scotty:

Consider re-wiring according to the original for your production year. My Ellie-Mae was a mess and I have re-wired it as per the 48 specs. Granny my 47, has been converted to 12 volt, and it is a real mess. She is getting a re-wire as well back to 47 specs. Both have/will have mags.

With the original configuration, the tractor is really reliable and easy to maintain and troubleshoot as needed.

Yust me dos centavos, for whatever that is worth :roll: :D
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Postby ScottyG » Tue Jul 20, 2004 6:27 am

Rudi,

How would I know what the original wiring specs were for the '48? Is there some guidance or schematic on this somewhere? It looks as though the original ignition had a built in coil (still in place) and a condenser (missing) with a coil cap that held everything down. Also, the rotor was replaced sometime with one that is much larger than the original shown in the parts catalog for that model year. No original voltage regulator either so I'm assuming that that's what the cutout was for on the light switch.

As previously stated in my thread, the new ignition is wired with a voltage regulator that's basically a 3 lead black box mounted on top of the generator. A newer cylindrical coil and condensor is mounted next to that near the magneto. The old coil has been completely disconnected and a wire was added from the points to the newer coil.

If you follow the newer schematic on the ATIS.net site, it doesn't look like you can get the lightswitch to adjust the generator output between low and high. I was going to use John's suggestion and make a connection between the generator F term to the cutout on the lightswitch. Will this get me where I'm going? Once I wire the cub back up and get it to run, I was planning to eventually restore the old ignition to where it should be. At this point though, I'll be happy to just get it to run :)

Thanks!!
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Postby Rudi » Tue Jul 20, 2004 10:14 am

Scotty:

How would I know what the original wiring specs were for the '48? Is there some guidance or schematic on this somewhere?


I am no genius on wiring, but I have used the wiring diagrams in the GSS-1411 in conjunction with the wiring diagrams on the ATIS site. That helped a lot. The GSS-1411 can be found on the Manual Server at the link below and under the Blue Ribbon Manuals link.

It looks as though the original ignition had a built in coil (still in place) and a condenser (missing) with a coil cap that held everything down.


You are correct on that one. The mag originally had a built-in coil, and condenser with the points in behind the rotor. Most PO's when the coil went, just put an aftermarket or whatever coil they had as an external coil and keeping the points and condenser where it is. Some even had the condenser on the outsitde as my 48 did.

You are in luck though. :) There are a few people on this board - DONNY comes to mind real fast who can help you rebuild your internal coil. Just ask em, and I am sure you will get lots of help.

Also, the rotor was replaced sometime with one that is much larger than the original shown in the parts catalog for that model year.


Easily fixed. Your CaseIH dealer, or Case Parts On-Line and I think NAPA has the correct rotor.

No original voltage regulator either so I'm assuming that that's what the cutout was for on the light switch.


47's and 48's did not have a regulator, but a cutout instead. You will find this usually mounted atop the generator. Cutouts have 3 terminals and Regulators have 4. Jim, did I get that correct??

As previously stated in my thread, the new ignition is wired with a voltage regulator that's basically a 3 lead black box mounted on top of the generator. A newer cylindrical coil and condensor is mounted next to that near the magneto. The old coil has been completely disconnected and a wire was added from the points to the newer coil.


Standard procedure and very easy to correct. Replace the condenser and insert into the mag under the rotor head along with a new set of points. (good to do this anyways) Make sure the gap is correct according to the manual. As for the coil - above comment still applies. Also, new coils are available right from CaseIH, but do not whatever you do, throw out the old internal coil. Guys like Donny can rebuild it again and someone in dire need of an internal coil will then have access to a rebuilt.

As for the last question, well I somehow managed to fumble my way through and have it connected correctly. I now have both charging positions and both dim and bright lights... just have to replace the 1129's with the proper 1133's.

Do as Jim Becker suggested first. He walked me through my problems, and he can walk you through yours. If all else fails, then go with the next suggestion. Try to keep it original if you can.
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Postby ScottyG » Tue Jul 20, 2004 1:25 pm

You guys are awesome. Thanks!!!!!!
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