Farmall B - Light dimmer coil

Dave H (MI) · May 26, 2008

Hi all! The used lights I bought on ebay are working just fine. Very minor cleaning was all the switch needed to fire them right up. Haven't done the rear light yet as I am short a 12v bulb for it. Only problem I am having is the dimmer resistance coil is overheating. I have both bright and dime lights working as we speak but the switch has an odd loop of wire that somehow provides for light dimming and it is smoking slightly and the insulation on it is charring. How come?
Is there maybe a more modern version that could replace it? I would like to keep the bright and dim lights working. Thanks and happy MD!

Joe Kimbriel · May 26, 2008

I think that resistor was for a 6 volt system.

Bob · May 26, 2008

A dimming resistor works by converting excess electrical energy to heat.

Dimmer resistors simply get HOT. Always have, always will!

I can see there MAY be an issue depending upon the wattage draw of the 12-Volt lamps vs. the original 6-Volt lamps, however those resistors ALWAYS did get hot. They are wrapped in an asbestos or other fiber wrap, which should NOT be burning off, no matter what. HOWEVER, there may by oily residue on there, from your fingers, etc, that IS smoking as it burns off.

Dave H (MI) · May 26, 2008

I think that covered it guys, thanks! It was and is getting quite hot and I suspect the smoke was from dust accumulated on it. Decided that I really have no use for it if it is going to burn so I turned on the dim lights and let it smoke until it stopped. Lights still work and we are now smokeless.

ScottyHOMeY · May 26, 2008

I'm chucklin' here, Dave. I'm chimin' in late, but it sounds like you guys got it sorted out.

Same thing when I first fired up my BN after the rebuild. Smoke just bailin' out of the switch box. Great, sez I. Got her all painted and runnin' and now I'm gonna burn her up. In mine, I think it was the resistor in the charge circuit as she only smoked on L. It all cleared up once I'd scorched a lot of years of grime and dust off of it.

Dave H (MI) · May 26, 2008

Hi Scotty! Yeah, that little curly-cue of wire that passes for a resistor was sending off little puffs of smoke and looking like it might just catch fire but as soon as it cleaned itself up it stopped (could still light your smokes on it if you cared too). Lights look real nice on there, especially cause they aren't new so they match well. Just kicking myself cause I did not order three 12v light bulbs so I have to wait for the mailman this week to bring me another. Oh well...I need a couple seat covers too! Going for a night ride tonight before the storms hit.
Later...

charles todd · May 27, 2008

I do not know what bulbs your tractor uses, but I am sure NAPA has them. I rewired my F504D and installed a new light switch (just an open coil, no insulation) and rebuilt my lights. The bulbs were sealed beams, GE 4411 and 4419 (can't remember but I think the small worklight was the 4419). They were less than $25-$30 for all 3.

Charles

Farmall B - Light dimmer coil

Dave H (MI)

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Joe Kimbriel

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Bob

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Dave H (MI)

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ScottyHOMeY

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Dave H (MI)

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charles todd

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