140 original 12 volt with generator

Farmall Super A, AV, 100, 130, & 140 1939 - 1973
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140 original 12 volt with generator

Postby Senaham » Thu Aug 26, 2021 9:11 pm

Recently acquired a running mid 1960s 140 with attachments as part of a property purchase. I did not have the heart to kick the tractor out of it's home. Still getting use to it, but cutting the grass on the property with the Woods finish mower has been a ball. Wiring was frayed in spots and the light switch was inoperable, but the key start would fire it up every time. Started having issues after long periods of running, stalling under load, misfires and shutdowns. On detailed inspection most wiring connections at the voltage regulator were hanging on by a thread, the ballast resistor was cracked and the battery was not receiving a charged. A rewiring was in order. A simple task.....

Simple if I had taken a picture of the wiring hookup on the ignition switch and ammeter prior to disconnecting them! Overconfidence and the inability to located a decent, detailed wiring diagram has my beautiful rewiring work failing to produce a spark. It's something simple, which is really what bugs me. I have completely bypassed the light switch as this needs to be replaced. The wiring for the lights was run, but left unhooked. Voltage regulator contacts cleaned adjusted and polarized. Starter motor cranks strong when I turn the key, but no ignition. Starter and negative side of ignition coil with inline ballast are connected to these identified terminals on the ignition switch. Jumper from an ammeter terminal is providing the battery power to the battery terminal of the ignition switch.

Tracing the issue with my voltmeter tomorrow, but curious on others thoughts as to where I screwed up. Could not identify by sight the polarity of the ammeter terminals, so I may have wired this backwards. No ballast resistor is shown on the wiring diagram I have for a 140. I put one in as the original owner had one wired in. Could this be my issue?

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Re: 140 original 12 volt with generator

Postby tst » Thu Aug 26, 2021 9:24 pm

yes it had no ballast from the factory, test the wire to the coil for battery voltage ? ballast is only needed if your coil has no internal resistor

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Re: 140 original 12 volt with generator

Postby Gary Dotson » Fri Aug 27, 2021 6:05 pm

Disconnect the low voltage leads from your coil and measure the resistance across the two coil posts, 1 1/2 ohm, give or take, it needs a ballast resister, 3.0 ohm, give or take, no resister needed.

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Re: 140 original 12 volt with generator

Postby inairam » Fri Aug 27, 2021 6:48 pm

if you decide to replace the wiring brillman has an excellent harness https://brillman.com/wire-harnesses/?fw ... eering-140
When you only have 9 horsepower you need to know the names of all of the ponies!

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Re: 140 original 12 volt with generator

Postby Senaham » Fri Aug 27, 2021 8:09 pm

Thanks to all! tst nailed it. I removed the ballast and she fired right up. New wiring, a little voltage regulator maintenance and tightening a loose fan belt has done wonders. She now cranks with authority and the battery is getting charged. Lights are next. The fronts are still on the tractor. Hopefully I can rebuild these and get them to shine bright again. The rear lights and flasher are unfortunately long gone.

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