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FREEDGUY 
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Joined: 15 Apr 2017
Location: South West Mich
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 Topic: EXTERNAL RESISTOR IGNITION ??
Posted: 24 Mar 2018 at 6:55pm |
Could someone tell me how/where the resistors are located on a '69 180? Dad and I were attempting to do some ignition maintenance on the tractor by first,replacing the (pretty confident) original key switch. Since "we" have owned this tractor,8 years, have only seen a ceramic block looking gizzmo on left/hand side of engine below fuel tank and directly forward of PTO lever(hydraulic). It has 1 wire that comes from the IGN switch to 1 end and another wire that goes to the + side of coil. We have always seen a wire "close" to that general area that was capped off with a wire nut that we never gave much thought about until today. We traced that wire back to ANOTHER ceramic block on the R/H side of engine close to the starter. This block has "most" of the wires that match the wiring chart in the manual( 1 of the wires needs to go to a terminal off of the starting solenoid) but is missing the IGN portion that would go to the coil. When the "block" on L/H side is tested for voltage, the input side has 13.4 volts but the other side only has 7 which goes to the coil? BTW, the block on the left has spade connectors,the block on the right has screws with forked connectors. The coil on the tractor clearly says that an external resistor is required. We are at a loss to know which/what resistor is correct. Sorry for the long post but thanks to any that reply  |
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DougS
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Location: Iowa
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Posted: 24 Mar 2018 at 7:46pm |
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Try opening and closing the points manually. Read that output voltage where you had 7 volts. If it switches between 7 and 14 volts as you open/close the points, thats the ballast resistor.
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Gerald J.
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Joined: 12 Sep 2009
Location: Hamilton Co, IA
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Posted: 24 Mar 2018 at 7:58pm |
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Sounds like that resistor on the left side is the ballast resistor for the 6 volt coil on the 12 volt system. The other one might have some other purpose. On my gas 4020 of the same age, there is a ballast resistor and a special contact on the starter solenoid that applies nearly full battery voltage to the coil while the starter has pulled the battery voltage down for better starting. The other resistor might be there for a similar purpose on your tractor.
Originally in the 4020 the ballast resistor was in the ignition switch some years and a resistor wire some years. Mine had been reworked poorly and gave up while I had hay on the ground so I had to jump direct to the added ceramic ballast resistor to finish haying. I've reworked the wiring to make it not do that again. One of the important things I did was to take all the Scotch Taps out that were going open.
Gerald J.
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FREEDGUY
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Location: South West Mich
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Posted: 24 Mar 2018 at 8:02pm |
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Doug,thanks for the reply, but I looked up the ignition portion of our machine on AGCO PARTS and took that # and googled to find that what is ailing our machine is the "block" on left side ahead of PTO lever. WTH is the "block" on R/H side behind starter?? That I could NOT find in the parts book. We read the voltage off of the ceramic "block's" input/output side,12 in/6 out,never got into the distributor. Thank you for the reply!!
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FREEDGUY
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Posted: 24 Mar 2018 at 8:19pm |
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Gerald, you are without a doubt onto something,but to a local mechanic that looked at it today, he had no idea why the volts dropped by 1/2 from 1 side of the block to the other, we haven't had a 6 volt ALLIS on the farm since the WD,LOL !!
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Gerald J.
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Location: Hamilton Co, IA
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Posted: 25 Mar 2018 at 10:51am |
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But 6 volt coils on a 12 volt system need that ballast resistor. Otherwise they will burn up from excess current. Some 6 volt hot rods used 3 volt coils with ballast resistors because the resistor and coil combination allows for a faster rise of coil current when the points are closed and so the single coil can run a V-8 at 7000 RPM and faster. Not a need on the tractor but I'm guessing with the 6 volt coil on your tractor that the second ballast resistor gets hooked in parallel with the run ballast resistor to improve spark while the starter is pulling the battery voltage down. On my gas 4020 the low voltage coil is give full battery voltage while cranking.
The rate of current rise is limited by the coil primary inductance and its likely four times greater for a 12 volt coil than a 6 volt coil because of twice the turns to set the DC resistance of the coil primary that is the ultimate current limiter.
Gerald J.
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steve(ill)
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Posted: 25 Mar 2018 at 2:09pm |
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I would throw away both resistor blocks and get a new coil setup for a 12v system WITHOUT an external resistor needed.
Edited by steve(ill) - 25 Mar 2018 at 2:11pm
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Like them all, but love the "B"s.
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WF owner
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Location: Bombay NY
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Posted: 25 Mar 2018 at 4:03pm |
 steve(ill) wrote:
I would throw away both resistor blocks and get a new coil setup for a 12v system WITHOUT an external resistor needed.
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That was my thought, too. Why would you need a resistor on a tractor that was a 6 cylinder, 12 volt system from the factory?
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jaybmiller
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Joined: 12 Sep 2009
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Posted: 25 Mar 2018 at 4:36pm |
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The resistor is used to control CURRENT to not burn out the points.
I''ve never sawed a '12 volt coil' apart to see if it's really a 6volter WITH an internal 'ballast resistor' or if it's really a 12 volt coil of wire, others may know.
The 'points' will badly fail if you run more than 4 amps through them.
There's a few ways to go with this 'points-coil' ignition system aka Kettering(sp). Saty with OEM system, go 12 volt only, etc. They all will work fine IF properly maintained.
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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FREEDGUY
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Posted: 25 Mar 2018 at 4:58pm |
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Gerald, our coil says #703, 12 volt,external resistor required. I am ALL for dumping that "block" but what is the other gizzmo on the R/H side close to the starter?
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FREEDGUY
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Posted: 25 Mar 2018 at 5:08pm |
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I was under the impression that this resistor was to "UP" the voltage at start-up to aid in starting??
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jaybmiller
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Posted: 25 Mar 2018 at 5:54pm |
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Ok, I don't have a 180 wiring, have a 175 which may be close enough..
The original wiring, from the diagram, has a 4 post starter solenoid, that 'shorts out' or 'bypasses' the ballast resistor ONLY during starting. This does give the coil more power, so more spark...ONLY during starting...... My 67 Mustangs did the same thing...
Any way, some time during the tractor's life the original ballast resistor ( on the right side..with several wires..) burned out and someone 'bodged' the new ballast resistor ,located on the left side. The voltages you reported are 'nominal' or fine.
Now to be 'factory correct' the RIGHT ballast resistor should be replaced, and the left one removed. You'll have to rewire them a bit, back to 'factory configuration'.
Since the voltages are correct, I'll assume the tractor does start and run, so you could leave well enough alone
OR..
you could rewire to factory specs
OR..
you could buy a 'real' 12 volt coil( no external resistor required) and remove the existing coil and the left ballast resistor, with winor rewiring..
What you do is , well,.. up to you. It's YOUR tractor.
Those ceramic resistors are prone to failure as they have to get rid of about 24 watts of power, have to live out in the cold and heat..poor things. You can get 15 to 20 years from some of them. One alternative is to buy ones made by Dale, totaly sealed in a nice gold aluminum case,available in 50 or 100 Watt styles, and less than $10. While NOT 'OEM' ,probably outlive you, your kids, and gran kids too.
Hopefully this make sense out of the 'wiring' for you.
Jay
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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FREEDGUY
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Posted: 25 Mar 2018 at 6:11pm |
This makes PERFECT sense and THANK YOU for the detailed scenario!! We have no idea what this tractor has been through(pretty sure it has been laid over though),but "most" of the original wires match up with the OPERATING MANUALS wiring schematic. A new ,NON-RESISTORED coil will be coming soon. THANKS TO ALL that replied,maybe I can sleep tonight 
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FREEDGUY
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Posted: 26 Mar 2018 at 6:03am |
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jbmiller, are you saying that the output side of the current resistor should be the 6 volts to a 12 volt coil ? I pondered that for awhile last night and yes, the tractor runs sweet "once" it starts; been starting harder as time goes by.
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DougS
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Posted: 26 Mar 2018 at 6:50am |
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The output side of the ballast resistor should be about 6 volts into a 6 volt coil - with the points closed. With the points open the output of the resistor will be about 12 volts. Assuming a 12 volt system. Once the tractor is running you won't be able to measure the resistor output side. The output voltage will be pulsing. With a scenario as described by jaybmiller, you should be measuring 12 volts while the tractor is cranking - though it may well be considerably less as the starter will be drawing the battery voltage down. Also, this voltage will be pulsing as the points open and close. It's possible that the ballast bypass contacts in the solenoid could be bad, but describing how to troubleshoot that would be difficult to explain here.
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FREEDGUY
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Posted: 26 Mar 2018 at 7:07am |
Thanks Doug. The coil on tractor has a #703, says 12 volts and requires an external resistor. I could not find a manufacturers name though. The volt reading was taken at the ign side of resistor(12.2) and out put side to the coil (6.7). Tractor was only cranking during testing. Thanks again
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jaybmiller
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Posted: 26 Mar 2018 at 8:15am |
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A '12 volt' coil that requires a ballast resistor IS a 6 volt coil... The ballast resistor is typically 1.5 ohms, so... 1.5 ohms x 4 amps = 6 volts. The ballast resistor 'drops' or 'uses up' 6 volts... ie 12 volt battery - 6 volt 'used' by resistor = 6 volts to coil.
The confusion begins with the possible combinations 'out there'
6 volt battery 6 volt coil
12 volt battery, 6 volt coil, ballast resistor
12 volt battery, 12 volt coil(ext r rqd), ballast resistor
12 volt battery, 12 volt coil ,no resistor required
there's probably more but these are the common ones....
the numbers you give, tell me it's OK....about 6 volts across resistor..
6 / 1.5 is 4, so abut 4 amps of current to coil and points.
Jay
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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DougS
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Posted: 26 Mar 2018 at 9:28am |
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There are a lot of those “12 volt, needs resistor” coils out there. Yes, they are really 6 volt coils. At the time when autos and tractors switched over to 12 volts there were a lot of 6 volt coils in production, so they merely relabled them. When I look at a coil with an internal resistor I wonder how they can stuff a resistor of sufficient wattage inside. A true 12 volt coil should be designed as 12 volts due to winding and wire sizes.
Edited by DougS - 26 Mar 2018 at 9:28am
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FREEDGUY
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Posted: 26 Mar 2018 at 7:29pm |
A HEART FELT shout-out of thanks to both Doug and JB !! Your patients with our ailment and my dumb questions means alot  !! One or both of you were SPOT-ON pertaining to a previous owner "cobbling" the system, that is EXACTLY what happened  !! Dad has since been able to "put back" (as best as can be) the ignition system per YOU GUYS input!! I must admit, the 12 volt coil, 12/6 volt resistor really threw us for a loop  ! Without YOU guys (and others), I have a BAD feeling that this vintage of ORANGE will end up in/on a scrap yard, pertaining to "electric ignition". The diesel engines are a different story LOL! Again thanks to all, JEFF |
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DougS
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Posted: 26 Mar 2018 at 8:27pm |
Personally I'd scrap the 6 volt coil; bypass the ballast resistor; install one of those 40KV Pertronix coils. Fire it with a Pertronix EI system.
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FREEDGUY
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Posted: 26 Mar 2018 at 8:59pm |
I am awaiting a quote from the custom circuit man as I type, LOL! 
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DougS
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Posted: 27 Mar 2018 at 5:55am |
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Contact the Steve guy from here. He'll fix you up with what you need. Everything from the EI to the coil to the plug wires. Don't overlook the distributor cap. When your system is developing twice the usual voltage you don't want any weak links.
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