Seeing the voltage change from 6V to 12V when the points open/close doesn’t make sense, it should stay constant. The voltage should be applied to the primary side of the coil and the points should be on the secondary side. Any opening/closing should affect the secondary side. You need constant voltage applied to the primary side to keep the magnetic field constant. When the contacts open the magnetic field builds up in the secondary, and when they close the field discharges to the plugs.<div><br></div><div>Also the points act as a switch. If you think about a wall switch that turns on your room lights, the voltage at the lights changes when you open or close the switch, it’s full or zero, but not half. </div><div><br></div><div>Carl<br><br>On Thursday, August 26, 2021, John Hall <<a href="mailto:jtchall@nc.rr.com">jtchall@nc.rr.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
No PO, we bought it new. Put a new harness on 20-25 years ago--its
in good condition and we haven't hacked into it anywhere.<br>
<br>
6 or 12 volts to the coil (depending on if the pts are open/closed)
except when cranking, then it maintains 12. It is my understanding
the starter solenoid is what provides the boost in Voltage when the
starter is engaged--I verified it is outputting 12 volts when
starter engaged and I had the wire disconnected from solenoid--this
is on the R terminal.<br>
<br>
The new coil is marked 12V, nothing else, yet the description on the
bill was for 6 volt. It was in an unopened CaseIh box. Part number
on the box and online manuals matches my 50 syear old paper parts
book--thats encouraging. Trying to cross over the CaseIH part # to
see exactly what it calls for doesn't really work too well, I kept
getting different answers, thats why I ordered one from the
dealer--not saying its right, but figured OEM would be the simplest.<br>
<br>
The old coil was probably on there for 15+ years--it only had one
wire to the + terminal. IH schematic shows 1 wire as well.<br>
<br>
I've looked for an external resistor and so far have found nothing.
Researching online suggests ignition systems using resistor wire--I
have no idea about such.<br>
<br>
I'm willing to go get a coil from the parts house or rob one off a
lawnmower for testing. I just need this thing fixed ASAP as I don't
have another tractor to do what it does--and my time needs to be
spent on other things. Bad how this stuff never happens in the off
season when time is on your side!! <br>
<br>
John Hall<br>
<br>
<br>
<div>On 8/26/2021 10:27 PM, Carl Szabelski
wrote:<br>
</div>
<blockquote type="cite">
If you’re reading 6V at the coil on a 12V system with the engine
off and the ignition switch in the on position, then you’re
dropping 6V from the starter relay to the coil. That would
indicate you have a ballasted ignition system which has a ballast
resistor in the wire going from the relay to the coil. There
should be a second wire attached to the + terminal of the coil
that provides 12V during a start by temporarily bypassing the
ballast resistor through the ignition switch when you start. The
reason the new coil is marked 6V is because that’s what you need.
The coil should only need 6V when the engine is running. Running
at 12V will cause the coil to overheat and eventually fail.
Applying 12V during a start for a short time doesn’t hurt it.
<div>
<div><br>
</div>
<div>If you don’t have the second wire, then you probably have a
coil with an internal resistor. That requires 12V to the coil
at all times, 6V will be dropped internally through the
internal resistor. Maybe the PO did some rewiring and left a
ballast resistor in while putting in a coil with an internal
resistor. If you do have an in-line ballast resistor and a
coil with an internal resistor, then you have too much
resistance and you’re dropping too much current going through
the coil, which gives you a weaker spark. That may be why
putting 12V directly to the coil makes it run better. You’re
overcoming the extra resistance with twice the voltage.</div>
<div><br>
</div>
<div>The first thing you need to do is determine which type of
system you have (ballasted or non-ballasted), and if you have
the right coil (internal resistor or not). From looking at the
wiring diagram I sent earlier it doesn’t seem to indicate you
should have a ballasted system since it doesn’t show a second
wire at the coil. But again, maybe the PO made some
modifications?</div>
<div><br>
</div>
<div>Now if you’re dropping 6V at the starter relay, then the
relay or the connection to the relay is suspect. That’s why I
suggested testing the starter relay to see if you were
dropping voltage there.</div>
<div><br>
</div>
<div>Once you have a definite idea of what type of system you
have, it should make finding the problem easier.</div>
<div><br>
</div>
<div>Carl<br>
<div><br>
On Thursday, August 26, 2021, John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div> points, plugs, cap, rotor and coil are all new. I
verified with my 50 year old parts book and it has the
same part# for coil as what online parts at Case is
showing. The new coil has 12V on the outside, but the
bill had 6V. Box was sealed up, but it came from
overseas, so a lot of variables there<br>
<br>
Point gap was verified when I had the distributor off
and plate out so I could make sure weights were free and
springs not broken.<br>
<br>
I had my voltage regulator with me yesterday. When I
tried to check at coil with engine running rough, it
showed OL for whatever reason. I've checked so much
stuff lately that I'm not sure but I think I got 6 and
12 volt readings depending on where the points were once
I shut the engine off. I tried checking the voltage with
engine running at the fuel solenoid for reference and it
was floating all over the place from 4 to 13.5V. This
was observed with the engine hot and running rough. With
engine not running it holds steady a little over 12. <br>
<br>
Last night I also found that the wire to the coil and
the wire to the R terminal on starter solenoid can read
6V (little less actually) while the wire going to the
fuel solenoid in the carb was reading 12V.<br>
<br>
John Hall<br>
<br>
<br>
<br>
<div>On 8/26/2021 6:35 PM, Howard Pletcher wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">It's not
unheard of, particularly since many of those parts
now come from overseas. To me, swapping with
another if you can find something to swap with
would be the easiest way to prove or eliminate
that as a possibility. </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Make sure
your points setting is close to spec and they are
clean as that would affect the ignition. Have you
looked at your plugs, not thinking that's the
problem, but if they are fouled or badly gapped,
they could have an effect. You also might run it
until it heats up and needs the 12V to see if it
still shows 6V to the coil. If not, then it's
somewhere else in the circuit.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Many of the
other things suggested have no connection with the
ignition circuit. </div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, Aug 26,
2021 at 5:12 PM John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div> Howard, you are leaning toward new coil and
old coil are both bad?<br>
<br>
John Hall<br>
<br>
<div>On 8/26/2021 3:47 PM, Howard Pletcher
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">No,
what he is reporting is just what should
be happening. With the points open, no
current is flowing through the primary
circuit and there is 12V at the + side
of the coil. When he bumped the starter
and closed the points, the current
flowing through the resistor in the
primary circuit results in a voltage
drop so that there is now 6V on the coil
as intended. </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">The
wire from the starter to the coil does
send 12V directly to the coil, but this
is only engaged while the starter is
cranking in order to produce a hotter
spark for starting and is not connected
to 12V the rest of the time.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">The
fact the coil seems to require 12V to
its terminal when hot points to an
internal problem in the coil as
discussed by Dell in the Yesterday's
Tractors article.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Howard</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu,
Aug 26, 2021 at 2:53 PM Carl Szabelski
<<a href="mailto:c.s.szabelski@gmail.com" target="_blank">c.s.szabelski@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> By
the way, I believe it’s not the coil and
is related to the cranking motor.
Especially since the voltage drops when
you bump it like you said. Something in
the motor may be partially shorted or
corroded, causing a voltage drop to the
coil. The coil should always see 12V
whether or not there is a resistor,
internal or external. The resistor is
essentially after the coil winding and
drops the voltage after the winding, not
before it. If the engine is running fine
when you directly connect 12V to the
coil, the coil is working like it should
and is good.
<div><br>
</div>
<div>Carl<br>
<br>
<br>
</div>
</blockquote>
</div>
</div>
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