Troubleshooting Dyna Ignition ???

The problem is no spark on a 1976 R75/6 that is modified for dual plugs with a Dyna ignition system and has been sitting for a while.

Here is what I found:

The pickup has a red and a white wire that run to the module:
Red wire has 8.9VDC with the key on and 8.0VDC while cranking
White wire changes from approx 1.4VDC to .8VDC while cranking

The coils:
Labled 1.5 ohms but each measures 2.8 ohms individually.
Green wire that looks like it comes from the original harness has 10.6VDC and is hooked to coil one and is jumpered to a red wire going to the module. Powered when the key is turned on.
Black wire from coil one to coil two has 6.25VDC at coil one and 6.0VDC at coil two.
Brown wire from coil two going to the module changes from 1.4VDC to 10VDC when cranking.

Module:
Also has a black wire going to ground that I verified to have no voltage drop when compared to the battery ground, and to show good continuity.

Battery:
12.2VDC

SO...it looks to me as though the pickup is changing state and sending a signal to the module. Then it seems as though the module is controlling the grounding of the coils by controlling the Brown wire. But I am wondering if the 1.4VDC that I measure as the low on the Brown wire is indicating that the module is not providing a good ground. Or is the pickup not changing state correctly...even though the module seems to change state?

Please let me know if it is obvious why there is no spark, or if there is a test I can do to determine which part is bad...

Dyna ignition

I have 2, Dyna III's still in the box, never installed. In the instructions, there is a line that says it's important to use a ventilated front cover because condensation can ruin the printed circuit board. Unfortunately, no instructions on what to do if it fails. If the bike has been sitting, it may have gotten moist. I don't understand how they work in great detail, but the condensation warning convinced me to not install the system on my bikes.

I installed a Dyna ignition on my old R75/7, still running strong after many tens of thousands of miles and several years when I sold the bike.

It should be noted however that I rode that bike year-round so it never had many of the afflictions that less frequently used airheads seem to suffer.

Steve

Well...thanks for the comments but I'm still

There is a ground on mine that grounds to the condensor. I've lost spark twice over the 15 years or so, and both times replacing the condensor cured the problem. It has been speculated that it was not the condensor, but the removal and replacement of the screw holding the condensor and ground wire, re-establishing a good ground that cured the problem. Good luck, HTH

Another sidetracked thread...

Remarkable how easy it is to go off on a tangent.

Did the bike run in your possesion? How long was it sitting around, going to assume you have done all the small things like make sure it is in neutral and the kill switch is "on"? (not trying to be smart-ass here, I've recieved more than one phone call from paniced buddies who had either left the sidestand down or hit the kill switch)

There is always the option of going back to stock configuration and making sure it runs at all....

Steve
With dissassembled R75/6 in garage

sgborgstrom...

Seems like any of those things would kill the Green wire which is switched on/off by the key. I don't remember for sure that the bike is in nuetral (light on), but it did crank without the clutch in and didn't move. I'm out on the road working in OR right now, but I can try cranking it with the clutch pulled in...just didn't think that a bike built in '76 would have that kind of lawyer safety switch.

When I'm back in town I'll try grounding and ungrounding the brown wire from the coils...that should simulate the points action and make a spark when it becomes ungrounded.

Otherwise... ...I guess nobody ever has a problem with Dyna ignitions.

Re: sgborgstrom...

[I guess nobody ever has a problem with Dyna ignitions.

Well, in truth, in more than twenty years, no problems. Once I thought I had a problem with the Dyna 3, but it turned out to be an intermetent fault in one of the coils.

Mac

oops

I just remembered, I may have my Dyna III installiations in my garage. I'm at work now....will have to check tomorrow if you want to wait...

Mac

Tom...any more info would be great. Post what you find in the installation instructions. I'm hoping that they also included some troubleshooting steps.
Thanks

Solved...

It ended up that one of the coils is bad, and since they are in series, or daisy chained, that caused both coils to not fire. The simple ohm test I did on the primary winding of the coil showed that the primary winding could flow current. But testing a coil like that does not guarantee that it will produce a spark.

Here's how I figured it out...it you care:

First, I removed the brown wire from the second coil that ran to the module and replaced it with a piece of wire that I could touch to ground. I alternatly touched it to ground briefly and then held it in the air. This simulated the action of a set of points or the module. Grounding the wire allows current to flow through the primary windings, just as when the points are closed. Holding it in the air stops the flow of current like when the points open. When the current stops flowing, the magnetic field that was created colapses and induces a current in the secondary windings creating the spark. Since no spark was created I knew that one of the coils was bad. So I unhooked the black wire that joins the first coil to the second and attached my test wire to the first coil. This created a spark when I alternatly grounded and then held it in the air.

This shows the down side of joining two coils in series to create a dual plug system. Only on coils needs to fail to stop the engine.

To create a better dual plug system you would need two pickups (or points) and two modules to run the coils independently.

Hope this helps