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Small Engines (Lawn Mowers, etc.)/Solo 643-IP chainsaw ignition module


QUESTION: Dear Mr. Jones,
  I have a Solo 643IP chainsaw that the ignition module failed.  This is an electronic ignition and factory part # is 2300837 and relatively expensive.  The module looks identical to a Stihl MS361 module and I replaced it with a MS361 aftermarket module.  The saw seems to run fine, however, the Solo specs state that the saw has "intelligent engine start and engine management" which implies that the ignition module must have more tasks than simply providing a spark and being a rev limiter.  The question I have is:  Does the MS361 aftermarket module have the same electronic capability as the OEM Solo module?  I don't know if there is a way to determine that.  In any case, I most likely will order a new OEM module to replace the aftermarket MS361 module just to be safe and to get the most performance out of this saw.  Thanks in advance. Dave

ANSWER: Most manufactures rarely provide that level of detail about the ignition module.

Many modern modules have a transistor or two inside, usually in a darlington pair configuration, for timing advance.

However, many modules are manufactured by just a few companies and I'm betting that most of them are very similar as it is probably cheaper to keep the tooling the same instead of changing the tooling for the various equipment manufactures.

Have you checked Ebay for a used Solo module?


---------- FOLLOW-UP ----------

QUESTION: I have checked ebay for a used module, unfortunately, there are not many parts available for Solo saws here in the US. I am now thinking of taking the OEM and the aftermarket (Chinese made) modules to work and trying to have them X-rayed (work has a couple of Xray machines that are used to look at the internal parts of memory chips).  I would bet that the OEM module has more components on the pcb than the aftermarket one. If I can get Xrays done, I will let you know the results.



An Xray would be pretty neat...we don't have one at our shop.

I suspect you are correct with respect to the Chinese module.

Years ago Phelon used to make almost all the 2 cycle engine coils.  These days there are very few markings on the modules so I'm not too sure who is making them.

Let me know if you get to Xray the modules.


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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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