Darn Coil again (I think)

hrdman2luv

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Multiple module failures within a short period of time, raises the possibility that you are getting battery voltage to the module, at least intermittently, which could mean a short in the wiring, possible key switch problem that is being caused by vibration and bouncing.

Look at the side of the module where the ground wire attaches, and see if the epoxy is cracked, and you even be able to pick up a burnt wire smell if you put your nose close to it.

I think you're onto something about the key switch. That's about the only other source of electricity that could be getting the kill switch. Except when you consider that I don't get any spark when the kill switch isn't connected either...

BTW, it started yesterday for about 2 stokes. Most of the time, it fires for one stroke. But that's it. It take a few minutes for it to do it again just like that.
 

motoman

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Inside the Magnatron ignition module (yours is a diff model than my Intek which uses Magnatron) are two transistors . You seem to be applying 12V sometimes. The transistors run on 5 micro amps (5 one millionths of an amp?). If you have applied bat voltage the little transistors are ruined and no amount of continuity check or probing will bring them back. It is characteristic of a a failed transistor to sometimes work, but not continuously. I have never seen any Briggs discussion of the guts of the module, probably because it's Greek to many on the forums. These modules are probably encapsulated (potted- after the circuit is soldered up it is placed in a mold and a special casting resin is poured in, then cured.) The modules live bolted on to the iron of the engine which is normally a "heat sink," which draws heat away from the transistors who only tolerate up to 250F (probably less). Vibration is also the enemy. It appears the pros know well how many ignition modules are ruined with the best intentions gone wrong. These modules are rugged while also being fragile (to stray excess voltage). Well again I am on my soap box, and before you can pelt me with garbage I sign off. Your humble servant.:laughing:
 

hrdman2luv

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Inside the Magnatron ignition module (yours is a diff model than my Intek which uses Magnatron) are two transistors . You seem to be applying 12V sometimes. The transistors run on 5 micro amps (5 one millionths of an amp?). If you have applied bat voltage the little transistors are ruined and no amount of continuity check or probing will bring them back. It is characteristic of a a failed transistor to sometimes work, but not continuously. I have never seen any Briggs discussion of the guts of the module, probably because it's Greek to many on the forums. These modules are probably encapsulated (potted- after the circuit is soldered up it is placed in a mold and a special casting resin is poured in, then cured.) The modules live bolted on to the iron of the engine which is normally a "heat sink," which draws heat away from the transistors who only tolerate up to 250F (probably less). Vibration is also the enemy. It appears the pros know well how many ignition modules are ruined with the best intentions gone wrong. These modules are rugged while also being fragile (to stray excess voltage). Well again I am on my soap box, and before you can pelt me with garbage I sign off. Your humble servant.:laughing:

Most of what you just said, is completely greek to me. But, I think I understand at least some of it.

First question, if what you said applies to my magneto, would the magneto still work when I connect the test light ground (on the negative side of the battery) to the end of the plug wire? When I do that, the cylinder that still has a plug & plug wire connected is firing right. When I switch them (connecting the test light to the other plug) then the other cylinder runs fine. The engine will crank and run off of one cylinder, as long as I have that test light connected to one disconnected plug wire (disconnected from the plug)

Sorry if I didn't explain that right. I think I did. But long day at work, and my sleeping pill is kicking in..
 

motoman

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hardman to stop: Like your persistence so more blather from me. The battery is negative ground, right. That means touching the negative terminal is simply 0 volts. You also get that 0 volts anywhere on the metal frame or engine. So (If I'm reading you properly) you are grounding the spark lead . But if you accidentally put POSITIVE battery contact to the module(12V) you have instantaneously destroyed the transistors-no going back. Are we understanding the cylinder firing moves with the one module only? Remember that the failed transisors may put out an occasional spark, but be inoperative. Shaky here, but if your machine is like mine one module's behavior will not affect the other's. These magneto systems are not like auto systems and generate their own voltage without the battery . The really small time it takes to destroy a transistor would not heat up the resin body so you could smell it (like a burning electric motor or failing truck brakes on a downhill). We feel your pain and await a breakthru.
 

hntrsr

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Inside the Magnatron ignition module (yours is a diff model than my Intek which uses Magnatron) are two transistors . You seem to be applying 12V sometimes. The transistors run on 5 micro amps (5 one millionths of an amp?). If you have applied bat voltage the little transistors are ruined and no amount of continuity check or probing will bring them back. It is characteristic of a a failed transistor to sometimes work, but not continuously. I have never seen any Briggs discussion of the guts of the module, probably because it's Greek to many on the forums. These modules are probably encapsulated (potted- after the circuit is soldered up it is placed in a mold and a special casting resin is poured in, then cured.) The modules live bolted on to the iron of the engine which is normally a "heat sink," which draws heat away from the transistors who only tolerate up to 250F (probably less). Vibration is also the enemy. It appears the pros know well how many ignition modules are ruined with the best intentions gone wrong. These modules are rugged while also being fragile (to stray excess voltage). Well again I am on my soap box, and before you can pelt me with garbage I sign off. Your humble servant.:laughing:

I would love for Briggs and Stratton to come out with a test for the solid state part of the magnetroin. My problem you buy a new one and there is no way to know if it is good, You shuold be able to test the resistance in a transitor safely if you observe the correct polarity
 

motoman

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hnstr, It is frustrating to live in the digital age because just below the surface of the buttons is a very complex world few care to understand. If this forum stimulates even a few to pursue further study of e.g., transistors , this will be very good. But they cannot be understood with street sense. Far from an expert I did study this stuff many years ago. Ideas like "resistance" are really quite different when you study transistors. An education is available online , but probably somewhat frustrating. So the ignition module for most will be understood in this forum as simply "good" or "bad." Probably the best bet is to try to buy top line replacement which "should" have reliable parts inside and then do not overheat or allow stray voltage near them. Have a good holiday. motoman
 

hrdman2luv

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hnstr, It is frustrating to live in the digital age because just below the surface of the buttons is a very complex world few care to understand. If this forum stimulates even a few to pursue further study of e.g., transistors , this will be very good. But they cannot be understood with street sense. Far from an expert I did study this stuff many years ago. Ideas like "resistance" are really quite different when you study transistors. An education is available online , but probably somewhat frustrating. So the ignition module for most will be understood in this forum as simply "good" or "bad." Probably the best bet is to try to buy top line replacement which "should" have reliable parts inside and then do not overheat or allow stray voltage near them. Have a good holiday. motoman

Thanks you for that..

I put on the other magneto, checked the kill wire after it started up, and no voltage was coming through it... After about 30 minutes, it stopped and now no spark through the plug wires.. I'm thinking seriously about rewiring it without the safety switches. And "extra's"... I don't know. I might just put it away until next spring.. Luckily for me, I've got another one that works great....

Happy Thanksgiving to you and yours.. And everyone else on this forum.
 
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