# How do I test a solid state armature



## speedyox (Aug 12, 2005)

I have a B/S 142802 5hp 4 stroke engine that has no spark. When the whole thing is assembled, the stop switch is shorted. When I unhook the armature, the stop switch works fine. My Ohm meter tells me that the connector tab on the armature is electrically connected to the metal core (which gets screwed to the block, shorting the stop switch) 
Am I wrong here, or does this show that my armature is bad? BTW- The spark plug side of the armature is NOT shorted to the core or the connector tab.

Another way to ask this is:

What points are supposed to be ground and what points are supposed to be switched to ground or isolated from ground?


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## bbnissan (Nov 7, 2004)

An ohm meter isn't going to tell you much about a coil. You need to reset the gap on the coil using a business card or, even better, a dollar bill. After that, disconnect the kill wire and check the spark. I would suggest going to the autoparts store a buying an adjustable spark tester to check the spark. Stay away from the cheap spark testers with no adjustment...they will only tell you the coil is firing, but won't indicate how strong the spark is. With an adjustable spark tester, you can set the spark gap to about 1/4"...if the spark can jump that gap it's plenty strong to run the engine.

There are other ways to check a coil, but they require a special machine.


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## speedyox (Aug 12, 2005)

*been there, done that.*

I've got an adjustable spark tester, and I have tested the stop switch. The problem was a reed switch I didn't see before (it was under a plastic shroud) that grounds the stop unless the grass chute is oriented just right. So now the mower runs. Thanks for your ideas though.

The spark I get is weak though. The Briggs and Stratton service information I have read said that you should be able to get at least 20kv on the secondary side of the armature. With the ignition working 'correctly' and the armature gap set at .012 I can only get spark accross a gap .129" or less (which is between 10 and 15 KV on my tester). With the armature gap set with a dollar bill (.0055") I can get a spark up to .307". For reference, the two other push mowers (craftsman and honda) I have in my shop can throw a spark across a .460" and .550" gap respectively.


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