9N Front Mount Points Burning Out

Jeff

and OPEN condensor would allow the points to burn.. etc.

Big difference in 'OPEN' and SHORT' electrical faults...

A shorted condensor would in effect short the points.. meaning, electrically, they would / could never open.... thus no spark.. thus no tractor running..

soundguy

I thought the condenser was the path to ground when the points close & it's purpose was to absorb(?)the current surge when the points break, thus eliminating the arc.

So, how is the ckt completed across the points if you have an open condenser? Seems like the effect of an open vs. shorted condenser would be the opposite of what you describe.

Be merciful w/ your answer, as I must be more electrically challenged than I thought.

Jeff

""I thought the condenser was the path to ground when the points close ""

The points have a fixed and moving contact... one side of the points is hooked tot he primary wire coming from the ignition coil.. the other sid eof the points are grounded to the tractor frame... thus.. when the points are closed.. they are their own ground.

""So, how is the ckt completed across the points if you have an open condenser?""

Same way a spark plug or lightning works... when the condensor is open, there is an arc that jumps the points.. pitting and burning them.. IE.. they are a sparkgap.. think of the capacitor as a 'debouncer' for a switch... google that term if you don't know what it means.

""Seems like the effect of an open vs. shorted condenser would be the opposite of what you describe.""

Uh.. maybee to someone who hasn't studdied electronics i guess.

Think about it.. if a condensor is shorted, AND across the points.. when the points open mechanically.. they will not open electrically.. thus no spark...

soundguy

Jeff

soundguy

Also, are you cleaning any oil (even from fingerprints) off of your feeler gauge before using it in the points, with electrical contact cleaner and a lint-free cloth?

Even cleaning NEW points (after setting them) with contact cleaner and allowing them to air-dry (with the points OPEN) is a GOOD idea.

Sean..... .the ONLY thing that'll BURN yer points is NO RESISTOR. Its the LAW, Kirchhoff's Law.

It wouldn't be the first time the "infamous ballast resistor" has been miss-wired by an electrically challenged shadetree mechanic. tip: does the ballast resistor under yer ampmeter gitt HOT??? .....burnie-burnie HOT???

Since you claim you've replaced yer condenser everytime you've replaced yer points, I'm gonnna discount an OPEN condenser as cause of burning the points.

Nice series of pictures BTW. But strangely enuff, yer complaining about burned points and didn't show a really CLOSE-UP picture of yer suspect burned points. Don't miss-confuse normal points metal contact wear that you see with burned points.

Surprizingly enuff, yer elcheapo voltmeter will tell you iff'n yer points are burned by changing the top terminal volts from 2.5-3.0 to a BURNED POINTS 3.5-4.0 volts. And iff'n yer constantly reading about 6.3-volts, yer infamous ballast resistor is incorrectly wired. Isn't that amazing???..... ..Dell, yer self-appointed sparkie-meister

I can't recall who has posted on here about the "made in the land of almost right" resistors being of a fixed (probably LOW) resistance.

donb commented a few days ago he can get $$$$ OEM-quality ballast resistors, or the el-cheapos, and he commented it was tough to sell the quality $$$$ ones vs. the cheaper units.

An "OPEN" condenser is the most likely culprit, and while most are "open" right outta the box, it's hard to gitt 3-boxes innna row with open condenser. But that is what Sean claims.

As you know, it takes specialized test equipment to test condensers with enny degree of certainty. The old fashioned ohm-meter surge test would "fail" small condenser values as all being "open". And digital meters don't even swing.

Condensers by their very concept are 2-conductors separated by an insulator, therefore by definition, an "open circuit"..... ....Dell

Cheap points

Bad condenser

Worn points screws causing points to close & burn

No star washer under the points, causing them to slip & burn

Other less likely causes, but possible, are slop in the distributor shaft or coil voltage problems.

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Roger in Michigan