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Re: (ET) Running but still odd things, tiny screw head on the thermal breaker, left or right?

Perhaps. There is another way to find out: Swap in another armature after swapping the end cap. One thing about large frame motors: The magnets often blow so you wind up with a number of spare armatures and caps. The longer motors tend to blow up the armatures, so you wind up with a bunch of long cases with good magnets.
Will try this tomorrow. Normally when I see the armature go bad the motor will tend to "cog" as power is lost in the shorted winding. Hopefully it's simple. 

The bigger problem is why the ground fault in the drive motor.

C

On 5/21/2019 7:41 PM, Chad Bush wrote:
The statement about the winding fault being relative to armature position is incorrect. There can be inter-winding faults, as well as a winding-rotor fault. Only way to isolate it is pull the armature and test on a growler. The brushes excite windings that are common from brush-brush and short windings that were once excited to remove stray currents, so they serve a dual-purpose. Due to that nature, it is also possible the commutator just needs undercut. That, too, can cause wierd issues. 

Chad

On May 21, 2019 6:22 PM, Chris Zach <cz alembic crystel com> wrote:

    Continuing the troubleshooting I took a look at the deck wiring by
    removing the wire cover plates. All looked good so I started taking off
    the motor wires to isolate the problem.

    Sure enough with the center motor disconnected (the oldest one) the
    ground fault disappeared. So it's in the motor. I took this one
    apart to
    check and lubricate the bearings and clean out all the accumulated dust
    and junk, so it's not that.

    Either it's a short in the armature or in the brush housing. I don't
    think it is the armature, as a winding short would only ground fault in
    certain rotation points and this is faulting everywhere. So I'll pull
    off the cap tomorrow and have a look at the two posts. One of them
    might
    have a damaged insulator sleeve....

    That and fixing the wire on the main motor with a new lug should fix
    all
    the problems until I can get around to dropping and pulling the drive
    motor. Maybe in the fall because I need it now for mowing.

    C

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