One Winding in Brushless Servo is 2 Ohms Higher

[691175002]

I have a brushless servo that appears fully functional but has a slight torque/speed ripple that produces waves in its final application.

The datasheet says the windings should have 4.2r of resistance, and A to C measures correctly.  AB and BC both measure 6r.  A working servo measures 4.2r across all windings as expected.

I know that typically windings fail fully open or show decreased resistance as the insulation degrades.  Any idea what could have happened here?

Unfortunately I have no idea what the electrical schematic of the motor looks like.  Maybe they split each winding into three parallel magnet wires and one got loose?

[floobydust]

I'm not sure if it's wye or delta winding.
I'd take it apart as extra ~2R is huge and would heat up and melt things, if it's a bad connection.
Perhaps the factory took a lunch break after winding one correctly.

[691175002]

For reference I took the servo apart and it is wired as a wye with two parallel windings per leg.  One of the six total windings is open and as there is no visible damage, so it looks like the only way to save the servo would be to rewind it.

[floobydust]

maybe resolder the tie point, sometimes varnish is still there. I usually see windings open-circuit at the connection points, never in the middle unless cut/chafing.