Enduro Drive SM645B-2P Position Sensor Fix

[GerryR]

I had started another thread looking for input on a position system problem on the SM645B-2P Motor Controller.  I found from a search that this was a manufacturer's problem that was never fixed.  However, I decided to persue the issue and came up with a fix.  I hope it helps someone else to get their position system working for these controllers.  I might mention that this problem supposedly did not exist in th 2P (220V w/ Position) units but I have two 2P units with this problem.

The problem:  When removing your foot from the foot pedal, the sewing machine makes two extra cycles (stitches) before stopping.  It stops in the correct position, but always two cycles later.

Enduro SM645B-2P Position Sensor Fix:

I came up with a "partial" fix for the position sensor problem with the SM645 units.  The initial problem is that when releasing the foot pedal, the sewing machine makes two extra cycles (stitches) before stopping.  It always stops in the correct position, just two cycles later.  This told me that the control unit wants to see two pulses prior to stopping.

I took the cover off of the sensor and found two holes in the optic disk that the two sensors "look" through.  One hole is closer to the edge of the disk than the other.  The one closest to the edge is for the stop command to the controller; the other is for the indicator LED on the sensor body.  They are 180 deg. opposite each other.

I took a piece of black electrical tape and blocked the hole closest to the edge.  I then drilled two holes in the disk, one just above the LED hole, and one 0.475" counter-clockwise from that hole.  See Picture.  (My hand-wheel runs clockwise; if yours runs counter-clockwise, you will want to put the second hole clockwise from the other two, or the LED will not light in the stop position.) Both holes are, in my case, 0.216" from the edge.  I used a #45 drill bit (0.082) for the holes.  I elongated the lower LED hole slightly to compensate for the slight overshoot when the stop command was issued, so the LED would remain on when in position.  This also helps when setting up your stop position; you place the sewing machine in the position you want it to stop and rotate the sensor ring until the LED comes on.  Had I thought about it a little more before drilling the hole, I could have drilled the "stop" hole slightly ahead of the LED hole to accomplish the same thing, but you can't "un-drill" a hole very easily!

Why a "partial" fix?  Because now you cannot have a set of holes 180 deg. from the first set and be able to use the controller panel to change up or down position.  You have to physically change the sensor position if you want down instead of up, or vice-versa.  Just unplug the sensor for no position control.

I hope this helps someone.

[GerryR]

One additional Item:

                      The controller must be in the "Pu" state (Position Up) for this to work.  If in the "Pd" state (Position Down), the unit resorts to the "2-extra-cycles" condition described above!!