3. Other
Under Thread Control (UTC) Adjustments
NOTE: This section is intended for machines that feature UTC sensors.
The primary purpose of the UTC, shown in Figures 3-14, 3-15, and 3-16, is
to signal when the bobbin thread runs out or breaks. It features a sensor arm
that is bumped by the bobbin thread during every stitch.
When the sensor arm is not bumped for several consecutive stitches, the
machine stops sewing, backs up, and beeps. The LCD will display the a bobbin
thread error message.
Two screws attach the UTC to the underside of the needle plate bracket, in
front of the rotary hook. The UTC only needs to be adjusted in its
forward/backward alignment. If the UTC is too far toward the front of the
machine, it will be unable to detect the bobbin thread and will give false
bobbin error messages. The UTC may also perform unreliably if it is too far
toward the back of the machine.
The UTC also has a retaining tab that fits into a slot on the rotary hook.
This tab prevents the inner basket of the hook from rotating.
When the UTC is in the correct position to detect the bobbin thread, the
retaining tab will automatically be in the right position to hold the basket,
as shown in Figure 3-16.
