QMP16SU Service Manual
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Indications of Speed/Needle Position Sensor Failure
1. A message on the display indicates a
Needle
Sense Failure
.
NOTE: First check the hand wheel to
see if it will turn. Often this message will
occur when the hand wheel cannot turn;
for example, when the machine has a
thread lock. Remove the thread lock and
then check the machine for the error
message.
Make sure the Speed/Needle Sense
cable is properly connected to the
control board mounted inside the front
cover of the machine.
a. With the control board accessible and all
cables attached, power up the machine
and verify that the green LED D4 Needle
turns on and off to indicate Needle Up
and Down positions as you rotate the
hand wheel (D4 works the same way as
the Needle LED that is mounted to the
internal Needle/Speed Sensor board).
b. If the LED does not turn on or off
properly, determine whether the
encoder disk has been damaged or is
dirty, and make sure the sensor board is
positioned properly.
c. Check that the cable from the Control
board is plugged firmly into the sensor.
Control Board mounted to the inside of front
cover
Needle/Speed Sensor Board
