QMP16SU Service Manual
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board at any point during the rotation of the main shaft.
• If the encoder board is in the position stated above, but the test number is still less than 100 (but not
zero), try shifting the board more to the right so the encoder disc is closer to the sensors on the left
side of the forked board (still not touching).
• If this still does not produce a result of 100, use a tiny screwdriver to adjust the tiny potentiometer near
the bottom of the board just a few degrees either to the right or the left. Then re-run the test. If that
does not help, try adjusting the opposite direction.
• If none of the above adjustments results in a test output of 100, the main shaft encoder board and
cable should be replaced.
If the result of this test is zero:
• Check the main shaft encoder cable and be sure it is not damaged and that it is plugged in properly to
the Control board and to the Main Shaft Encoder Board.
• If you do not have any flashing LEDs on the Main Shaft Encoder Board after checking the cable, the
board and cable should be replaced.
Y-Motion Sensor Test
Use the Y-Motion Sensor test to verify functionality of the Y-axis stitch regulator encoder (the encoder
mounted to the rear power pod side machine wheel).
• Press the Y-Motion Sensor test button. Slowly move the machine toward and away from you. You
should hear a pulsing beep that pulses faster as you move the machine faster. A solid beep, no
beep, or periods of irregular beeping (with constant motion) indicate a problem with the Y-axis
encoder.
NOTE
: The most likely cause of a problem is a stitch regulator wheel that is not making consistent
contact with the track. Check the spring tension on the sensor assembly on the machine to assure
that it will easily return to the fully extended (down) position after being compressed. Also assure
that the track is straight with no dips or indentations and that it is clean and free of contamination.
Other causes are an unplugged or damaged cable or possibly an issue with the main control board.
Needle Sensor Test
This message appears when the machine is trying to position the needle, but the machine is going too
slow or too fast. this can occur when a board is changed or the dynamics of the machine have changed.
Running burn-in will usually correct this. If the main shaft encoder is defective, the machine might not run
burn-in because the main shaft encoder is not detecting the 100 pulses per revolution of the encoder disc.
The Speed LED on the left side of the main shaft encoder should flash on and off when the hand wheel is
turned. If it does not flash at all and does not change when the small pot is adjusted, try a new main shaft
encoder.
When to use the Needle Sensor Test
This tests the optical sensor associated with the inner region of the main shaft encoder. Use to verify
Needle Up and Needle Down stopping positions and when the Needle Sensor Failure message occurs.
How to use the Needle Sensor Test
As you rotate the hand wheel, you should hear a solid tone start when the needle is in the UP position and
then stop when it reaches the down position.
