Power Supply "Chirping - Janome QMP16SU Manual

2. When running the machine, the motor attains full speed prior to reaching 100% on the display.
a. This can be caused by the Speed/Needle sensor missing some of the speed pulses. First run
the Speed test from the Diagnostics menu on the display. (For more information refer to the
Diagnostics Tests section in the user manual). If the displayed value does not settle on 100 after
running the machine at full speed, there may be an issue with the motor-speed encoder.
b. Wit the machine cover open check the Control board Speed LED (D6) on the circuit board. It
should flash on/off 100 times per revolution.
c. Verify that the sensor is in the correct position and that the disk is not dirty or damaged.
d. If the disk appears to be in good condition, slowly rotate the hand wheel with power on and all
cables connected while watching the Speed LED. It should turn on and off with each of the 100
segments of the outer encoder disk. If some segments fail to cause the LED to turn on or off, the
sensor board may need to be adjusted or replaced.

Power Supply "Chirping"

A repeating "chirp" coming from the quilting machine may indicate a power supply that is shorting out or
being overloaded. The power supply is designed in a way that if there is a short or if the power draw is too
extensive, it will shut itself down. This may result in an audible "chirp." It will then try to power back up.
However, if the short or power draw is still there, it will shut down again. This process continually repeats
as long as the power switch is on, resulting in a repeating "chirp" sound.
1. The yellow/black cable that delivers 48V from the top of the control board to the motor driver board
may have the wires inverted where it plugs into the motor driver board. These wires can be removed
individually from the terminal block, so make sure when they are put back in place, the yellow wire is at
the top.
2. Any other pinching or damage to the yellow/black wires that deliver power to or from the top of the
control board.
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QMP16SU Service Manual