Husqvarna Viking Designer I Service Manual page 66

Fault finding diagram
The machine does not alarm when the lower thread ends.
Before doing any service clean both diodes of the lower thread sensor and remove all fluff
1. Check the lower thread sensor in the service menu by rotating the hand wheel slowly
2. Check that cables to the circuit board are correctly inserted and not damaged.
3. Try a new lower thread sensor.
4. Try a new circuit board.
The thread cutter is not working
If the step motor is not working:
1. Check that the button is working.
2. Check that cables to the circuit board are correctly inserted and not damaged.
3. Try a new circuit board
4. Try a new step motor.
If the step motor is working but it is not cutting the thread:
1. Check that the thread cutter knife is positioned correctly.
2. Make sure the pickup is moving correctly.
3. Replace the knife.
The machine does not stop when the upper thread is finished or breaks.
Check the upper thread sensor in the service menu.
If OK:
1. Check the setting of the thread take-up spring and the thread tension.
2. Check the screens between the photo-diode of the upper thread guard so that it's running
smooth.
If not OK:
1. Check that the cable to the upper thread guard sensor board is correctly inserted and not
damaged.
2. Try a new upper thread guard.
3. Try a new circuit board.
The machine stops and indicates that the upper thread is broken.
Check the upper thread sensor in the service menu.
If not OK:
1. Check that the sensor arm is correctly assembled on the spring
2. Check the setting of the thread take-up spring and the thread tension.
3. Check the screens between the photo-diode of the upper thread guard so that it's running
smooth.
If OK:
1. Check that the cable to the upper thread guard sensor board is correctly inserted and not
damaged.
2. Try a new upper thread guard sensor board.
Try a new circuit board.
The presser foot lifter does not work.
Check in service menu that the presser foot sensors are working.
If OK:
1. Check if there is contact between the buttons and the push button board.
2. Check the cables from the step motor are correctly inserted and not damaged.
If not OK:
1. Try a new sensor or a compl sewing head.
2. Try a new sewing head slave board.
3. Try a new circuit board.
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