Bernette b77 - 12 Errors and Faults; 12.1 Troubleshooting

Errors and Faults
95
2022-08 EN 5020077.40A.04
12 Errors and Faults
12.1 Troubleshooting
Fault Cause Repair
Uneven Stitch Formation
Upper thread too tight or too
loose.
> Adjust the upper thread tension.
Needle blunt or bent. > Replace the needle, make sure that a new BERNINA
quality needle is used.
Poor quality needle. > Use a new BERNINA quality needle.
Poor quality thread. > Use quality thread.
Incorrect needle/thread
combination.
> Match the needle with the thread size.
Incorrectly threaded. > Rethread.
The fabric has been pulled. > Feed the fabric evenly.
Dust or thread remnants under
the tension spring of the bobbin
case.
> Remove any dust or thread remnants from under the
tension spring of the bobbin case.
Skipped Stitches
Incorrect needle. > Use the needle system 130/705H.
Needle blunt or bent. > Replace the needle.
Poor quality needle. > Use a new BERNINA quality needle.
The needle is incorrectly inserted. > Insert the needle with the flat side to the back as far up
as it will go into the needle holder and tighten the
screw.
Incorrect needle point. > Match the needle point to the texture of the material.
Faulty Stitching
Thread remnants between the
thread tension discs.
> Fold a piece of thin material and slide the folded edge
(not the raw edges) between the thread tension discs.
Incorrectly threaded. > Rethread.
Thread is caught in the hook. > Remove the upper thread and the bobbin case, turn the
handwheel backwards and forwards by hand and
remove the thread remnants.
Incorrect needle/thread
combination.
> Check the needle/thread combination.