Pfaff 571 Instruction Manual page 122

Check list
Check list for correcting problems with the thread trimming device
Problem
The bobbin thread has not
been cut
After trimming the needle
thread is too short
6
Cause
Thread catcher is too high,
incorrect position of the thread
catcher
Knife pressure is too low
Tension release is not functioning
Parameter 707 (tension release
time)
Tension release solenoid is not
drawing thread through
Needle thread is being pulled into
the bobbin thread position on the
catcher
Correction
Check and adjust the position of the
catcher (see Chapter Position of the
thread catcher Page 4)
Adjust the knife pressure (see
instruction manual Chapter Knife
position and knife pressure)
Check/adjust tension release (see
instruction manual Chapter Tension
release)
Check/adjust (see instruction manual
Chapter Parameter settings)
Increase value for Parameter 719
(Tact retaining current)
Check and adjust the position of the
catcher (see Chapter Position of the
thread catcher Page 4)
Check/adjust control cam time (see
instruction manual Chapter Neutral
position of the roller lever / Radial
position of the control cam)