Bernina 900 electronic Service Manual page 32

Correction of thread tension:
1, Rotate the thread tension nut down-
wards (tension reduction) until the
weight rnoves easily The thread bet-
ween the reel pin and the guide eye
must be stack.
2 Rotate the thread tension nut upward
1s'° l
i
until take-ott speed attains the speci-
tied value of 55 mm in 30 ` 10 sec,
3, Adjust the thread tension nut to the
mark on the frame cover.
If the mark on the thread tension nut
does not correspond with that on the
frame cover, loosen mounting screw (146)
of thread lension nut (10) and rotate it
until the marks match. Now, press thread
tension nut and shaft against each other
SO that curved spring washer (148) which
is situated between the thread tension
nut and the tension support, is tightened.
This produces a braking effect Tighten
screw (146).
Fig 56
146
148 147
Fig 57
30