ANNEX
ޓ
TROUBLE SHOOTING - COVER HEMS
- irregular loop formation on the chain needles -
When chain needles start rising from their lowest positions, Chain looper also starts its motion
from its far right position to the left. Turn handwheel towards you to bring Chain needles up
and make sure if Chain looper passes into loops of Chain needle thread behind each needle.
See cover hem stitch formation on page
ޓ
. However, it is possible that some irregular loops
will appear on the chain needle threads. In that case, the chain needle threads will not be
positioned correctly and will fall down to the right or left (Fig.1).
As result of the above, the following problems may happen.
1.
Cover Hem (Narrow & Wide)
If
"L2"
needle falls into
its
needle thread loop (Fig.1-2). Check position of chainstitch
eccentric (0.5-1.0mm). See page 11 for adjustment. Check clearance between chain looper
and
"L0 / L1"
needle. If sewing result is the same, replace chain looper.
2.
Triple Cover Hem
If
"L2"
needle falls into the Red needle thread loop (Fig.3). Check if the tension is correctly
set. Check the chain looper clearance and orbital timing
"L0-L2"
. See page 11 for
adjustment. If sewing result is the same, replace chain looper.
3.
Triple Cover Hem
If
"L2"
neelde falls into its neelde thread loop (Fig.4). Replace chain looper.
4.
Cover Hem (Narrow & Wide)
If
"L2"
needle falls into both of the
"L2"
and
"L1"
neeldle thread loops (Fig.5).
Replace chain looper.
5.
Cover Hems
If
"L0"
or
"L1"
needle thread is pulled to the right (Fig.6). Check and make sure that the
"L0"
or
"L1"
needle is not touching the needle plate hole. When checking the above, use
new needle.
c
Summary of Contents for 745 -
Page 1: ...745 845 SERVICE MANUAL 2 2 5 5 1 3 5 NA 6 0 B 1 2 1 T P T P...
Page 18: ...a HEIGHT AND ALIGNMENT OF CLOTH PRESSER BAR 4a 5 b c 4 7mm...
Page 24: ...TIMING OF LOWER LOOPER 8a A B C D b a 5 2mm R1 Fig 1 Fig 2 Fig 3...
Page 51: ...ANNEX SETTING POSITIONS OF SL DF DIALS b c f d g e 2 1 C B A...
Page 61: ...M E M O...
