Malfunctions
Causes
Order
of
Inspection
and
Corrective
Measures
G.
Only
bobbin
(hrcad
is
not
cut
(needle
thread
is
cut)
3. Retreating range
of
moving knife insufficient
* Inadequate adjustment
of
the moving knife (left-right
position of the knife shaft and thread trimming cam
inadequate).
CO
Verify
the retreating amount of the
moving
knifeand adjust the left-rightposition
of
the
trimming
cam so
that
the
retreating
amount
comes
to 2. 2.Smm
(5/64"
~3/32").
4. Tiic
bobbin
thread
position
at
trimming
time
is
not
steady
*
Due
to using
undesignated
sewing
hook
CO
Inspect and see if the sewing hook is equipped with a bobbin thread guide
groove and if
not,
change the sewing hook.
If.
Both
needle
thread
and
bobbin
thread
are
not
cut
(Stops
at
lowered
position)
1) Iwen when the pedal
is
stepped
on to the rear,
sound
of
thread
trimming magnet is
no)
heard
1. Defective thread
trimming
switch
components
* Incorrect installed position
of
trimming switch
* Inadequate contact and functioning of thread trimming
components
' Inadequate connection of the cords to (he trimming
components
(0 Step on the pedal to the rear and verify the working sound of the thread trimming
magnet. If the
sound
can
not
be heard;
CO
In the case of HITACHI motor, screw-in the thread trimming adjusting screw, and
verify
the
moving
sound
of
the
switch.
In
the
case
of
NATIONAL
motor,
exchange
the
switch.
® Inspect the continuity of all parts by a tester and measure the resistance value,
a. Inspect the
thread
trimming
switch.
Inspect the conductivity between the No.4(red) and No.6(blue) pin terminals of
12P plug and if at the pedal
stopping
position there is no
conductivity
but
there is
conductivity when the pedal is stepped to rear (thread trimming action), it is
normal. When the resistance value al conductivity time is
5n,
exchange it.
2.
Thread
trimming
magnet
is
either
disconnected
or
shorted.
(1) Inspect
the
thread trimming magnet.
Measure the resistance value between No.2(black) and No.5(brown) pin terminals of
the
I2P
plug coming
out
from the
machine
head,
a.
If
the
resistance
is 11 n
...
it is
normal.
* If the resistance is oo ... inspect the wiring and if the magnet is di.sconncctcd,
exchange it.
* When
the
resistance
is
On
...
inspect
and
sec if
the
circuit
is
shorted.
If
its
.shorted inside the magnet, exchange the magnet. After that if the magnet is
"ON"
condition, exchange the Tr23. At this point, inspect the
033.
2)
Needle
stops
midway
before
reaching
the
upper
stop
position
1.
Belt
is
too
loose
UJ)
Tighten
the
belt
somewhat.
2.
Inadequate
torque
at low
speed sewing
' Voltage is too low.
*
Faulty
condition
of
the
clutch
plate
of
the auxiliary
motor
' Motor lever
returning
spring is too weak
(.0 Inspect the voltage
of
the power source.
(2) Tighten the hinge
nut
at lever
returning
spring gradually, little at a
time.
3)
The
.sound of magnet is
heard
but
the
thread
is
not
trimmed
I. Insuffieient retreating
range of the knife or the
moving knife
forked
base
is
broken
or
insufficient
trimming power
Remove the needle plate and inspect and if the thread is not trimmed when
thread trimming operation is
performed
by the pedal, it is because
of
insufficient
retreating range of the moving knife or insufficient trimming power
(IV-5,
6).
2
The
thread
trimming
cam
and
the
roller
do
not
interlock
*
The
right
and
left
position
of
the thread trimming cam is
inadequate
'
Faulty
timing
of
the
thread trimming cam
*
The
screws
of
the
slide
shaft
collar
or
the
cam
roller
arm
are
loose
* Installation
of
parts
which are moved by
the
trimming
magnet
is
faulty
* The knife moving shaft adjusting nut screw is loose
(D
Inspect
the
knife
driving
shaft
adjusting
nut,
slide
shaft
collar
and the
cam
roller
arm not screwsfor loosened condition and correct them to the right positions.
@
Inspect
and
see
if the
trimming
arm
moves
smoothly
until
it hits
the
stopper
within
the 60°
zone
of the
main
shaft
rotating
angle
when
the
needle
tip
slips
out
from the needlehole of the needle plate. If it does not movesmoothly,verify first
if the retreating
range
of the
moving
knife is
adequate
and then adjust the right
and left position of the cam
(IV-1).
(D
Adjust
the
timing
of the
thread
trimming
cam
with
the
indicating
point
of the
hand
wheel
(IV-1).
-
30
-
To Next Page
Loading...
Need help?
General
