Malfunctions
Causes
Order
of
Inspection
and
Corrective
Measures
• Motor lever returning spring too weak or too much
clearance between the worm gear of low speed rotation
or brake lining of (he hand wheel gear and the clutch
plate
i) Rotate the
machine
at
high
speed,
release
your foot
from
the
pedal
and at the
same time lift up the motor lever and if the machine stops at this time, the
above-stated spring is
too
weak.
a. In the case of HITACHI motor, tighten the motor lever returning lever
adjusting screw and make the spring stronger.
(D In the
case
of
HITACHI
motor
and
NATIONAL
motor,
screw
in the
adjusting
screw of the gear head part to lessen the moving range of the motor lever.
2.
Malfunction
of
sensor
components
' Malfunction of needle positioning sensor
a. Inadequate contact of the cord connecting the sensor to
the
control
box or wrong connection.
b. Defective connection of the electrical wiring from the
control box to the transformer or inadequate plug-in of
3P
connector.
c.
6A
and
lA
fu-ses
of
the
control
box
blown
out.
(1)
Inspect the wireconnectionof power source to the control box.
(2) Inspect and see if the fuse is disconnected or not.
(D
Remove
the beltof the
machine
from
the
pulley,
turnoverthe
grey
capof the
12P
connector, turn the power switch on and while measuring the DC voltage between
the No.l(white) and No.6(blue) terminals with the direct wire lOV range (black
lead rod to No.6), rotate the pulley with the hand and if the voltage is
OV
between
the
synchronizing
zone
and
shows
5V at
other
areas,
it's
normal
and
if
it's
.same
condition
between
No.4(yellow)
and
No.6(blue),
it's
normal. But in
either
case, if
the needle of the tester should remain showing
OV
or SV even once, verify the wiring
connections and they are not in error, exchange them.
J. Kvcn when (he pedal is
set at stopping position,
the
machine
runs
at
low speed
1.
Inadequate
adjustment
of
low speed sewing switch
'D
When
the
pedal
is
lightly
stepped
on and if the
moving
sound
of the motor
lever
part
can
not
be heard,
adjust
the position of L.SW.
Release the plugged-in cord of the motor lever and while lowering or separating the
motor lever lightly, inspect the continuity between the cords V3(red) and Y7(grey)
which
come
out
from
the
motor
lever.
If they do not become "ON" or
"OFF",
exchange the switches.
2.
Connector
is pulled
out
(X)
Verify the plugged-in condition of the 12P connector and 9P connector (blue).
3.
Defective
brake
of
the
motor
magnet
X)
Readjust
the
clearance
of the magnet brake.
(D
Inspect
the
wiring
to
magnet
brake
between
X3- X4
tcrininal.s.
(D Inspect the conductivity of the magnet brake of motor and if resistance is about
90n
(Hitachi),
60f2
(National)
its
ok
if
not,
® Exchange the magnet brake.
4. Inadequate adjustment
of
stop
position adjusting
knob
D Try to rotate the adjustingknob toward the "FAST" direction and see.
® Inspect the cord of the adjusting knob inside the control box.
K.
Needle
breaks
at
(he
start
of
sewing
Unusual
sound
is
heard
from the bed part
I.
Malfunction
of
the
movement
of
the
safety
device
*
Safety
magnet
cord
is disconnected.
Remove the needle, step on the pedal to rear and when the pedal is stepped on to
the front quickly,verify to seeif the pedalcannot besteppedon before the stopping
position, (National) or becomes idle stepping (Hitachi).
If it can be stepped on, adjust the safety device stopper.
® Verify and see if the
moving
sound of the safety magnet can be heard at the
trimming time. If it cannot be heard, re-adjust the installed position of the safety
lever so
that
the
movement
of
the
safety
lever will
become
smooth.
®
Re-adjust
the installed positionof the pedal
connecting
rod.
®
Measure
the
resistance
of the safety
magnet.
When
the
resistance
between
the
terminals Y2~Y5 of the 9P plug is 0 or the connection is bad or the safety
magnet is defective, (change the
magnet)
-
32
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