-72-
4. The motor
starts, then
stops
immediately.
1. Is the sensor PC board assembly installation normal?
Is it floating loose or tilted?
2. Others
1. Correct the installation.
2. Replace the main PC board
assembly.
5. Speed cannot
be adjusted.
1. Is the transistor output normal? Is the voltage
between Pins 9-10 of the transistor approximately 9
volts?
2. Is the voltage between 5V and ground on the motor
control PC board normal?
5±0.25 VDC
3. When the power is switched ON and the speed
adjustment control is slid, does the voltage between
(+) 2 and (-) 1 of the connector on the SS-VR PC
board vary between 0 and 5 VDC?
4. Others
1. Replace the main PC board
assembly.
2. Replace the main PC board
assembly.
3. Replace the SS-VR board
assembly.
4. Replace the main PC board
assembly.
6. Needle does
not stop in the
up position.
1. Is the NP sensor shutter position normal?
2. Are the sensor PC board assembly and main PC
board assembly installation normal? Are they
floating loose or tilted?
3. Is the bobbin winder switch normal?
Resistance between 1-2 on connector CN3 (red)
On..........1
Ω
max.
Off..........Infinite
4. Does the voltage between (+) 4 and (-) 3 on
connector CN5 change between 0 and 5 V when the
sewing machine is turned by hand?
5. Others
1. Check and adjust as
necessary.
2. Correct the installation.
3. Replace the bobbin winder
switch assembly.
4. Replace the main PC board
assembly.
5. Replace the main PC board
assembly.
7. The sewing
machine does
not turn when
the reverse
sewing switch
is pressed or if
the switch is
pressed during
operation, it
does not go into
low speed.
(However,
when the foot
controller is
used, the speed
is not supposed
to become slow
speed.)
1. Does the reverse sewing button operate correctly?
2. Is the reverse sewing button normal?
Resistance between 1-2 on connector CN2 (yellow)
On..........1
Ω
max.
Off..........Infinite
3. Others
1. Check the mechanism and
adjust as necessary.
2. Replace reverse sewing
switch assembly.
3. Replace the main PC board
assembly.
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