Operation Of Main Motor Is Not Stable, Maximum Speed Operation Is Not Possible, Or Speed Cannot Be Adjusted; Correct Patterns Are Not Created; Buttonholes Are Not Stitched Correctly; Manual Operation Of Feed And Zigzag Pulse Motors Is Not Possible - Brother PE-300S Service Manual

PROBLEM
5. Operation of main 1. When turning on power and moving speed
motor is not
stable, maximum
speed operation
is not possible, or 2. When turning balance wheel opposite its
speed cannot be
adjusted.
3. When turning balance wheel opposite its
4. Others
6. Correct patterns 1. Is resistance of pulse motor connector pins as
are not created.
2. Remove power source
3. When the balance wheel is turned slowly, do
4. Others
7. Buttonholes are 1. Is the stitch foot set correctly?
not stitched 2. Is the resistance between pins 4-5 of the
correctly.
3. When the buttonhole lever is lowered and in
4. Others
8. Manual operation 1. Do manual keys of feed and zigzag pulse
of feed and
zigzag pulse
motors is not 2. Are the resistances between pulse motor
possible.
3. Others
9. Vertical 1. When the switches are flipped off and on, are
movement of
needle bar and
backstitch
operation are
2. When the balance wheel is turned slowly, do

abnormal.

3. Is the bobbin winder switch turned off?
4. Others
CHECK
slide, does voltage between pins 3 and 7
connector CN4 (for speed slide) change from 0
to 5 VDC?
normal rotation direction, do voltages between
pins 1-4 and between pins 2-4 of NP sensor
connector (CN9) fluctuate between DC 0-5V?
normal rotation, does voltages between pins 2-
3 of speed sensor connector (CN6) fluctuate
between DC 0-5V?
follows?
Zigzag (CN10) ... 1-2,3-4 → 8-10 Ω
Feed (CN11) ... 1-2,3-4 → 8-10 Ω
2
Is voltage as follows between pins 2 and 3?
Pins 2-3 DC 18-30V
the NP sensor connector voltages fluctuate
between DC 0-5V?
junction board BH connector (CN10) normal?
When buttonhole lever is lowered 1 Ω or less
When buttonhole lever is raised
the conditions below, is the resistance
between pins 1-2 and 2-3 of the junction board
connector(CN10) normal.
Between 1-2 Between 2-3
Button hole lever is
pulled forward .......1 Ω or less
Buttonhole lever is
∞
pushed back ........
motors operate correctly?
Does the LCD change?
connector pins as indicated below?
Zigzag (CN10) ... 1-2,3-4 → 8-10 Ω
Feed (CN11) ... 1-2,3-4 → 8-10 Ω
the resistances between both sides of the
SSVR board assembly switches 1 Ω or less, or
over ∞?
the voltages of pins 1-4 and 2-4 of the NP
sensor connector (CN9) fluctuate between DC
0-5V?
1. Exchange SS (VR) PC board assembly.
2. Replace NP board assembly.
3. Replace power supply unit assembly.
4. Replace SS PC board assembly.
1. Replace the pulse motor which shows an
2. Replace NP board assembly.
connector (CN13).
3. Replace NP board assembly.
4. Replace main PC board assembly.
1. Check stitch foot.
2. Adjust buttonhole lever or replace BH switch
∞
3. Adjust buttonhole lever or replace BH switch
∞
1 Ω or less
4. Replace main PC board assembly.
1. Replace main PC board assembly.
2. Replace the pulse motor which shows an
3. Replace main PC board assembly.
1. Exchange SS (VR) PC board assembly.
2. Replace NP board assembly.
3. Adjust the bobbin winder mechanism.
4. Replace main PC board assembly.
- 51 -
REMEDY
abnormality.
assembly.
assembly.
abnormality.