Brother PC6000 Service Manual page 32

HOW TO ADJUST ELECTRONIC ELEMENT
* You must turn off the power and remove connectors from printed circuit boards before measuring resistance.
PROBLEM
1. When power is turned
on, buzzer does not
sound and nothing
appears on display.
2. After the power is
turned on, pulse
motors do not return to
their home positions
with respect to the
needle position.
(Zigzag pulse motor
when needle bar is
raised and feed and
side feed pulse motors
when needle bar is
lowered.)
3. Pattern cannot be
selected.
4. Main motor does not
run.
CHECK
1) Has the display contrast been adjusted?
2) If the voltage between both inlet terminals is
measured when the power cord is plugged in, is the
standard voltage (120 VAC, 220V, 230V, 240V)
displayed?
3) When power switch is set to on, is resistance
between both ends less than 1 W?
4) Remove connector CN13 from the power supply
board, and check following voltages using a tester:
Voltage between pins 2 and 3 should be 5 VDC.
Voltage between pins 4 and 5 should be 20 to 30 VDC.
5) Is fuse blown?
6) Others
1) Are the resistances between the connector pins given
below normal for the pulse motors which do not return
to the home position?
(CN2)........ 1-3, 2-4 ® 8-10 W
Zigzag
(CN4)........ 1-3, 2-4 ® 8-10 W
Feed
Horizontal (CN1)........ 1-3, 2-4 ® 8-10 W
2) Set the home position for the same pulse motors
irrespective of needle position.
3) Is a fuse blown?
4) Is the voltage between pins 4-5 normal when the
connector (CN13) which is output from the power
supply board is disconnected?
Between 4-5 20-30 VDC
5) Others
1) Does switch on SS PC board remain pressed?
2) When the foot controller is connected, does it remain
depressed?
3) Others
1) Does balance wheel rotate easily?
2) Is main motor connector (CN2 on power supply unit)
attached properly?
3) Is resistance of both ends on main motor connector
(CN2 on power supply unit)
120V spec 30-50W or
220-240V spec 110-150W?
4) Do start/stop switch, backstitch switch, needle
position switch, and thread cutter switch operate
correctly?
Resistances between ends of each switch should be;
under 1W when switch is pressed.
infinite when switch is released.
5) Is presser foot lifter lowered? Does presser foot
switch operate correctly?
When presser foot lifter is lowered, voltage between
pins 2-1 of fabric thickness detector (CN6) is under
2VDC.
When presser foot lifter is raised, it is over 3VDC.
6) Others
-30-
REMEDY
1) Adjust the contrast.
2) Replace the power cord.
3) Replace power supply unit
assembly.
4) Replace power supply unit
assembly.
5) Replace fuse after correcting defect
that caused fuse to blow.
6) Replace main PC board assembly.
1) Replace the pulse motor which
shows an abnormality.
2) Replace NP board assembly.
3) Replace fuse after correcting defect
that caused fuse to blow.
4) Replace power supply unit
assembly.
5) Replace main PC board assembly.
1) Adjust or exchange SS PC board
assembly.
2) Check foot control unit operation.
3) Replace LCD module, or main PC
board.
1) Adjust mechanical positions to
reduce the heavy torque.
2) Check connector connection.
3) Replace main motor.
4) Replace SS PC board assembly.
5) Check fabric thickness detection or
replace fabric thickness sensor
assembly.
6) Replace main PC board or power
supply unit assembly.