Brother LX-200 Service Manual page 165

Problem Check Item
b. Defective Is the white lead connector
trimming (TC) connected to CN9 on the
motor. Main PCB?
Are pulses output from output
ports P74 to P77 (Pin 5 to
Pin 8) of the main CPU#1?
When the output from output
ports P74 to P77 (Pin 5 to
Pin 8) of the main CPU#1 is
Low, is the output from
transistor array QA1 Low?
Is +24V DC applied to Pins 3
and 4 of connector CN9 on
the Main PCB?
Continuity in motor harness
assy?
Correct resistance value
(approx. 43 ohms) between
each phase of the TC motor
and the COM pin?
c. Defective Is the red lead connector
trimming (TRG) connected to CN6 on the
switch. Main PCB?
Is main CPU port P44 (Pin
45) at High level when leaf
switch TR-G is open?
When leaf switch TR-G is
shorted, is CN6 on the Main
PCB shorted?
Is main CPU port P44 (Pin
45) at Low level when CN6
on the Main PCB is shorted?
When main CPU port P44
(Pin 45) is at Low level, is this
recognized by the main
CPU?
Cause
Motor harness assy not Correctly connect the
connected. motor harness assy.
Defective main CPU#1. Replace Main PCB
assy.
Defective transistor Replace Main PCB
array QA1. assy.
Continuity problem in Replace Main PCB
Main PCB. assy.
Defective motor Replace motor
harness assy. harness assy for TC
motor.
Defective TC motor. Replace TC motor.
Leaf switch assy not Correctly connect the
connected. leaf switch assy.
Continuity problem in Replace Main PCB
Main PCB. assy.
Defective pull-up Replace Main PCB
resistor R25. assy.
Defective leaf-switch Replace leaf-switch
TR-G assy. TR-G assy.
Continuity problem in Replace Main PCB
Main PCB. assy.
Defective series Replace Main PCB
resistor R29. assy.
Defective main CPU#1. Replace Main PCB
assy.
7-13
Remedy Repair
Replace
CPU#1.
Replace QA1.
Replace R25.
Replace R29.
Replace
CPU#1.
See
Section
3.3.3
3.3.4
3.3.5
3.3.3
3.3.4
3.3.5
3.5.1
3.3.1
3.3.3
3.3.4
3.3.5
3.4
3.3.1
3.3.3
3.3.4
3.3.5
3.4
3.15
3.3.3
3.3.4
3.3.5
3.3.3
3.3.4
3.3.5
3.5.1
3.3.1
3.3.3
3.3.4
3.3.5
3.4
3.6
3.3.3
3.3.4
3.3.5
3.5.1