The Speed At Which The Machine Operates Cannot Be Adjusted; The Needle Does Not Stop In The Up Position; The Machine Does Not Operate If The Reverse Sewing Button Is Pressed Or Does Not Operate At A Slow Speed If The Button Is Pressed While The Machine Is Running - Brother BL6200 Service Manual

PROBLEM
31. The speed at which
the machine
operates cannot be
adjusted.
32. The needle does
not stop in the up
position.
33. The machine does
not operate if the
reverse sewing
button is pressed or
does not operate at
a slow speed if the
button is pressed
while the machine
is running.
(However, the
machine does not
operate at slow
speed when the
foot controller is
being used.)
CAUSE
1. The output from the transformer is
incorrect. The voltage between pins 5
and 6 of the transformer should be
approximately 8V AC.
2. The voltage between the S V and GND
on the motor control unit is incorrect. It
should be 5±0.25 V DC.
3. The voltage between pins 2+ and 3- on
the SS-VR PCB does not stay between
0 and 5 V DC when the power is turned
on and the speed adjustor is slid to the
maximum.
4. Other causes.
1. The position of the NP sensor shutter is
incorrect.
2. The motor control unit is installed
incorrectly. It is loose or slanted.
3. Inferior BW switch.
The resistance between pins 1 and 2 of
connector CN5 (black) should be less
than 1Ω when the BW switch is turned
on and ∞ when the BW switch is
turned off.*
4. Other causes.
1. The BT switch dose not work.
2. Inferior BT switch. The resistance
between pins 1 and 2 of connector CN6
(red) should be less than 1Ω when the
BT switch is turned on and ∞ when the
BT switch is turned off.*
3. Other causes.
* Be sure to turn off the power and remove from the PCB the connector.
Replace the motor control unit
Replace the motor control unit.
Replace the SS-VR PCB unit.
Replace the motor control unit.
Check and adjust if necessary.
*Refer to P.48.
Install the motor control unit correctly.
Replace the BW switch.
*Refer to P.51.
Replace the motor control unit.
Check and adjust if necessary.
*Refer to P.50.
Replace the BT switch.
*Refer to P.50.
Replace the motor control unit.
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CORRECTION