While the current MD601/611 Series is a dedicated motor for each sewing machine model, the
general-purpose thread trimming motor MD621/MD631 with general-purpose functions is a model
with integrated functions.
This motor can be mounted on the machine and used by reading in the sewing machine model
name. This motor is applicable for lockstitch sewing machines, special applications, chain stitch
sewing machines and overlock sewing machines. (Refer to the list of machine head setting modes
for details on the usable sewing machines.) By adding the optional functions, expanded functions
can be used with the sewing machine and peripheral devices. The motor power is 550W, and the
different voltage specifications are the same as the conventional models.
2. Features
1. Mounting on lockstitch, special, thick fabric, chain stitch or overlock sewing
machines
This motor can be set on each sewing machine with the machine head setting mode.
Using key operations on the box built-in panel, select the sewing machine model name from
machine head setting mode.
When the model name is set, the sewing machine model's thread trimming timing, input/output
assignment, rotation speed, motor forward rotation/reverse rotation and motor's optimum
torque, etc., will be set automatically.
2. Input/output signal functions can be selected and functions can be set
The optional inputs and optional outputs can be set with the box built-in panel.
3.1 Selecting the optional input/output functions
3.2 Setting the optional output timing
3.3 Setting the trigger (ON or OFF) conditions
3.4 Setting the time
3.5 Selecting the output operations (timer, momentary, alternating operation, etc.)
3.6 Setting the input/output signal logic
Note) Refer to the Product Manual Technical Information II for details on setting these
functions.
Refer to the Instruction Manual for the connector layout diagram.
3. The panel built into the control box has functions equivalent to the F-40
panel.
4. The F-20, F-40 or F-100 panels can be used as options.
The fabric end sensor II (connected to F panel), fabric end sensor IV, B sensor, bobbin thread
detector, and standing work treadle can be used.
General-purpose specifications : MD6∗1-1G
B891 specifications: MD6∗1-14
The motor pulley diameter is identified with G and F in the 11-digit specifications.
(G indicates ø105 and F indicates ø90.)
There are two motor pulley diameters for the general-purpose specifications. Select the
specifications according to the sewing machine model.
Motor pulley diameter ø105B276 Covering series, SBL, overlock series
Motor pulley diameter ø90B776, B291, B942, B842, B737
Motor pulley diameter ø80B891 series
B891 series specifications
(sewing machine and set specifications, packaging)
B891 series specifications pulley ø80 treadle (forward 1st step, backward
2nd step) 3500rpm
Machine head set (Set to B891) With B891 synchronizer
– 2 –
(Note 1) The B891 series specifications do not have the outer panel F-40. The built-in panel is
used.
If the outer panel is required, purchase it as an independent part. (F-40HB panel, panel
installation plate) The model code is 137-207-712-16.
(Note 2) The motor pulley is an aluminum taper pulley. A commercially-available taper pulley can
be used.
(Note 3) The motor pulley differs according to each sewing machine model. Refer to the separate
list of machine head setting modes to select and use the appropriate motor pulley
diameter. Use of a non-specified pulley will prevent the sewing machine from operating
in the optimum state.
MD-6□1
2: Single phase 50/60 Hz Voltage 100V
3: 3-phase 50/60 Hz Voltage 200V
General-purpose specifications : MD6∗1-1
B891 specifications: MD6∗1-1
The motor pulley diameter is identified with G and F in the 11-digit specifications. (G
indicates ø105 and F indicates ø90.)
There are two motor pulley diameters for the general-purpose specifications. Select the specifications
according to the sewing machine model.
Motor pulley diameter ø105B276 Covering series, SBL, overlock series
Motor pulley diameter ø90B776, B291, B942, B842, B737
Motor pulley diameter ø80B891 series
(Note 1) The B891 series specifications do not have the outer panel F-40. The built-in panel is
used.
If the outer panel is required, purchase it as an independent part. (F-40HB panel, panel
installation plate) The model code is 137-207-712-06.
(Note 2) The motor pulley is an aluminum taper pulley. A commercially-available taper pulley can
be used.
(Note 3) The motor pulley differs according to each sewing machine model. Refer to the separate
list of machine head setting modes to select and use the appropriate motor pulley
diameter. Use of a non-specified pulley will prevent the sewing machine from operating
in the optimum state.
B891 series specifications (sewing machine and set specifications,
packaging)
B891 series specifications pulley ø80 treadle (forward 1st step, backward
2nd step) 3500rpm
Machine head set (Set to B891) With B891 synchronizer
– 3 –
4. Combinations with sewing machines
4.1 Combination with Brother sewing machine
(1) Single needle lockstitch sewing machine (forward rotation)
Tacking and set length stitching can be set. (Functions equivalent to F-40)
The machine head can be set. The rotation speed, memory switch, parameters and input/output,
etc., can be set.
4.3 Operation panel (option)
F-20, F-40 or F-100 can be connected.
The fabric end sensor II, fabric end sensor IV, B sensor and bobbin thread sensor can be
connected.
4.4 Standing work pedal (option)
The variable speed pedal or two-speed pedal can be connected.
ø80 is for B891 seriesø80 is for B891 series
ø90 is standard (ø105)ø90, ø105
ø105 is for Covering series, overlockø105 is for Covering series, overlock
Control PCB has been newly addedUse not possible
Power supply PCB←
Treadle unit has been newly installedUse not possible
Transformer has been newly installed
(30V, 24V)
Built-in panel has been newly installed None
Motor fixing frame← Color is different
Box top (ADC)← Color is different
Box bottom (plastic)← Color is different
Front lidUse not possible
Only 30V cannot be used
– 4 –
6. Automatic presser lifter operations and treadle operations
If using a solenoid-type or pneumatic-type presser lifter device, make the following settings.
1. Set DIP switch 1-3 on the control PCB to ON.
ON: Needle starts moving after the presser lifter is lowered. (Includes delay time)
2. If you would like to use pressure variation at the forward 1st step to raise and lower the presser
foot using the treadle
At the time of shipment, this is set to the forward 1st step, so use a screwdriver to press inside
the hole at the bottom of the treadle lever on the treadle unit. The spring position at the forward
1st step will be changed automatically to the forward 2nd step. (The treadle can then be used
without needing to be removed.)
Note: When using the forward 2nd step setting, be sure to set DIP switch 1-4 to ON.
Because the forward step has been changed from 1st to 2nd, this will set a delay in the motor
starting point when the treadle is pressed forward.
3. If using a commercially-available solenoid-type presser lifter device
Use a solenoid with a coil resistance of 5Ω or more. No warranty can be made for correct
operation if a solenoid with a resistance of less than 5Ω is used.
If the presser foot is not held in place, set memory switches [37] and [38] to ON in memory
switch mode.
4. If using a pneumatic-type presser lifter device
∗ Change the power supply for the 6-pin plug. For the solenoid type, use (1) 40VDC, (4) SOL
output, and for the pneumatic type, use (3) 40VDC, (4) SOL output. (Change the power
supply between (1) and (3).)
∗ If the presser foot is not held in place, set memory switches [37] and [38] to ON in memory
switch mode.
∗ Use a 30VDC valve as the air valve. If you use a 24VDC type, add a 3W – 5W, 220Ω resistor
to the valve (to prevent overheating).
7. DIP switch functions and selecting a pulley
Note) Shaded areas indicate default settings. Other settings vary depending on destination and
sewing machine specifications.
Presser foot is lowered when treadle is returned to neutral position
ON
DIPSW1-1
DIPSW1-2
DIPSW1-3
DIPSW1-4
DIP switch 1-1 is set to ON for export specifications and to OFF for domestic specifications.
Selecting the motor pulley (DIP switch 1-2 setting)
Motor pulley diameter (Three standard types: Ø80, Ø90 and Ø105)
Check that the motor pulley diameter matches the setting for DIP switch 1-2.
Note) For a single needle machine head with a maximum sewing speed of 4700 rpm or less, use a
Ø90 pulley.
For a single needle machine head with a maximum sewing speed of 4800 rpm or more, use
a Ø105 pulley.
For chain stitch sewing machines and overlock sewing machines, use a Ø105 pulley.
For the B891 series of unison feed sewing machines for heavy material, use a Ø80 pulley.
(If the machine head type is set to B891 in machine head setting mode, the pulley diameter
will be set automatically to Ø80. Therefore, make sure that DIP switch 1-2 is set to ON.)
immediately after thread trimming. (Export specifications)
Presser foot is raised and knee switch has priority when treadle is returned to
OFF
neutral position immediately after thread trimming. (Domestic specifications)
Motor pulley diameter Ø90 (except B891/B892/B894)
ON
Motor pulley diameter Ø80 (for B891/B892/B894 machine head)
Motor pulley diameter Ø105 (except B891/B892/B894)
OFF
Motor pulley diameter Ø90 (for B891/B892/B894 machine head)
Automatic presser lifter device used (with delay time)
ON
OFF Automatic presser lifter device not used
Treadle depression to forward 2nd step (default 1st). Forward depression
ON
voltage ON 2.5V
OFF Treadle depression to forward 1st step. Forward depression ON voltage 2.0V
– 5 –
8. Using the box built-in panel
1. Part names and panel key functions
When the power switch is turned ON, the display will appear as shown in the illustration.
∗ 1 to 4 are displayed in the pattern display section.
∗ The icon function (ON/OFF) state, number of tacking stitches (A, B, C, D), the number of set
length stitches (E, F) and the stitching speed are displayed at the ABCD display section.
In normal mode, the following operations are then possible.
] is displayed on the pattern's 7-segment display, or a [ ] at the [ABCD] 7-segment's lower
If [
line, the mode is OFF.
(1) Needle UP/DOWN key
The A [△] key can be used to switch the needle stop position to UP or DOWN.
When is displayed : OFF (needle stops in DOWN position when
treadle is at neutral)
When is displayed : ON (needle stops in UP position when treadle
is at neutral)
(2) Correction key
The B [△] key can be used to turn correction sewing ON or OFF.
Set to ON if you would like to use the actuator switch for correction sewing
when the sewing machine is stopped. Correction sewing (low speed) can
then be carried out. This cannot be used after thread trimming when the
needle stops in the UP position.
If the actuator switch is pressed while the sewing machine is operating,
reverse feed will be carried out.
Note: If using a covering sewing machine with the machine head type set to
B256 ("
trimming/wiping ON and OFF. When set to ON, top covering thread
trimming/wiping is enabled, and when set to OFF, it is disabled.
∗"), this key can be used to turn top covering thread
(3) Slow start key
The C [△] key can be used to turn the slow start ON or OFF.
Set to ON if you would like the slow start to be used at the sewing start (after
thread trimming and needle UP stop).
(The first two stitches are sewn at slow speed.)
(4) Presser lifter key
The D [△] key can be used to raise and lower the presser lifter (ON/OFF).
Set to ON if you would like the presser lifter to be raised when the sewing
machine stops. When set to ON, the presser foot is always raised when the
sewing machine is stopped. This includes when the power is first turned ON,
when the sewing machine stops in the needle DOWN position, after thread
trimming is completed and when the sewing machine stops in the needle UP
position.
∗ This function operates in the same way as the knee switch (shorting/
opening the 1-pin plug of the presser foot 6-pin connector).
Changing the panel display mode
(5) Using the function (FUNC) key
When the FUNC key is pressed, the LEDs are turned ON and OFF in the
FUNC
following sequence: Sewing speed LED ON, ABCD (tacking number) LED
ON, EF (fixed length number) LED ON, all LEDs OFF.
– 6 –
(6) Sewing speed display mode
Press the FUNC key so that the sewing speed LED is ON.
The current setting value for the sewing speed appears in the "ABCD"
display.
The A [△] key can be used to set the thousands digit, and the B [△] key can
be used to set the hundreds digit.
(The setting range is within the inching speed setting and the maximum
sewing speed limit.)
(7) Backtack stitch number display mode
Press the FUNC key again to turn the sewing speed LED OFF and the
ABCD
ABCD LED ON. If the start tacking, end tacking or continuous tacking LED is
ON, the number of stitches set for that tacking will appear in the "ABCD"
display.
Press the A [△] key to set the number in the A column. Press the B [△] key
to set the number in the B column. Press the C [△] key to set the number in
the C column. Press the D [△] key to set the number in the D column. Each
column can be set to a number between 0 and 9. When 9 is reached and the
[△] key is pressed again, the setting returns to 0.
(8) Fixed length stitch number display mode
For patterns 2 to 4, press the FUNC key again to turn the ABCD LED OFF
EF
and the EF LED ON. The number of stitches set for F will appear in the AB
columns, and the number of stitches set for E will appear in the CD columns.
Backtack display mode and key operations
(9) Start tacking key
When the start tacking key is pressed, the LED turns ON. The number of
start tacking stitches which has been set (0 to 9) will appear in the AB
columns.
Note: If using a covering sewing machine with the machine head type set
to B256 ("
∗"), this key will turn start condense stitch sewing ON
and OFF. The number of start condense stitches which has been set
(0 to 99) will appear in the AB columns.
(10) End tacking key
When the end tacking key is pressed, the LED turns ON. The number of end
tacking stitches which has been set (0 to 9) will appear in the CD columns.
(End tacking can be canceled before it is completed.)
Note: If using a covering sewing machine with the machine head type set
to B256 ("
∗"), this key will turn end condense stitch sewing ON
and OFF. The number of end condense stitches which has been set
(0 to 99) will appear in the CD columns.
(11) Continuous tacking key
When the continuous tacking key is pressed, the LED turns ON. The number
of continuous tacking stitches which has been set (0 to 9) will appear in the
ABCD columns. After each cycle has been completed, the thread is trimmed
automatically.
∗ (9) to (11) are not available with the B776/SBL.
– 7 –
Pattern display mode and key operation
(12) Pattern setting and key operation
The sewing pattern can be set from 1 to 4. The pattern number increases by
1 each time the pattern key is pressed.
Manual mode
Fixed length sewing mode
Label attaching mode
Pleat sewing mode
∗ Patterns (2) to (4) are not available with the B776/SBL.
Accepting settings
(13) Using the SET key
This key is used to accept settings and to end the setting procedure in
SET
machine head setting mode, memory switch mode, parameter mode and
initialization mode.
It can also be used to accept settings and to end the setting procedure in
input/output setting mode and special mode.
– 8 –
2. Using the machine head setting mode
This product is shipped with the general specifications, so the machine head model is not set.
Thus, the machine head model must be set during setup.
Check the sewing machine model, and set the head with the following procedures.
Turn the power switch ON.
Is the built-in panel's power lamp (green) ON?
Is "
The motor will not start even if the treadle is pressed in this state.
Call out and set the sewing machine model name in this state.
Setting the machine head
"
" flashing at the built-in panel's A, B, C, D digits?
" : Machine head type has not been set.
" : Machine head is DB2-B737-3.
" : Machine head is LT2-B842-3.
" : Machine head is an SBL overlock.
Press the B [△] key to show the next type.
Press the C [△] key to show the previous type.
D [△] keyD [△] keyD [△] key
B [△] key
C [△] key
D [△] keyD [△] keyD [△] key
B [△] key
C [△] key
B [△] key
Note) Set the machine head type in machine head setting mode.
Use the B [△] key to increment the setting, and the C [△] key to decrement the setting.
Press the D [△] key to set the sub-class.
Press the SET key to accept the setting. Machine head setting mode will then be
exited.
Refer to "Machine head setting mode list" for the machine head types.
Press the
SET
key to
complete the
setting.
Sewing mode
– 9 –
Checking, setting and changing the machine head
Display No. "
Display No. "
Display No. "
+ Power switch ON
D [△] keyD [△] keyD [△] key
B [△] key (Increment)
C [△] key (Decrement)
" : Machine head is DB2-B737-3.
" : Machine head is DB2-B842-3.
" : Machine head is an SBL overlock.
B [△] key
C [△] key
B [△] key
Sewing mode
Note) Set the machine head type in machine head setting mode.
Use the B [△] and C [△] keys to set the name, and use the D [△] key to select the
sub-class.
Press the SET key to accept the setting. Machine head setting mode will then be
exited.
∗ Refer to "Machine head setting mode list" on page 11 for the machine head types.
Press the
SET
key to
complete the
setting.
– 10 –
Machine head setting mode list
This table shows the machine head names, maximum sewing speeds and motor pulley diameters.
(1) Factory default setting (no machine head setting)