Brother DB2-797 User manual

SERVICE MANUAL
FOR
082-8797
082-8798
SINGLE NEEDLE ADJUSTABLE TOP AND
BOTTOM FEED LOCK STITCH MACHNE
. .
~ ·
'
From the library of: Superior Sewing Machine & Supply LLC

CONTENTS
I SPECIFICATIONS,........................................................ 1
I MECHANICAL DESCRIPTIONS I·. ..........................................3
II) Uppershaftand needle bar mechanism . . . . . . . . . . . . . .. . . . . . . . . . . . 3
IZ]Lowershaftand rotary hook mechanism . . . . . . . . . . . . . . . . . . . . . . . . . 4
~Upper feed mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . •. 5
II] Presser foot mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . 6
I STANDARD ADJUSTMENT I·.............................................. 7
IIJAdjusting feed timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
IZ]Adjusting timing between needle and rotary hook . . . . . . . . . . . . . . . . 7
~Adjusting presser foot height . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 8
IIJAdjusting feed dog height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
rn:JAdjusting feeding foot and presser foot . . . . . . . . . . . . . . . . . . . . . . .. . . 9
<Alternative up and down movement of feeding and presser foot> 9
<Feeding
foot and presser foot height> . 0 0. 0 •••••••• 0 •• 0. 0 0... 9
<Adjusting feeding foot front and rear position> 0 ••• 0 ••••• 0... 9
<Adjusting feeding foot feed> .... 0 •••• 0 0 •••••• 0 ••• 0 ••••• 0 • • • • 9
II)Synchronizer {082-8798) . . . . . . •. •. . . . . . . . . . . . . . . . . . . •. . . •. . . . . • 10
[l]Replacing fixed and movable knives
{082-8798) . . . . . . . . . . . . •. . . . . 11
'OTHER, ....... .- ....................................................... 12
[!]Sewing with syntheticthread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 12
IZ1Sewing with vinylon thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 12
~Attaching presser foot lifter set . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . 13
IIJAttaching material end sensor . . . . . . . . . . . . . . . . . . . •. . . •. . . . . . . . . . 14
From the library of: Superior Sewing Machine & Supply LLC

I SPECIFICATIONS I
[B 797]
Optionsare as follows.
Operation panel
E- 20
E- 40
E-20
0
E - 40
0
E- 100
-1 -
[B798]
Production coun te r
@
brother
EJ
P.COUNTER
Material end sensor
SENSORll
Us e one of the operation panels and
the se n so r t ogether .
From the library of: Superior Sewing Machine & Supply LLC

DB2-B797 DB2-B798
Application Thick material Thick material
Sewing speed 2000spm 2000spm
Sewing length
0-Smm
0-9mm
Height of presser foot
14mm 15mm
(knee lifter)
Height of presser foot
7.5mm Smm
(presser bar lifter lever)
Rotary hook Double sized Double sized
Lubrication Manual lubrication Manual lubrication
Needle DPx 17#23 (39mm)
DPx 17#23
Weight of machine head 30kg 30kg
Thread take-upstroke 73mm 73mm
Needle barstroke 34mm 38mm
Presser foot stroke 4.5mm 4.5mm
Feeding
foot stroke 2-4.5mm 2.2-4mm
Height of feed dog 1.2mm 1.2mm
Durability • Thread take-up and needle • Thread take-up and needle
barcrank have bearings. barcrank do not have
bearings.
• Upperfeed rock lever
uses
• Upperfeed rock lever
uses
stud screws. taper threads.
-2-
From the library of: Superior Sewing Machine & Supply LLC

IMECHANICAL DESCRIPTIONS!
[II Upper shaft and needle bar mechanism
1) When the pulley0 rotates in the direction ofthe arrow, the upper shaft@ rotates.
2) The upper shaft@ then rotates the counter weight@.
3) The counter weight@ in turn rotates the attached needle barcrank e.
4) The needle barcrank e then rotates the thread take- up lever 0.
5) The thread take-up lever 0 moves the needle bar f), attached to the needle barclamp 0, up and down.
6) The needle bar f) is guided by the needle bar bushings, (U) @ and (D) @.
- 3-
From the library of: Superior Sewing Machine & Supply LLC

~ lower shaft and rotary hook mechanism
1) When the pulley 0 rotates in the direction of the arrow, the upper shaft gear @ attached to the upper
shaft@ also rotates .
2) The upper shaft gear@ rotates the vertical sha ft gear (U) 0 attached to the top of the vertical shaft e.
3) The vertical sha ft gear (U) 0 then rotates the vertical shaft gear (D) @ attached to the end of the
vertical shaft e.
4) The vertical shaft gear (D)@ in turn rotates the lower shaft gear f).
5) The lower shaft gear f) then r otates the lower shaft@.
6) The l ower shaft@ rotates the rotary hook@.
-4-
From the library of: Superior Sewing Machine & Supply LLC

@] Upper feed mechanism
<Up and down movement>
1) When the pulley0 rotates in the direction of the arrow, the upper shaft@ rotates.
2) The upper shaft@ rotates the upperfeed li fting eccentric wheel@.
3) The upperfeed lifting eccentric wheel@ then rotates the attached upper lift ing feed connector0 .
4) The upper lifting feed connector 0 pivots the upper feed lifting rock arm (R) 0.
5) The upperfeed lifting rock arm (R) 0 then pivots the upperfeed lifting rock shaft@.
6) The upperfeed lifting rock shaft@ in turn pivots the upperfeed lifting rock arm f).
7) The upperfeed lifting rock arm f) moves the link (L)@ back and forth.
8) The link {L)@ moves the upper feed lifting lever@ up and down.
9) The upper feed lifting lever @ transmits an up-and-down movement to the attached feeding foot
connector®.
10) The feeding foot connector® moves the feeding foot ID up and down.
<Back and forth movement>
1) When the pulley 0 rotates in the direction ofthe arrow, the upper shaft@ rotates.
2) The upper shaft@ moves the feed cam sleeve@ up and down.
3) The feed cam sleeve@ moves the feed forked connector ill up and do wn.
4) The feed forked connector ill pivots the feed rock shaft arm ill.
5) The feed rock shaft arm ill then pivots the feed rock shaft @.
6) The feed rock shaft @ in turn pivots the feed rock shaftarm ®.
7) The feed rock shaft arm® moves the upperfeed rock connector {L) (f) up and down.
8) The upperfeed rock connector {L) (f) pivots the upper feed rock arm {R) ®.
9) The upperfeed rock arm (R) ®then pivots the point of the upper feed rock shaft assembly®.
1 0) The upper feed rock shaft assembly® pivots the roller stud assembly@.
11) The roller stud assembly@ then pivots the upperfeed rock lever@.
12) The upperfeed rock lev er@ moves the lin k {S)@ back and forth.
13) The link (S)@ then moves the feeding foot connector bracket a> back and forth.
14) The feeding foot connector bracket a> then transmits this back-and-f orth movement to the feeding
foot connector®.
15) The feeding foot connector® moves the feeding foot ID back and forth.
-5-
From the library of: Superior Sewing Machine & Supply LLC

[!] Presser foot mechanism
1) When the pulley 0 rotates in the direction of the arrow, it ro tat es the upper shaft@.
2) The upper shaft@ rotatesthe upper feed lifting eccentric wheel@.
3) The upp er feed lifting eccentric wheel@ then rotates the attached upper lifting feed connectore.
4) The upper liftin g feed connectore pivots the upper feed lifting rock arm (R) 0.
5) The upper feed lifting rock arm (R) 0 then pivots the upperfeed lifting rock shaft@ .
6) The upper feed lifting rock shaft@ in turn pivots the upper feed li fting rock arm f).
7) Th e upper feed lifting rock arm f) moves the link (L)@back and forth.
8) The link (L)@ then moves the upper feed lifting lever@ back and forth.
9) The upper feed lifting lever@ in turn moves the presser foot bar bracket® back and forth.
10) The presser foot bar bracket® then transmits this back-and- forth movement to the presser bar ID.
11) The presser bar ID moves the presser foot @ up and down .
- 6-
From the library of: Superior Sewing Machine & Supply LLC

I STANDARD ADJUSTMENT I
lil Adjusting feed timing
penetration
4 ........ 6 mm
1. Smm
5. Smm
1) Turn the pulley to make thefeed dog even with the needle plate top surface.
2) Loosen the screw and detach the rear plate.
3) Loosen the two screws 0. Adjust the needle penetration to 4-6mm shown in the figure above by
turningthe feed
cam @ in the direction of the arrow.
~ Adjusting timing between needle and rotary hook
<Needle bar rise>
I0. I mm
or less
-7-
Rotate the pulley toward yourself and align the
rotary hook point 0 with needle center @ when
the needle
is raised 2.2 mm from its lowestposition.
• Loosen the screw @). Align the rotary hook
point0
with the needle center@.
•
At this time, secure the rotary hook 0 so that
the gap between the rotary hook point 0 and
the needle@
is less than 0.1 mm.
NOTE: When using
vi nylonthread, see P.12.
From the library of: Superior Sewing Machine & Supply LLC

<Needle bar height>
0.5--l.Smm
~ Adjusting presser foot height
[!] Adjusting feed dog height
-8-
Adjust the gap between the top of the needle eye
and rotary hook point 0 to 0.5-1.5 mm when the
rotary hook
point 0 is aligned with the needle
center@.
•
Loosen the screw @). Move the needle bar 0
up and down to adjust the gap.
The standard presser 0 rise is 7.5 mm when it is
raised using the presser foot lifter@.
1) Loosen the presser adjusting screw @) and raise
the presser foot 0 using the presser foot lifter
@.
2) Put a 7.5 mm gauge or something similar under
the presser
foot 0.
3) Loosen the screw 0 and move the presser foot
0 up and down to adjust.
The standard feed dog 0 height from the needle
plate
top surface is 1.2 mm when the stitch length is
at its maximum.
• Loosen the screw@. Move the feed ·lifting arm
@) up and down to adjust.
From the library of: Superior Sewing Machine & Supply LLC

~ Adjusting feeding foot and presser foot
<Alternative upand down movement of feeding and presser foot>
JMJ'l
left
-------=-==--
same height
<Feeding foot and presser foot height>
2-4.5mm
<Adjusting feeding foot front and rear position>
<Adjusting feeding foot feed>
-9-
The feeding foot 0 and presser foot @ move up
and down alternately.
The feeding foot 0 height position should be
equal or slightly lower than
the presser foot @
highest position.
1) Lower the presser foot lifter @) while the
thread take-up
is at its highest position.
2) Loosen the screw 0 .Move the upper feed
lifting rock arm 0 right and left.
When moved
right . . . . Presser foot rises even
to the feeding foot.
When moved
left .. . . . Presser foot descends.
The standard heightrange is 2-4.5 mm.
• Loosen the nut @) and adjust the heights
appropriate
to the material by moving the
upper lifting feed connector shaft 6 up and
down.
Maximum height . . . . . 4.5 mm
Minimum height . . . . . 2 mm
The feeding foot 0 end should be aligned with the
feed dog@ end.
• Loosen the screw @). Turn the upper feed rock
shaftassembly«!)
to adjust.
The feeding foot @ feed should be equal to the
feed dog 0 feed.
• The feeding foot feed can be changed to suit
conditions.
• Loosen the nut Q). Move the roller stud 4D up
and down
to adjust it.
From the library of: Superior Sewing Machine & Supply LLC

[§] Synchronizer (082-8798)
21--23mm
.The synchronizer detects the needle with two hole
ICs. Also,the synchronizer controls needle lowest
position signal and thread trimming signal with
one hole IC.
The distance between the needle plate top surface
and screw bottom should
be 21-23 mm whenthe
needle is at its lowestposition. Also,the distance
between the needle plate
top surface and the
needle tip is 12-13 mm when the machine is
stopped at the needle highestposition.
Be sure to turn off the powerwhen adjusting.
<Adjusting needlethread trimming signal sensor position>
<Adjusting needle highest position>
1) Turn the pulley in the direction of the
operation to raise the needle bar 0 7.5 mm
from its lowestposition.
2) If the hole IC@ is not aligned with the magnet
@ bottom, loosen thescrew e and move the
hole IC@ to adjust it.
NOTE: Movethe hole IC@ in the direction of the
operation
to raise the needle bar0 highest
position.
Movethe hole
IC@ in the opposite
direction
to lowerit.
• Loosen thescrew@ to move the hole IC@ and adjust it.
NOTE: Move the hole IC €) in the direction of theoperation to lowerthe needle bar0 highest position.
Move
the hole IC@ in the opposite direction to raise it.
-10-
From the library of: Superior Sewing Machine & Supply LLC

(1] Replacing fixed and movable knives (082-8798)
Be sure to turn off the powerwhen replacement.
<Replacingfixed
knife>
<Replacing movable knife>
lower thread
finger
fig. A
1) Tiltthe sewing machine head.
2) Remove the screw 0, and remove the bobbin
case holderposition bracket @.
3) Remove the screw @) then remove the fixed
knife0.
NOTE: If the fixed knife 0 has lost itssharpness, use
an oil stone to sharpen it, as shown in Fig.A.
1) Raise the presser foot by using the presser foot
lever.
2) Remove the screws @) then remove the needle
plate@>.
3) Turn the sewing machine pulley until the needle
bar reached its highest position.
4) Press the thread cutter connecting rod 6
manually in the direction of the arrow until
position at which the screws @) can be seen is
reached then stop.
5) Remove the screws @) and then remove the
movable knife @).
NOTE: When removing the needle plate @)and the
movable knife @), be sure to first remove the
needle.
NOTE: Reassembly can be performed by simply
reversing the above procedure.
-11-
From the library of: Superior Sewing Machine & Supply LLC

!OTHER I
[]] Sewing with synthetic thread
When sewing with synthetic thread, thread as inthe figure below.
[082- 8797]
~ Sewing with vinylon thread
2.8-3.0mm
-12-
[082- 8798]
When sewing
with vinylon thread, turn the
machine pulley towards you so that the rotary
hook
point 0 is aligned with the center of the
needle @ when the needle
is raised 2.8- 3.0
mm above its lowestposition.
From the library of: Superior Sewing Machine & Supply LLC

@1 Attaching presser foot lifter set
Attach the presser foot lifter set to the underside of the table as shown in the figure below.
<Measuremen~s, top view>
machine
58mm
46mm
62mm
107mm
table edge
<The underside of the table>
-13-
From the library of: Superior Sewing Machine & Supply LLC

[!] Attaching material end sensor
:>.<: Make sure the power is off when attaching the material end sensor.
D
sensor
SE NSORU
Put the reflect ion plate direct ly under the sensor.
1) Change the posi tion of the operat ion panel as
shown in the figure on the l eft.
2) Remove the rubber cap on the side of the
operation panel.
Plug
the connectorof the sensor into the panel.
3) Be careful not to catch the flat cable of the
connector and attach the sensor II with the
two screws.
<Thread ing the cord>
- 14-
From the library of: Superior Sewing Machine & Supply LLC

...
.;
.;
.-,.:·
...
BROTHER INDUSTRIES, LTD.
HEAD OFFICE: No. 35, 9-CHOME,
HORITA-OORI, MIZUHO-KU, NAGOYA, JAPAN 467
CABLE: BROTHER NAGOYA,
TELEX: 4473696 BROS J
1990.01. Printed in Japan I 0010418H
From the library of: Superior Sewing Machine & Supply LLC