Makita DUC256 Operating instructions

February 2020
Ver.1
OFFICIAL USE
For ASC
CORDLESS CHAIN SAW
250MM(10")/ 300MM(12")/
350MM(14")/ 400MM(16")
DUC256, DUC256C/ DUC306/
DUC356/ DUC406
REPAIR MANUAL

2 / 32
1CONTENTS
1CONTENTS.................................................................................................................................................................................2
2CAUTION....................................................................................................................................................................................3
3NECESSARYREPAIRING TOOLS...........................................................................................................................................3
4LUBRICANTANDADHESIVEAPPLICATION......................................................................................................................3
5TIGHTENING TORQUE SPECIFICATIONS............................................................................................................................4
6REPAIR........................................................................................................................................................................................5
6-1 Saw chain.............................................................................................................................................................................5
6-1-1 Disassembling.............................................................................................................................................................5
6-1-2 Assembling..................................................................................................................................................................5
6-2 Chain tension/ Chain Brake section.....................................................................................................................................7
6-2-1 Disassembling.............................................................................................................................................................7
6-2-2 Assembling................................................................................................................................................................10
6-3 Electric parts section..........................................................................................................................................................13
6-3-1 Disassembling...........................................................................................................................................................13
6-3-2 Assembling................................................................................................................................................................18
7CIRCUIT DIAGRAM................................................................................................................................................................23
8WIRING DIAGRAM.................................................................................................................................................................25
8-1 Stator section......................................................................................................................................................................25
8-2 Switch/ Controller section..................................................................................................................................................26
8-3 Main switch section ...........................................................................................................................................................27
8-4 Closed end splice section...................................................................................................................................................28
9TROUBLESHOOTING.............................................................................................................................................................29
9-1 Note for Repairing .............................................................................................................................................................29
9-2 Test for checking the short-circuit in FET (Field Effect Transistor) of controller..............................................................29
9-3 Flowchart for Troubleshooting...........................................................................................................................................31

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2CAUTION
Repair the machine in accordance with "Instruction manual" or "Safety instructions".
Follow the instructions described below in advance before repairing:
Wear gloves.
In order to avoid wrong reassembly, drawor write down where and how the parts are assembled, and what the parts are.
It is also recommended to have boxes ready to keep disassembled parts by group.
Handle the disassembled parts carefully. Clean and wash them properly.
Remove Batteries, exceptwhen theyare necessary to check the operation of the machine.
3NECESSARYREPAIRINGTOOLS
Code No.
Description
Use for
1R003
Retaining ring pliers ST-2N
assembling Compression spring 7
1R026
Pipe 8-16-50
press-fitting Ball bearing 696ZZ
1R030
Pipe 17-25-50
press-fitting Ballbearing 6000DDW
1R033
Ring 10-60-15
press-fitting Ball bearing 696ZZ
1R242
Round bar 13-100
removing Ball bearing 6000DDW
1R269
Bearing puller small
removing Ball bearing 696ZZ
1R311
Retaining ring pliers L
removing/ assembling Retaining ring R-26
1R411
Push bar for lead wires
fixing Lead wires
4LUBRICANTANDADHESIVEAPPLICATION
Description
Amount
Makita grease FANo.2
Apply a little unless specified in the figure.
Loctite 243 orThreeBond 1342 (H)
Fig. 1

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5TIGHTENINGTORQUE SPECIFICATIONS
Parts to fasten
Fastener
Q'ty
Tightening
torque
(N∙m)
Adhesion
Housing set ↔Guide plate L
M5x12 H. L. socket head bolt
1
4.0 - 6.0
*
Housing set ↔ Front handle
5x20 Tapping screw
2
1.5 - 2.0
Sprocket cover ass’y ↔ Nut cover
4x12 Tapping screw
1
0.8 - 1.0
*Apply the specified adhesive to M5x12 H. L. socket head (4LUBRICANTANDADHESIVEAPPLICATION).
For screws except above, see Repair basic manual, Chapter 2.

5 / 32
6REPAIR
6-1 Sawchain
6-1-1 Disassembling
Fig. 2
1Remove Batteries [1] (2 pcs).
2Loosen Flange nut complete [2], then remove
Sprocket cover ass’y [3].
Fig. 3
3Lift up Saw chain section [1] and remove it.
Note
Disassemble the machine after cleaning wood dust
etc. with a brush and an air duster.
Guide bar in all photos is not the actual one.
However, the removing/ assembling way is the
same.
6-1-2 Assembling
Fig. 4
1Remove Guide bar case, then fit Saw chain [3] to
the grooves of Guide bar [1] andSprocket 6 [2]
with care of the orientation in accordance with the
picture shown on Sprocket cover.
Tips
Pick up the top side of Guide bar [1] and swing the
rear side. Saw chain [3] can be fit into the groove of
Guide bar [1].
Adjust Drive gear [5] to put the hook of Tension
slide [4] into the lower hole of Guide bar [1].
[1]
[3]
[2]
[3]
[1]
[4]
[5]
[1]
[1]
[3]
[2]
[1]
[3]
[2]
[1]

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Fig. 5
2Assemble Sprocket cover ass’y [2] to Housing set
[1] and tighten Flange nut complete [3] lightly.
Fig. 6
3Adjust Drive gear [2] until Saw chain [3] fit tightly
to Guide bar [1] while lifting Guide bar [1].
Fig. 7
4Release the brake and use a screwdriver or the like
to check that the tension of Saw chain [1] is not
loose. If Saw chain does not fit securelyinto
Sprocket, it may loosen.And so, do tension
adjustment again.
5Assemble Guide bar case [3] in place and tighten
Flange nut complete [2].
Note
Tighten Flange nut [2] while pushing the top of Guide
bar case [3] to the workbench and lifting up the
machine body.
[1]
[3]
[2]
[3]
[1]
[3]
[1]
[2]
[2]
[3]
[1]

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6-2 Chain tension/Chain Brakesection
6-2-1 Disassembling
Fig. 8
1Pull Front hand guard complete [1] to release the
brake.
Tips
Brake drum cannot be removed unless the brake is
released and Brake band complete is widened.
The brake section and Motor section cannot be
disassembled unless Brake drum complete is
removed.
Fig. 9
2Remove the following parts fromHousing set [1].
Stop ring E-7 [2]
Sprocket 6 or Sprocket 9 [3]
O ring 10 [4]
Brake drum complete [5]
Fig. 10
3Push Front hand guard complete [1] forward to
activate the brake.
Note
The brake operation after removing Housing R cover
[5] maycause the damage, therefore, be sure to
activate the brake to stretch Compression spring 7
before removing Housing R cover [5].
4Remove M5x12 H. L. socket head bolt [3], then
remove Guide plate L [4] from Housing set [2].
[1]
[4]
[2]
[3]
[5]
[2]
[3]
[4]
[5]
[1]
[5]
[3]
[2]
[1]

8 / 32
Fig. 11
5Remove the following parts fromHousing set [1].
4x18 Tapping screws [2] (6 pcs)
Spike bumper [3]
Chain catcher [4]
Housing R cover [5]
Fig. 12
6Lift up and release Compression spring 7 [2] with a
slotted screwdriver [1].Also, it can be removed
with 1R311 in accordance with Fig. 13.
Tips
When Link plate complete [3] is fully bent, the spring
force is the weakest and therefor it is easy to remove.
Fig. 13
7Remove the following parts from Housing set [1]
with 1R311.
Drive gear [2]
Straight bevel gears 14 [3] (2 pcs)
Tension slide [4]
Adjust screw [5]
Grommet [6]
Compression spring 7 [7]
Link plate complete [8]
Brake band complete [9]
[1]
[7]
[9]
[8]
[6]
[4]
[2]
[4]
[2]
[3]
[7]
[5]
1R311
[1]
[2]
[3]
[3]
[5]
[4]
[1]
[2]

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Fig. 14
8Remove M4x12 Pan head screws [2] (2 pcs) from
Front hand guard complete [1], then remove Front
hand guard retainer [3].
Fig. 15
9Push Fronthand guard retainer [1] forward and
remove it while pulling it toward your side.
Note
Remove Compression springs 3 [2] and Hand guard
guide [3] while holding themso as not to pop out.
10 Remove Hand guard guide [3] and Compression
spring 3 [2] from Housing set [4].
[1]
[3]
[2]
[3]
[4]
[1]
[2]
[3]
[3]

10 / 32
6-2-2 Assembling
Fig. 16
1Assemble Fronthand guard complete [2] to
Housing set [1].
2Assemble Fronthand guard retainer [3] to Front
hand guard complete [2] with M4x12 Pan head
screws [4] (2 pcs).
Tips
Apply the specified grease to the sliding portion of
Front hand guard complete [2].
Fig. 17
3Assemble Hand guard guide [2] and Compression
spring 3 [3] to Housing set [1].
Tips
Push Compression spring 3 [3] to the bottomwith a
slotted screwdriver.
Apply the specified grease to the tip ofHand guard
guide [2].
[2]
[1]
[2]
[3]
[1]
[2]
[4]
[2]
[3]
[3]