Makita M0900B Operating instructions

M0900B
REPAIR MANUAL
Angle Grinder
OFFICIAL USE
For ASC

4x18 Tapping screw
P 2/ 13
Repair
CAUTION: Repair the machine in accordance with “Instruction manual” or “Safety instructions”.
[1] NECESSARY REPAIR TOOLS
[2] LUBRICANT AND ADHESIVE APPLICATION
[3] DISASSEMBLY/ASSEMBLY
[3]-1. Armature, Spiral Bevel Gear 13, Ball Bearing 629ZZ, Ball Bearing 607ZZ
Code No. Description Use for
1R005 Retaining Ring Pliers RT-2N
Retaining Ring S & R Pliers
removing/ mounting Retaining ring R-32
1R026 Bearing Setting Pipe 16-8.2 removing Spindle from Spiral bevel gear 37
1R217 Ring 22 removing Spindle from Spiral bevel gear 37
1R268 Spring Pin Extractor 3 disassembling Shaft lock mechanism
1R269 Bearing Extractor removing Ball bearing 629ZZ/ 607ZZ
1R291 removing Retaining ring S-12
1R281 Round Bar for Arbor 7-50 removing Spindle from Spiral bevel gear 37
removing Switch knob from Switch lever
Apply the following lubricants to protect parts and product from unusual abrasion. (Fig. 1)
DISASSEMBLING
(1) Remove Rear cover, then disconnect Carbon brush from Armature’s commutator. (Fig. 2)
Fig. 2
4x22 Tapping screw (4 pcs.)
Rear cover
Armature
Gear housing complete
1. Remove Rear cover by unscrewing one
4x18 Tapping screw.
2. Remove the end of Spiral spring from Carbon brush,
then pull out Carbon brush half way.
No need to remove Carbon brush completely.
3. Unscrew four 4x22 Tapping screws,
then separate Gear housing complete
together with Armature from Motor housing.
Motor housing
Spiral spring
Item No. Description Lubricant AmountPortion to lubricate
LUBRICANT
Fig. 1 : Makita grease FA No.2 (10g)
Gear Housing Complete Gear room Makita grease FA No.2 10g
14
14
O Ring 26 Whole portion Makita grease FA No.2 a little-

P 3/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[[3]-1. Armature, Spiral Bevel Gear 13, Ball Bearing 629ZZ, Ball Bearing 607ZZ
DISASSEMBLING
ASSEMBLING
M6 Hex nut
Ball bearing
629ZZ
Ball bearing
607ZZ
Flat washer 9
Wrench 10 Spiral bevel gear 13
4. Disassemble Armature from
Gear housing complete. 5. Disassemble Spiral bevel gear 13 from Armature by removing M6 Hex nut with Wrench 10.
(2) Remove Spiral bevel gear 13, Ball bearings from Armature. (Fig. 3)
Do the reverse of the disassembling steps.
Note in Assembling:
When Motor housing and Gear housing complete are joined together,
Spindle must be positioned on the opposite side of Switch knob. (Fig. 4)
6. Using 1R269, remove Ball bearing 629ZZ and Flat washer 9 from the Fan side, then Ball bearing 607ZZ
from Commutator end.
Armature
Fig. 3
Fig. 4
Gear housing
complete
Motor housing
Spindle
Switch knob
M6 Hex nut
Ball bearing
607ZZ
Ball bearing
629ZZ
[Wrong][Correct]
Switch knob
Spindle

P 4/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[3]-2. Field
DISASSEMBLING
ASSEMBLING
2. Drive two 4x22 Tapping screws in holes in two diagonal corners.
Then remove Field from Motor housing by alternately tapping
the screw heads.
Note: Do not tap the end surface of Motor housing directly
because its inlaid portion is rather fragile.
1. Disconnect the receptacles from
Brush holders, Terminal block
and Switch. (Refer to Fig. D-1.)
Remove two 4x60 Tapping screws
that secure Field in Motor housing.
Fig. 5
Fig. 6
4x22 Tapping screw
M4x16
Pan head screw
Bearing box
1. Unscrew four M4x16 Pan head screws, then separate
Bearing box from Gear housing complete.
(1) Separate gear housing complete together with Armature as illustrated in Fig. 2.
(2) Remove Filed from Motor housing. (Fig. 5)
(1) Disassemble Bearing box from Gear housing complete, then remove Retaining ring S-12 from Spindle. Fig. 6
Note in Assembling:
Field must be mounted to Motor housing so that its Lead wires can be routed out through the openings of Motor housing
as described in Fig. D-2.
[3]-3. Spiral Bevel Gear 37, Ball Bearing 6201DDW
4x60 Tapping screw
2. Remove Retaining ring S-12 with 1R291.
Retaining ring S-12
1R291

P 5/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[3]-3. Spiral Bevel Gear 37, Ball Bearing 6201DDW
DISASSEMBLING
Fig. 7
1R026
1R281
1R217
approx.
10 mm
(2) Disassemble Spindle as illustrated in Fig. 7.
(3) Disassemble Ball bearing 6201DDW from Gear housing complete. (Fig. 8)
Bearing box
Spindle
Spiral bevel
gear 37
4. Push Spindle out a little by striking 1R026
carefully using arbor press with a down stroke
of approx.10mm long. Then remove 1R026.
3. Put Bearing box on 1R217,
then put 1R026 over the
stepped portion of Spindle.
Spindle
Fig. 8
1R005
6. Remove Retaining ring R-32 with 1R005. 7. Remove Ball bearing 6201DDW from
Bearing box.
In this step, Flat washer 12 is removed.
Ball bearing
6201DDW
Flat washer 12
Retaining
ring R-32
5. Put 1R281 on Spindle.
Then, using arbor press,
press 1R281 to remove
Spindle from Spiral bevel
gear 37.
Note:
Do not reuse removed Ball bearing 6201DDW
because it is damaged in this step.

P 6/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[3]-3. Spiral Bevel Gear 37, Ball Bearing 6201DDW
ASSEMBLING
Fig. 9
1R028
Ball bearing
6201DDW
Flat washer 12
Spindle
1R217
1. Mount Flat washer 12
on Spindle. 2. Set Spindle on 1R217, then set Ball bearing 6201DDW and
1R028 as drawn below.
Then press-fit the Ball bearing
on Spindle by pressing 1R028
with arbor press.
Bearing box
1R005
Ball bearing 6201DDW and Spiral bevel gear can be assembled as described in Fig. 9.
1R028
4. Install Retaining ring R-32 with 1R005
to secure Ball bearing 6201DDW.
Retaining ring
R-32
Spiral bevel
gear 37
6. Install Retaining ring S-12 with 1R291.
Spindle
3. Set Bearing box on 1R217,
then set 1R028 on Spindle
as drawn below.
Then press-fit Spindle into
Bearing box by pressing 1R028
with arbor press.
1R028
Bearing box
Spindle
Important:
Apply lubricant to
this portion of Spindle
for smooth press-fitting
of Spiral bevel gear 37.
5. Set Bearing box on 1R217, then set 1R028 on Spiral bevel
gear 37 as drawn below.
Then, keeping Spiral bevel gear 37 in parallel with 1R217,
press-fit the Gear on Spindle of Bearing box by pressing
1R028 with arbor press.
1R217
Bearing box

P 7/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[3]-4. Switch Lever
DISASSEMBLING
ASSEMBLING
Fig. 10
Fig. 11
1. Slide Switch knob to OFF position,
then insert 1R281 between Switch knob
and Motor housing to lock Switch knob
in the position.
2. Push Switch lever back towards ON position
to disconnect Switch knob from Switch lever.
3. Switch knob can now be removed. 4. Pull out Switch lever from Motor housing
while bending it to release the link from
the toggle of Switch.
(1) Remove Rear cover. (Fig. 2)
(2) Switch lever can now be disassembled as described in Fig. 10.
toggle of Switch
Switch knob Switch lever
Switch Knob and Switch lever can be mounted in place as described in Fig. 11.
Switch knob
1R281
Motor housing
Switch knob
Switch lever
1. Insert Switch lever into Motor housing
until the square loop of Switch lever’s
front end is seen through the Switch knob
hole of Motor housing, and keep the loop
in the position. 2. Engage the hook of Switch Knob through Motor housing
in the square loop of Switch lever’s front end.
Hook of
Switch knob
Square loop of
Switch lever’s front end

P 8/ 13
Repair
[3] DISASSEMBLY/ASSEMBLY
[3]-5. Shaft Lock
DISASSEMBLING
(1) Separate Gear housing complete and Armature from Motor housing. (Fig. 2)
(2) Pull offArmature from Gear housing complete. (Fig. 3)
(3) Remove Bearing box by unscrewing four M4x16 Pan head screws. (Fig. 6)
(4) Disassemble Shaft lock mechanism as described in Fig. 12.
1. Put gear housing complete on 1R258.
Then remove Shoulder pin 4 from Gear housing complete
by inserting 1R268 through the small hole of Pin cap onto
Shoulder pin 4 and then tapping 1R268 with hammer.
2. Slowly remove 1R268 from Pin cap.
Be careful not to lose Compression spring 8
as the compressed spring may fly away.
Shoulder pin 4
Pin cap
Compression
spring 8
Fig. 12
1R268
1R258
Pin cap
plastic dust
Shoulder pin 4
ASSEMBLING
Assemble Shaft lock. (Fig. 13)
Then do the reverse of the disassembling steps.
Fig. 13
3. Assemble Compression spring 8
and new Pin cap by pressing them
to Shoulder pin 4.
2. Insert Shoulder pin 4 through
the hole of Gear housing complete.
Pin cap
Compression
spring 8
Shoulder
pin 4
Note: Do not reuse removed Pin cap.
1. Remove from Shoulder pin 4
all the plastic dust produced
in the disassembling process.
Note: Do not reuse the Pin cap removed
from Gear housing complete
because the inside surface of Pin cap
is damaged by Shoulder pin 4
when it is removed.

Circuit diagram
P 9/ 13
Fig. D-1
White
Red
Blue
Brown
Field,
viewed from
Rear cover side
Power supply cord
Noise suppressor
(not used for some
countries)
Terminal block
(Closed end splice
is used for some
countries instead
of Terminal block.)
Brush holder A
Brush holder B
Switch
Color index of lead wires' sheath
Black
1
2
Insulated terminal (M4)
For countries where suppression of radio interference is required
Blue/White Brown/Black
20 AWG*
20 AWG*
*AWG: American Wire Gauge
18 AWG*
Magnet wire
Magnet wire
Magnet wire
Straight receptacle
(Without lock,
#110, t=0.8mm) Straight receptacle
(Without lock,
#110, t=0.8mm)
Circuit of Switch
12

Circuit diagram
P 10/ 13
Fig. D-2
White
Red
Blue
Brown
Field,
viewed from
Rear cover side
Power supply cord
Terminal block
(Closed end splice
is used for some
countries instead
of Terminal block.)
Brush holder A
Brush holder B
Switch
Color index of lead wires' sheath
Black
1
2
Insulated terminal (M4)
For countries where suppression of radio interference is not required
Blue/White Brown/Black
*AWG: American Wire Gauge
18 AWG*
Magnet wire
Magnet wire
Straight receptacle
(Without lock,
#110, t=0.8mm) Straight receptacle
(Without lock,
#110, t=0.8mm)
Circuit of Switch
12

P 11/ 13
square opening
for Switch knob
Field lead wire (white)
to Terminal block or
to Closed end splice
Field lead wire (black)
to Brush holder
Field lead wire (red)
to Switch
Field lead wire (black)
to Brush holder
Pass Field lead wires
through these openings.
Note:
The wires must be tight
in Motor housing.
Wiring of Field Lead Wires
Wiring diagram
Fig. D-3
Fig. D-4
Connect Insulated connectors of Lead wires
to Switch from the maktec logo side of
Motor housing.
Switch
Insulated terminal
Motor housing
Wiring to Switch
Motor housing viewed
from Rear cover side

Wiring diagram
P 12/ 13
Fig. D-5
Wiring on Motor Housing
Switch
rib (b)
rib (c)
rib (d)
rib (a)
Switch lever
Noise
suppressor
Terminal
block Terminal block
Left Side ViewBottom View
rib (a)
rib (b)
Switch
rib (b)
rib (c)
rib (d)
rib (a)
Switch lever
Noise
suppressor
Closed end
splice Closed end splice
rib (a)
rib (b)
Fix Field lead wire (red)
in these two grooves.
Fix Field lead wire (red)
in these two grooves.
Be sure to route all of the Lead wires inside of the ribs a) to d) as drawn below
to prevent the wires from being pinched between Motor housing and Rear cover.
Put Terminal block/ Closed-end splice in place as drawn below.
When Terminal block is used
When Closed end splice is used

Wiring diagram
P 13/ 13
Fig. D-6
boss
rib
rib (c)
rib (a)
Right Side View Top View
Wiring on Motor Housing
Put the slack portion of Lead wires
of Power supply cord in this place.
Noise
suppressor
Switch
lever
When fixing Lead wires in this Lead wire holder,
Field lead wire (white) must be put over Field lead
wire (black) and Noise suppressor’s Lead wire (white).
Route Noise suppressor’s
Lead wire (white) between
the boss and the rib.