Alpha Tool.Com.HK Limited Polisher WDP120 User Manual

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		PERIODIC
 
  WARNING!
Preventive	maintenance	preformed	by	unauthorized	personnel	may	result	in	mis-
placing	 of	 internal	 wires	 and/or	 components	 which	 voids	 the	 warranty	 and	 could	
cause	serious	hazards.		We 	recommend	that	tool	service	and	repairs	not	covered	
in	the	manual	be	preformed	by	an	Alpha
®	Repair	Center.
Periodic	maintenance	is	done	to	check	the	tool	and	to	minimize	down	time.		These	
checks	are	done	based	on	hours	of	operation	and	operating	conditions.		 Operating	
condition	can	vary	depending	on	the	work	surface	and	job	being	preformed.		 If	the	
tool	is	not	used	for	a	long	period	of	time	the	carbon	brushes	should	be	checked	and	
the	commutator	cleaned,	before	putting	the	tool	back	into	operation.
		BEARINGS	AND	GEARS
To 	minimize	your	tool’s	down	time	and	expensive	tool	repairs,	it	is	recommended	to	
send	the	tool	back	to	an	Alpha®	Repair	Center	after	about	300	to	400	hours	of	opera -
tion	or	every	second	carbon	brush	set	change.		 The	bearings	should	be	replaced	
and	the	gears	should	be	checked.		 If	your	tool	starts	to	sound	differently,	this	could	
be	an	indication	of	a	worn	bearing;	continuing	to	use	the	tool	in	this	condition	could	
result	in	over	heating	or	motor	failure.
		CARBON	BRUSH	REPLACEMENT	
Carbon	brushes	wear	out	over	time,	based	on	the	polisher	usage.	If	a	carbon	brush	
is	 worn	 out,	it	may	 cause	 the	motor	 to	malfunction	 or	fail	 to	run.	 Whenever	 the	length 	
of	the	carbon	brush	reaches	the	wear	limit,	replace	with	a	new	set.
NOTE	-	 To	maintain	even	wear,	both	
brushes	 should	 be	 replaced	 at	 the	
same	time.
The	carbon	brushes	in	this	polisher	
are	 located	 underneath	 the	Rear 	
Cover	 (Part	#	 210053)	 as	shown	 in	
Figure	21.
Carbon	brushes	are	located	under	the	rear	cover
Figure-21 
						

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 REAR	COVER	REMOVAL
1.	 Gently	 pull	 water	 tube	 away	 from	holder.
2.	 Release	the	tube	from	the	holder.
3.		 Unwrap	3	inches	of	the	coiled	 harness.
4.		 Remove	 the	2	screws	 from	the	valve 	
bracket.
Figure-22
Figure-23
Figure-24
Figure-25 
						

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5.	 Pull	the	valve	assembly	away	from	mount.
6.	 Remove	the	rear	case	screw.
7.		 Hold	 polisher	with	one	hand	 and	
pull 	the 	rear 	case	 straight 	back	 with	
the	other	hand.
NOTE:	 Do	 not		twist	 case	 in	 a	 side	 to	 side	motion	when	pulling	back.
8.	 Pull	 back	the	rear	 case	 until	the	
carbon	 brush	assembly	 is	exposed.
NOTE:	 Do	not	 pull	 rear	 case	 further	 back
from	this	point.
Figure-28
Figure-29
Figure-27
Figure-26 
						

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9.		 Lift	the 	spring 	from 	the 	
carbon	brush	and	place	on	
the	 side	 of	the	 brush	 holder.
10.	 Remove	 the	carbon	 brush	wire	spade	 connector	 from	the	terminal	 post	and	then 	
remove	the	carbon	brush.
Figure-31
Carbon	Brush
Carbon	Brush Holder
Carbon	Brush Wire
Spring
Figure-30
Figure-32
Spade 	Connector
Figure-33 
						

							11.	 You	can	also 	remove 	the 	carbon 	brush 	by 	
removing	 the	screw	 and	pulling	 the	holder 	
out	with	a	pair	of	needle	nose	pliers.
12.	 With	 the	 carbon	 brush	 holder	 removed,	 you	 can	check	and	clean	the	armature	commuta-
tor.		The	 commutator	 is	the	 contact	 points	that	
the 	carbon 	brushes	 ride	on	when	 the	motor 	is 	
running.
NOTE:  Each polisher has 2 carbon brushes located on opposite sides of  each other.  After the replacement of the two brushes, assemble the 
polisher by reversing disassembly procedure.
13.	 Check	the	carbon	brush	for	wear.		Replace	if	worn	down	to	a	1/4"	.
14.	 Blow	dust	off	of	the	spring	and	check	for	proper	tension.
15.	 Remove	 the	 old	 carbon	 and	 disconnect	 the	 wire	 terminal	 wire.		 If	 the	 inside	
of	the	holder	is	filled	with	dust,	clean	before	installing	the	new	carbon	brush.		
Upon	installation	of	the	new	carbon	brush,	make	sure	the	twisted	wire	is	in	the	
slot	and	behind	the	wire	terminals	on	holder	as	in	the	photo	above.
Figure-34
25
Figure-35
Old Carbon Brush
worn down to a quarter
of an inch (1/4”).
New Carbon Brush 
						

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16.	 The	commutator	should	be	clean	and	shiny;	if	it	is	dull	and	black,	you	can	clean	it	with	a	commutator	cleaning	stone.
17.	 To	 clean	the	commutator,	 press	the	commutator	 cleaning	stone	against	 the	com -
mutator	and	rotate	the	armature	by	turning	the	spindle	shaft	by	hand.		 Continue	
for	a	minute	or	until	commutator	is	clean	and	shiny.
18.	 Reconnect	the	power	wire,	ensuring	that	the	wire	path	is	correct.			Reinstall	the	 carbon	 brush	 holder	 into	 the	 slot	 on	 motor	 housing	 and	 slide	 in	 until	 the	 tab	
for	the	screw	hits	the	stop.		 Install	the	screw	using	light	pressure	to	prevent	it	
from	stripping.
19.	 After	 both	 carbon	 brushes	 have	 been	 replaced	 you	 can	 reassemble	 the	 rear	 cover.		 Make	 sure	 the	 power	 wires	 are	 in	 the	 tool	 to	 prevent	 pinching	 of	 the	
wires.
Figure-36 Figure-37
CleanDirty
Figure-38 
						

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ALPHA® WDP-120 SCHEMATIC 
Revised: 12/2013 
						

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ALPHA® WDP-120 GUARD SCHEMATIC
Optional AccessoryFlexible	Connector	Hose 
						

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ALPHA® WDP-120 GUARD SCHEMATIC
  DRAWING	NO. PART	NO. DESCRIPTIONQUANTITY
1 310025Output	Shaft	with	Nitriding	(5/8"-11) 1
2 210006Key	(3x10) 2
3 210001Screw	M4x14 4
4 210002Spring	Washer	M4 8
5 210003Plane	Washer	M4 4
6 310002Aluminum	Gear	Case	Cover 1
7 210010Ball	Bearing	6201 1
8 310003Bearing	Cover 1
9 310004Screw	M4x10 3
10 310005Gear	Washer 1
11 210016Gear 1
12 210017Wave	Spring	Lock	Washer	10 1
13 210018"C"	Clip	for	Shaft	10 1
14 210019Oil-impregnated	Bearing	8x12x8 2
16 210021Self-tapping	Screw	4.2x40 4
17 210022Case	Plastic	Cover 1
18 210023Screw	M10x20 2
19 210024C-Handle 1
22 210027Gear	Case 1
23 210028Anti-loose	Nut	M6 1
24 210029Pinion	Gear	Z3 1
25 210030Transmitting	Shaft 1
26 210031Ball	Bearing	6200 1
27 210032Bebel	Gear	Z2 1
28 210033Screw	M4x8 2
29 210034Bearing	Retainer 1
30 210035O-Ring	21.2x1.8 1
31 210036Ball	Bearing	608 1
32 210102Armature	120V 1
33 210095Magnetic	Ring 1
34 210038Ball	Bearing	607 1
35 210039Rubber	Bearing	Seat 1
36 210106Windshield 1
37 210041Self-tapping	Screw	4.2x70 2
ALPHA® WDP-120 PARTS LIST 
						

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ALPHA® WDP-120 PARTS LIST 
DRAWING	NO. PART	NO. DESCRIPTIONQUANTITY
38 210042Field	Coil	120V 1
39 310015Brand	Label 1
40 210091Field	Coil	Case 1
41 310006Data	Label 1
42 210046Carbon	Brush	Holder 2
43 210047Coil	Spring 2
44 210048Carbon	Brush	120V 2
45 210049SST	Self-tapping	Screw	ST2.9×8 4
46 210094Terminal	Block 1
47 210093Speed	Pot	w/Speed	Feed	Back	Sensor	120V 1
48 210053Rear	Cover 1
49 210054Self-tapping	Screw	4.2x14 3
50 210055Cord	Jacket 1
51 210056Twist	Strip 1
52 210057Rubber	Washer 1
53 210058Garden	Hose	Adapter 1
54 210059Spring 1
55 210061Power	Supply	Cord	120V 1
56 133229Water	Hose	8mm	x	10ft	(3m) 1
57 210063Water	Valve	Bracket 1
58 210064Water	Valve	Assembly 1
59 310007Water	Hose		8mm	x	51cm 1
60 210066Cord	Clamp 1
61 210068Switch 1
62 210069Back	Moving	Spring 1
63 210070Switch	Push	Lever 1
64 210071Switch	Push	Button 1
65 210072GFCI	120V 1
66 210078Self-tapping	Screw	4.2x10 2
67 210079Water	Valve	Ta p 1
68 210096Screw	M4x8 1
69 210097Terminal	Connector 1
70 210110Spanner 1