Graco Fuller O'brien Paints Pro 501st Series Operation manual

308–256
Rev. D
Supersedes Rev. B
and PCN C
INSTRUCTIONS-PARTS LIST
INSTRUCTIONS
This manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
ELECTRIC, 120 VAC
Pro 5 01s t A irles s P ain t S prayer
2750 psi (19.0 MPa, 190 bar) Maximum Working Pressure
Model 231–299, Series B
Complete sprayer with hose, gun, Rac IV  DripLess 
T
ip Guard and SwitchT ip.
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
http://www.graco.com
COPYRIGHT
1994, GRACO INC.
Graco Inc. is registered to I.S. EN ISO 9001
02821A


Table of Contents
Warnings 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Startup 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown and Care 11. . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warranty 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Number 36. . . . . . . . . . . . . . . . . . . . . . . .
Symbols
Warning Symbol
WARNING
This symbol alerts you to the possibility of serious
injury or death if you do not follow the instructions.
Caution Symbol
CAUTION
This symbol alerts you to the possibility of damage to
equipment if the you do not follow the instructions.
WARNING
INSTRUCTIONS
EQUIPMENT MISUSE HAZARD
Equipment misuse can cause the equipment to rupture or malfunction and result in serious injury .
 This equipment is for professional use only .

Read all instruction manuals, tags, and labels before operating the equipment.
 Use the equipment only for its intended purpose. If you are not sure, call your Graco distributor .

Do not alter or modify this equipment. Use only genuine Graco parts
 Check equipment daily . Repair or replace worn or damaged parts immediately .

Do not exceed the maximum working pressure of the lowest rated system component. Refer to the
T echnical Data on page 35 for the maximum working pressure of this equipment.
 Use fluids and solvents compatible with the equipment wetted parts. Refer to the T echnical Data
section of all equipment manuals. Read the fluid and solvent manufacturer ’ s warnings.
 Do not use hoses to pull equipment.
 Route hoses away from traffic areas, sharp edges, moving parts, and hot surfaces. Do not expose
Graco hoses to temperatures above 82  C (180  F) or below –40  C (–40 F).

Do not lift pressurized equipment.
 Comply with all applicable local, state, and national fire, electrical, and safety regulations.
W ear hearing protection when operating this equipment.
 Do not use 1,1,1–trichloroethane, methylene chloride, other halogenated hydrocarbon solvents or
fluids containing such solvents in pressurized aluminum equipment. Such use could result in a
chemical reaction, with the possibility of explosion.

 
WARNING
INJECTION HAZARD
Spray from the gun, leaks or ruptured components can inject fluid into your body and cause extremely
serious injury, including the need for amputation. Fluid splashed in the eyes or on the skin can also
cause serious injury .

Fluid injected into the skin may look like just a cut, but it is a serious injury . Get immediate medi -
cal attention.

Do not point the gun at anyone or at any part of the body .

Do not put your hand or fingers over the spray tip.
 Do not stop or deflect leaks with your hand, body , glove or rag.
 Do not “blow back” fluid; this is not an air spray system.
 Always have the tip guard and the trigger guard on the gun when spraying.
 Check the gun dif fuser operation weekly . Refer to the gun manual.
 Be sure the gun trigger safety operates before spraying.
 Lock the gun trigger safety when you stop spraying.
 Follow the Pressure Relief Procedure on page 9 if the spray tip clogs and before cleaning,
checking or servicing the equipment.
T ighten all fluid connections before operating the equipment.
 Check the hoses, tubes, and couplings daily . Replace worn or damaged parts immediately . Do not
repair high pressure couplings; you must replace the entire hose.
 Fluid hoses must have spring guards on both ends, to help protect them from rupture caused by
kinks or bends near the couplings.
TOXIC FLUID HAZARD
Hazardous fluid or toxic fumes can cause serious injury or death if splashed in the eyes or on the skin,
inhaled, or swallowed.
 Know the specific hazards of the fluid you are using.
 Store hazardous fluid in an approved container . Dispose of hazardous fluid according to all local,
state and national guidelines.
 Always wear protective eyewear , gloves, clothing and respirator as recommended by the fluid and
solvent manufacturer .
FUEL HAZARD
The fuel used in this unit is combustible and when spilled on a hot surface can ignite and cause a fire.
 Do not fill the fuel tank while the engine is running or hot.
EXHAUST HAZARD
The exhaust contains poisonous carbon monoxide which is colorless and odorless.
 Do not operate this equipment in a closed building.

308-2564
WARNING
FIRE AND EXPLOSION HAZARD
Improper grounding, poor ventilation, open flames or sparks can cause a hazardous condition and re -
sult in a fire or explosion and serious injury .
 If there is any static sparking or you feel an electric shock while using this equipment, stop spray-
ing immediately . Do not use the equipment until you identify and correct the problem.
 Provide fresh air ventilation to avoid the buildup of flammable fumes from solvents or the fluid
being sprayed.
 Keep the spray area free of debris, including solvent, rags, and gasoline.
 Disconnect all electrical equipment in the spray area.
 Extinguish all open flames or pilot lights in the spray area.
 Do not smoke in the spray area.
 Do not turn on or of f any light switch in the spray area while operating or if fumes are present.
 Do not operate a gasoline engine in the spray area.
 Ground the sprayer to a true earth ground with the ground wire and clamp (supplied).
 Use only electrically conductive hoses.
MOVING P ARTS HAZARD
Moving parts can pinch or amputate your fingers.
 Keep clear of all moving parts when starting or operating the pump.
 Before servicing the equipment, follow the Pressure Relief Procedure on page 9 to prevent the
equipment from starting unexpectedly .
Liquids can be injected into the body by high pressure airless spray
or leaks – especially hose leaks.
Keep body clear of the nozzle. Never stop leaks with any part of the
body. Drain all pressure before removing parts.A void accidental trig -
gering
of gun by always setting safety latch when not spraying.
Never spray without a tip guard.
In case of accidental skin injection, seek immediate
“Surgical
T reatment”.
Failure to follow this warning can result in amputation or serious
injury.
FIRE AND
EXPLOSION HAZARD
SKIN INJECTION
HAZARD
READ AND UNDERSTAND ALL LABELS AND INSTRUCTION MANUALS BEFORE USE
Spray painting, flushing or cleaning equipment with flammable liq -
uids
in confined areas can result in fire or explosion.
Use outdoors or in extremely well ventilated areas. Ground equip -
ment,
hoses, containers and objects being sprayed.
Avoid all ignition sources such as static electricity from plastic drop
cloths, open flames such as pilot lights, hot objects such as ciga -
rettes,
arcs from connecting or disconnecting power cords or turn -
ing
light switches on and off.
Failure to follow this warning can result in death or serious injury .
NOTE: This is an example of the DANGER label on your sprayer . This label is available in other languages, free of
charge.
See page 34 to order .

 
Notes


Setup
Fig. 1




02821A
32
33
64
28
74
102
52
1/4 npsm(m) fluid outlet
Rotate clockwise to increase pressure
Do not install any shutof f device here
Fill 1/3 full with TSL
Shown in closed or spray position





67
WARNING
If you supply your own hoses and spray gun, be
sure the hoses are electrically conductive, that the
gun has a tip guard, and that each part is rated for
at least 2750 psi (19.5 MPa, 195 bar) W orking
Pressure. This is to reduce the risk of serious injury
caused by static sparking, fluid injection or over-
pressurization and rupture the hose or gun.
CAUTION
T o avoid damaging the pressure control, which may
result in poor equipment performance and compo -
nent damage, follow these precautions.
1. Always use a nylon spray hose at least 50 ft (15
m) long.
2. Never use a wire braid hose as it is too rigid to
act as a pulsation dampener .
3.
Never install any shutof f device between the
pump and the hose. See Fig. 1.
1. Connect the hose (74) and gun (67) and screw it
onto the outlet nipple (28). Do not use thread
sealant, and do not install the spray tip yet.
2. Fill the wet-cup (102) . Pry of f the wet-cup seal.
Fill the cup 1/3 full with Graco Throat Seal Liquid
(TSL), supplied. Install the wet-cup seal.
3. Plug in the sprayer . Be sure the ON/OFF switch
(52) is OFF . Plug the cord into a grounded outlet at
least 20 feet away from the spray area.
4. Check the electrical service . Be sure it is 120 V ,
60HzAC, 15 Amp (minimum). Use a properly
grounded outlet. Do not remove the third (ground -
ing) prong of the power supply cord, and do not
use an adapter .
Use a 3-wire, minimum 12 ga (16 AWG), 15 amp
extension cord up to 150 ft. (45 m) long. Longer
lengths af fect sprayer performance.

 
Setup
5. Ground the sprayer and spray system .
WARNING
T o reduce the risk of static sparking, ground the
pump and all other equipment used or located in
the spray area. Check your local electrical code for
detailed grounding instructions for your area and
type of equipment. Ground all of this equipment.
a. Sprayer: plug into a properly grounded outlet.
Do not use an adapter . Extension cords must
have three wires and be rated for at least 15
amps.
b.
Fluid hoses: use only grounded hoses with a
maximum of 500 ft (150 m) combined hose
length to ensure grounding continuity .
c.
Spray gun: obtain grounding through connec -
tion to a properly grounded fluid hose and
sprayer.
d.
Object being sprayed: according to local code.
e. Fluid supply container: according to local code.
f. All solvent pails used when flushing , according
to local code. Use only metal pails, which are
conductive. Do not place the pail on a non-
conductive surface, such as paper or card -
board, which interrupts the grounding continu -
ity.
g.
T o maintain grounding continuity when flushing
or relieving pressure , always hold a metal part
of the gun firmly to the side of a grounded
metal pail, then trigger the gun.
6. Flush the pump to remove the oil which was left
in to protect the pump parts after factory testing.
See page 12.
7. Prepare the paint according to the manufacturer ’s
recommendations. Remove any paint skin. Stir the
paint to mix pigments. Strain the paint through a
fine nylon mesh bag (available at most paint
dealers) to remove particles that could clog the
gun filter or spray tip. This is an important step
toward trouble-free spraying.
Operation
How to Use the Gun Trigger Safety
When locked, the gun trigger safety prevents the gun
from accidental triggering. See Fig. 2.
WARNING
If the gun sprays when the gun trigger safety is
locked, adjust the gun. See manual 307–614,
supplied.
Locked
Unlocked
Fig. 2




How to Use the Pressure Drain Valve
Use the pressure drain valve to relieve fluid pressure
from the pump and to help prime the pump. If the valve
senses an over pressure condition, it opens automati -
cally to relieve fluid pressure. If this happens, stop
spraying immediately, shut of f and unplug the sprayer .
Determine the cause of the problem and correct it
before operating the sprayer again. Refer also to
Troubleshooting , page 13. See Fig. 3.
Closed, or spray position
Open or drain, position
Fig. 3




02825A


Operation
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
How to Use the Pressure Control
The pressure control controls the motor operation so
the sprayer maintains constant fluid pressure at the
pump outlet. T urn the pressure control knob fully
counterclockwise to obtain the minimum setting. T urn
the knob clockwise to increase pressure. See Fig. 4.
Fig. 4
+
–
02824A
How to Use the RAC IV Tip Guard
WARNING
To reduce the risk of serious injury from fluid injec -
tion:
Never operate the spray gun with the tip guard
removed.
Do not hold your hand, body , or a rag in front of the
spray tip when cleaning or checking a clogged tip.
Always point the gun toward the ground or into a
pail when checking to see if the tip is clear .
Do not try to “blow back” paint; this is not and air
spray sprayer .
The tip guard alerts you to the risk and helps prevent
placing any part of the body close to the spray tip. The
tip guard also adjusts the vertical or horizontal spray
pattern. See page 10. The tip guard holds a reversing
spray tip. The tip is in the spraying position when the
tip handle points forward. See Fig. 5.
Clean the front of the tip frequently during the day’ s
operation. First, relieve the pressure .
0484
Fig. 5
Tip handle shown in
spraying position.
T urn handle 180 ,
trigger gun to clear clog
1
2
1 2
How to Remove a Tip Clog
1. Release the gun trigger . Lock the safety latch.
Rotate the RAC IV tip handle 180  . See Fig. 5.
2. Unlock the safety latch. T rigger the gun into a pail
or onto the ground to remove the clog.
3. Lock the safety latch. Rotate the tip handle to the
spraying position.
4. If the tip is still clogged, lock the safety latch, shut
of f and unplug the sprayer , and open the pressure
drain valve to relieve pressure. Clean the spray tip
as shown in manual 307–848, supplied.

 
Startup
Pressure Relief Procedure
WARNING
INJECTION HAZARD
The system pressure must be manually
relieved to prevent the system from
starting or spraying accidentally . Fluid
under high pressure can be injected through the
skin and cause serious injury . T o reduce the risk of
an injury from injection, splashing fluid, or moving
parts, follow the Pressure Relief Procedure
whenever you:
 are instructed to relieve the pressure,
 stop spraying,
 check or service any of the system equipment,
 or install or clean the spray tip.
1. Lock the gun trigger safety .
2. T
urn the ON/OFF switch to OFF .
3. Unplug the power supply cord.
4. Unlock the trigger safety . Hold a metal part of the
gun firmly to the side of a grounded metal pail, and
trigger the gun to relieve the pressure.
5. Lock the gun trigger safety .
6. Open the pressure drain valve, having a container
ready to catch the drainage. Leave the valve open
until you are ready to spray again.
If you suspect that the spray tip or hose is completely
clogged, or that pressure has not been fully relieved
after following the steps above, VER Y SLOWL Y
loosen the tip guard retaining nut or hose end coupling
to relieve the pressure gradually , then loosen com -
pletely
. Now clear the tip or hose.
Startup Procedure
Use this procedure each time you start the sprayer to
help ensure the sprayer is ready to operate and that
you start it safely .
NOTE: If this is a first-time startup, flush the sprayer .
See page 12.
NOTE: Refer to Fig. 1 and other figures referenced in
the text as you start the sprayer .
1.
Open the pressure drain valve (42) .
2. Do not install the spray tip until the pump is
primed.
3. Put the suction hose (32) into the paint
. If you
are pumping from a pail, push the drain hose (33)
down below the top of the pail to avoid splashing
paint wen the drain valve is opened.
4. T urn the pressure knob (64) to the minimum
setting.
5. Unlock the gun trigger safety
. See Fig. 2, page
7.
CAUTION
T o reduce the risk of damage to the displacement
pump packings, never run the pump without fluid in
it for more than 30 seconds.
6. T o prime the pump , turn the sprayer switch (52)
on. Slowly increase the pressure until the sprayer
starts. When fluid comes from the pressure drain
valve, close the valve.
WARNING
T o reduce the risk of static sparking and splashing
when flushing, always remove the spray tip from
the gun, and hold a metal part of the gun firmly to
the side of, and aimed into, a grounded metal pail.
See Ref. A in Fig. 6.
Fig. 6 01024
A
7. T o prime the hose , lower the pressure to reduce
splashing. Hold a metal part of the gun firmly
against and aimed into a grounded metal pail. See
the WARNING above. Hold the trigger open and
slowly increase the pressure until the pump starts.
Keep the gun triggered until all air is forced out of
the system and the fluid flows freely from the gun.
Release the trigger and lock the gun trigger safety .

308-25610
Setup
8. Check all fluid connections for leaks. Relieve the
pressure before tightening any connections.
9. Install the spray tip. Lock the gun trigger safety
first. See manual 307–848 for how to install the tip.
10. Adjust the spray pattern.
a. Increase the pressure just until spray from the
gun is completely atomized. T o avoid exces -
sive overspray and fogging, and to extent tip
and sprayer life, always use the lowest pres -
sure required to get the desired results.
b. If more coverage is needed, use a larger tip
rather than increasing the pressure.
c. T est the spray pattern. T o adjust the direction
of the spray pattern, lock the gun trigger safety
and loosen the retaining nut (A). Position the
tip guard horizontally for a horizontal pattern or
vertically for a vertical pattern. Hold the tip
guard in place while tightening the retaining
nut. See Fig. 7.
NOTE: Spray patterns will change as tips wear .
Change the spray tip if adjusting the pressure will not
improve the spray pattern.
For a horizontal
spray pattern
For a vertical
spray pattern
Fig. 7




A

308-256 11
Shutdown and Care
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
1. Check the packing nut/wet-cup daily (102).
Relieve the pressure and unplug the sprayer .
Keep the wet-cup 1/3 full of TSL at all times to
help prevent fluid buildup on the piston rod and
premature wear of packings.
2. Tighten the packing nut/wet-cup (102) just
enough to stop leakage
. Over-tightening causes
binding and excessive packing wear . Use a round
punch or brass rod and a light hammer to adjust
the nut. See Fig. 8.
3. Clean the gun’s fluid filter often and whenever
the gun is stored. Relieve the pressure
first.
Refer to manual 307–614.
4. Periodically clean paint residue from the pres -
sure transducer (29) vent hole area. See Fig. 8.
Replace the transducer when leakage is exces -
sive. See page 29.
5. Lubricate the bearing housing after every 100
hours of operation. Remove the front cover . Fill the
bearing housing cavity (A) with SAE 10 non-deter -
gent oil. See Fig. 9.
6. Flush the sprayer at the end of each work day
and fill it with mineral spirits to help prevent pump
corrosion and freezing. See page 12.
CAUTION
T o prevent pump corrosion, and to reduce the
chance of fluid freezing in the pump in cold weather ,
never leave water or any type of paint in the sprayer
when it is not in use. Freezing can seriously dam -
age the spray or result in a loss of pressure or
stalling.
7. For very short shutoff periods, leave the suction
hose in the paint, relieve the pressure, and clean
the spray tip.
8. Coil the hose when storing it, even for overnight,
to help protect the hose from kinking, abrasion,
coupling damage, etc.
Turn packing
nut clockwise to
tighten
Fig. 8

+
–
102
02829A
Fig. 9

Vent
hole
29
A

02827A

308-25612
Flushing
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
When to Flush
1. Before using a new sprayer: flush out the oil
which was left in to protect pump parts.
Before using water-base paint: flush with miner -
al spirits followed by soapy water , and then a clean
water flush.
Before using oil-base paint: flush with mineral
spirits only .
2. Changing colors:
flush with compatible solvent
such as mineral spirits or water .
3. Changing from water-base to oil-base paint:
flush with warm, soapy water , and then mineral
spirits.
4. Changing from oil-base to water-base paint:
flush with warm, soapy water , and then a clean
water flush.
5. Storage after using water-base paint: flush with
water and then mineral spirits. Leave the system
filled with mineral spirits. Relieve the pressure .
Leave the drain valve open.
CAUTION
Never leave water or water-based fluids in the
sprayer if there is a chance is could freeze. Push
the water out with mineral spirits. Frozen fluids in
the sprayer prevents it from being started and may
cause serious damage.
6. Startup after storage . Before using water-base
paint, flush out the mineral spirits with soapy water
and then clean water . When using oil-base paint,
flush out the mineral spirits with the paint.
How to Flush
1. Relieve the pressure.
2. Remove the spray tip and clean it separately .
Remove the filter screen and reinstall the bowl,
hand tight, without the screen. Clean the screen
separately . See Fig. 10.
Fig. 10
SCREEN
BOWL
3. Pour one-half gallon (2 liters) of compatible solvent
into a grounded metal flushing pail. Put the suction
hose in the pail.
4. Ope n t h e p ressur e d rai n v alve . S ee Fig . 3, p ag e 7.
5. T o save the paint still in the pump and hose, follow
Step 6, except put the drain hose in the paint pail.
When solvent appears, close the drain valve. Put
the drain hose in the flushing pail. T rigger the gun
into the paint pail. When solvent appears, release
the trigger . Continue with step 6.
WARNING
T o reduce the risk of static sparking and splashing
when flushing, always remove the spray tip from
the gun, and hold a metal part of the gun firmly to
the side of, and aimed into, a grounded metal pail.
See Ref. A in Fig. 1 1.
Fig. 11 01024
A
6. Lower the pressure setting. T urn on the sprayer .
Maintaining metal-to-metal contact, trigger the gun
into the flushing pail. Slowly increase the sprayer
pressure until the pump starts. Keep the gun
triggered until the solvent flows freely from the
gun. Circulate the solvent to thoroughly clean the
sprayer . Release the gun trigger . Lock the gun
trigger safety .
7.
Open the drain valve and circulate the solvent
through the drain hose to thoroughly clean it.
Close the drain valve.
8. Remove the suction hose from the pail. Unlock the
gun trigger safety . T rigger the gun and run the
pump a few seconds to push air into the hose. Do
not run the pump dry for more than 30 seconds to
avoid damaging the pump packings. Relieve the
pressure.
9.
Remove and clean the inlet strainer . Wipe paint of f
the suction hose and drain hose.
10. Refer to When to Flush , Step 1 again. Relieve
the pressure.
11. Leave the drain valve open until you use the
sprayer again.

308-256 13
Troubleshooting
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
Check everything in the chart before disassembling the sprayer .
Basic Problem Solving
Check everything in the guide before disassembling the sprayer .
TYPE OF PROBLEM WHA T T O CHECK
If check is OK, go to next check
WHA T T O DO
When check is not OK, refer to this column
Fluid pressure 1. Check pressure control knob setting. The pump
won’t develop much pressure if it is at minimum
setting (fully counterclockwise).
1. Slowly increase pressure setting to see if
motor starts.
2. Check for a clogged spray tip or fluid filter , if
used. See page 8.
2. If tip is still clogged, relieve pressure; re -
fer to separate gun or tip instruction man -
ual for tip cleaning. Clean or replace filter
element. See manual 308–249.
Mechanical 1. Check for frozen or hardened paint in pump
(20). Using a screwdriver , carefully try to rotate
fan at back of motor by hand. See page 17.
1. Thaw . Plug in sprayer and turn on.
Slowly increase pressure setting to see if
motor starts. If it doesn’t, see NOTE, be -
low.
2. Check pump connecting rod pin (17). It must be
completely pushed into connecting rod (15),
and retaining spring (18) must be firmly in con -
necting rod groove. See Fig. 18, page 20
2. Push pin into place and secure with
spring retainer .
3. Check for motor damage. Remove drive hous -
ing assembly (1 1). See page 26. T ry to rotate
motor fan by hand.
3. Replace motor (4) if fan won’t turn. See
page 24.
Electrical 1. Check electrical supply with volt meter . Meter
should read 105–125 V AC.
1. Reset building circuit breaker; replace
building fuse. T ry another outlet.
2. Check extension cord for visible damage. Use
a volt meter or test lamp at extension cord out -
let to check.
2. Replace extension cord.
3. Check sprayer power supply cord (50) for vis-
ible damage such as broken insulation or wires.
3. Replace power supply cord.
See page 25.
4. Check motor brushes for the following:
a. Loose terminal screws.
b. Broken or misaligned brush springs.
c. Brushes binding in holders.
d. Broken leads.
e. W orn brushes.
NOTE: The brushes do not wear at same rate
on both sides of motor . Check both brushes.
4. Refer to page 19.
a. Tighten.
b.
Replace broken spring and/or align
spring with brush
c. Clean brush holders. Remove carbon
with small cleaning brush. Align brush
leads with slot in brush holder to as -
sure free vertical brush movement.
d. Replace brushes
e. Replace brushes if less than long.
NOTE: Thaw sprayer if water or water–based paint has frozen in it, due to exposure to low temperatures, by placing in a warm
area. Do not try to start sprayer until completely thawed or damage to motor and/or start board may occur
. If paint hardened
(dried) in sprayer , the pump packings (page 20) and/or pressure transducer (page 29) must be replaced.

308-25614
Basic Problem Solving
TYPE OF PROBLEM WHA T T O CHECK
If check is OK, go to next check
WHA T T O DO
When check is not OK, refer to this column
Electrical (continued) 5. Check motor armature commutator for burn
spots, gouges and extreme roughness. Re -
move motor cover and brush inspection plates
to check. See page 19.
5. Remove motor and have motor shop
resurface commutator if possible. See
page 24.
6. Check motor armature for shorts using arma -
ture tester (growler) or perform motor test.
See page 17.
6. Replace motor . See page 24.
7. Check leads from pressure control and motor to
motor start board (47) to be sure they are se -
curely fastened and properly mated.
7. Replace loose terminals; crimp to leads.
Be sure male terminal blades are straight
and firmly connected to mating part.
8. Check motor start board (47) by substituting
with a good board. See page 25.
CAUTION: Do not perform this check until mo -
tor armature is determined to be good. A bad
motor armature can burn out a good board.
8. Replace board. See page 25.
9. Check power supply cord (50). Disconnect
black and white power cord terminals; connect
volt meter to these leads. Plug in sprayer . Meter
should read V AC. Unplug sprayer .
9. Replace power supply cord. See page
25.
10. Check ON/OFF switch (52). Disconnect the “L”
wire between the motor start board (47) and
switch and connect volt meter between ex -
posed terminal on switch and power cord’ s
white wire . Plug in sprayer and turn ON . Meter
should read V AC. T urn of f and unplug sprayer .
10. Replace ON/OFF switch. See page 25.
11. Check motor thermal cutout switch. Connect
ohmmeter between motor ’ s red leads. Meter
should read 1 ohm maximum.
11. Allow motor to cool. Correct cause of
overheating. If switch remains open after
motor cools, replace motor .
12. Remove pressure control (64) and check mi -
croswitch operation with ohmmeter:
(1) With pressure knob at lowest setting and
stem pushed into control, readings should
be: white & black = 1 ohm max.
white & red = open.
(2) With pressure knob at highest setting,read -
ings should be: white & black = open;
white & red = 1 ohm max.
12. Replace pressure control. See page 28.
13. Check pressure transducer (29) for hardened
paint or damaged or worn components. See
page 29.
13. Replace transducer . See page 29. Thor -
ough system flushing will help extend life
of transducer .
Intermediate Problem Solving
TYPE OF PROBLEM WHA T T O CHECK
If check is OK, go to next check
WHA T T O DO
When check is not OK refer to this column
Low output 1. Check for worn spray tip. 1. Follow Pressure Relief Procedure then
replace tip. See your separate gun or tip
manual.
2. Be sure pump does not continue to stroke
when gun trigger is released. Plug in and turn
on sprayer . Prime with paint. T rigger gun mo -
mentarily
, then release and lock safety latch.
Relieve pressure, turn of f and unplug sprayer .
2. Service pump. See page 20.

308-256 15
Intermediate Problem Solving
TYPE OF PROBLEM WHA T T O CHECK
If check is OK, go to next check
WHA T T O DO
When check is not OK, refer to this column
Low output (continued) 3. Release gun trigger . Observe resting position of
pump rod (107).
3. If pump consistently comes to rest with
rod (107) fully extended, the piston pack -
ings and/or piston valve may be worn.
Service the pump. See page 20.
4. Check electrical supply with volt meter . Meter
should read V AC.
4. Reset building circuit breaker; replace
building fuse. Repair electrical outlet or
try another outlet.
5. Check extension cord size and length; must be
at least 3 wire and less than 150 ft (45 m) .
5. Replace with a correct, grounded exten -
sion cord.
6. Check motor brushes. See Electrical – What T o
Check, item 4, on page 13
6. See page 19.
7. Check motor start board (47) by substituting
with a good board.
CAUTION: Do not perform this check until mo -
tor armature is determined to be good. A bad
motor armature can burn out a good board.
7. Replace board. See page 25.
8. Check motor armature for shorts by using an
armature tester (growler) or perform motor test.
See page 17.
8. Replace motor . See page 24.
Drain valve leaks 1. Check drain valve for correct torque and/or
worn parts. Check for debris trapped on seat.
9. T ighten to 185 in–lb (21 N.m) . Clean
valve and replace with new gasket (42a)
and sealant (42d). See page 31.
Transducer leaks 1. Slight leakage from transducer is normal. 1. Periodically remove residue from its cyl -
inder port. See page 29.
No output: motor runs and
pump strokes
1. Check paint supply . 1. Refill and reprime pump.
2. Check for clogged intake strainer . 2. Remove and clean, then reinstall.
3. Check for loose suction tube or fittings. See
page 30.
3. T ighten; use thread sealant on npt
threads of inlet tube (38). Check for dam -
aged o–ring (27).
4. Check to see if intake valve ball and piston ball
are seating properly . See page 20.
4. Remove intake valve and clean. Check
ball and seat for nicks; replace as need -
ed. See page 20. Strain paint before us -
ing to remove particles that could clog
pump.
5. Check for leaking around throat packing nut
which may indicate worn or damaged packings.
See page 20.
5. Replace packings. See page 20. Also
check piston valve seat for hardened
paint or nicks and replace if necessary .
T ighten packing nut/wet-cup.
6. Release gun trigger . Observe resting position of
pump rod (107).
6. If pump consistently comes to rest with
rod (107) fully extended, the piston pack -
ings and/or piston valve may be worn.
Service the pump. See page 20.
No output: motor runs but
pump does not stroke
1. Check displacement pump connecting rod pin
(17). See Fig. 18, page 20.
1. Replace pin if missing. Be sure retainer
spring (18) is fully in groove all around
connecting rod.
7. Check connecting rod assembly (15) for dam -
age. See page 26.
7. Replace connecting rod assembly . See
page 26.
8. Be sure crank in drive housing rotates; plug in
sprayer and turn on briefly to check. T urn of f
and unplug sprayer . See page 26.
8. Check drive housing assembly for
damage and replace if necessary . See
page 26.

308-25616
Intermediate Problem Solving
TYPE OF PROBLEM WHA T T O CHECK
If check is OK, go to next check
WHA T T O DO
When check is not OK, refer to this column
Spray pattern variations
1. Spray tip worn beyond sprayer pressure
capability.
1. Replace spray tip.
NOTE: A smaller size tip will provide
longer life.
2. Check transducer (29) for wear or damage. 2. Replace transducer . See page 29.
3. Check pressure control (64) for smooth
operation.
3. Replace pressure control. See page 28.
4. Check Low output section, page 15.
Motor is hot and runs
intermittently
1. Determine if sprayer was operated at high pres -
sure with small tips, which causes excessive
heat build up.
1. Decrease pressure setting or increase tip
size.
2. Be sure ambient temperature where sprayer is
located is no more than and sprayer is not lo -
cated in direct sun.
2. Move sprayer to shaded, cooler area if
possible.
3. Check motor. 3. Replace motor . See page 24.
Building circuit breaker opens
as soon as sprayer switch is
turned
on.
1. Check all electrical wiring for damaged insula -
tion, and all terminals for loose fit or damage.
Also check wires between pressure control and
motor . See page 28.
1. Repair or replace any damaged wiring or
terminals. Securely reconnect all wires.
2. Check for missing motor brush inspection plate
gasket (see page 17), bent terminal forks or
other metal to metal contact points which could
cause a short.
2. Correct faulty conditions.
3. Check motor armature for shorts. Use an arma -
ture tester (growler) or perform motor test. See
page 17. Inspect windings for burns.
3. Replace motor . See page 24.
4. Check motor start board (47) by substituting
with a good board.
CAUTION: Do not perform this check until
motor armature is determined to be good. A
bad motor armature can burn out a good board.
4. Replace board. See page 25.
Circuit breaker opens after
sprayer operates for 5 to 10
minutes.
1. Check ‘Basic Problems – Electrical’ on
page 13.
Building circuit breaker
opens as soon as sprayer
is plugged into outlet and
1. Check electrical supply with volt meter . Meter
should read V AC.
1. If voltage is too high, do not operate
sprayer until corrected.
ppy
is plugged into outlet and
sprayer is NOT turned on.
2. Check tightness of pump packing nut. Over -
tightening tightens packings on rod, restricts
pump action, damages packings.
2. Loosen packing nut. Check for leaking
around throat. Replace pump packings, if
necessary . See page 20.
3. Check for damaged motor . 3. Replace motor . See page 24.
4. Check ON/OFF switch (52). Be sure sprayer is
unplugged!
Disconnect wires from switch.
Check switch with ohmmeter . The reading
should be infinity with ON/OFF switch OFF , and
zero with switch ON.
CAUTION:
A short in motor circuit can damage
switch and or motor start board (47).
4. Replace ON/OFF switch. See page 25.
Unit will not run on gener -
ator but does run on AC
power
1. Check the generator ’ s “peak” voltage. This
sprayer will not run if the peak voltage is above
190V.
1. Use AC power or a dif ferent generator

308-256 17
Motor T est
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
For checking armature, motor winding, and brush
electrical continuity .
Setup
Remove the drive housing. See page 26. This is to
ensure that any resistance you notice in the armature
test is due to the motor and not to worn gears in the
drive housing.
Remove the motor brush inspection covers (A). See
Fig. 12.
Remove the junction box screws (56). Lower the
junction box. Disconnect the two leads (C) from the
motor to the board (47). See Fig. 13.
Armature Short Circuit
Remove the handle (24) and the fan cover (B). See
Fig. 12.
Spin the motor fan by hand. If there are no shorts, the
motor will coast two or three revolutions before coming
to a complete stop. If the motor does not spin freely
,
the armature is shortened and the motor must be
replaced. See page 24.
Armature, Brushes, and Motor Wiring
Open Circuit Test (Continuity)
Connect the two black motor leads together with a test
lead. T urn the motor fan by hand at about two revolu -
tions per second.
When turning the fan on a DC motor, normally you
sense an even, pulsing resistance. If there is irregular
turning resistance, check and repair the following as
needed: broken brush springs, brush leads, motor
leads; loose brush terminal screws or motor lead
terminals; worn brushes. See page 19.
If there is still uneven or no turning resistance, replace
the motor . See page 24.
A
B
Fig. 12 02829A
MOTOR
BLACK/
WHITE
BLACK
C
59
RED
Fig. 13
47

308-25618
General Repair Information
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
Tool List
These are tools required to service all parts of the
sprayer.
3/16” Allen  wrench: gear housing, legs, handle
3/8” Allen  wrench: pump manifold
#1 Phillips  screwdriver junction box, pressure control,
front cover
3/8” socket wrench:
motor mount
5/8” socket wrench: drain valve, outlet fittings,
on/of f switch boot, piston
13/16” socket wrench: drain valve
1–1/4” socket wrench: pump inlet valve
1/2” open end wrench:
pump rod
1 1/16” open end wrench: piston jam nut
15/16” open end wrench: flats of inlet tube
1–3/4” open end wrench: pump ham nut
5/64” drive pin: drain valve pin
3” needle nose pliers: wiring, on/of f switch
Hammer & punch: packing nut
T orque wrenches: various fasteners
1. When disconnecting wires in the junction box
assembly , use needle nose pliers to separate
mating connectors.
2. When reconnecting the wires , be sure the flat
blade of the insulated male connector is centered
in the wrap-around blade of the female connector .
CAUTION
T o reduce the risk of pressure control malfunction,
be sure to properly mate connectors, and never pull
on a wire to disconnect it. Pulling on a wire could
loosen the connector from the wire.
3. Route wire carefully through the drive housing
and motor . A void pinching the wires between the
junction box and the motor or pressure control.
CAUTION
Improper wire routing can result in poor sprayer
performance or damage to the pressure control.
4. Keep all screws, nuts, washers, gaskets, and
electrical fittings removed during repair proce -
dures. These parts are not normally provided with
replacement assemblies.
5. T est your repair before regular operation to be
sure the problem is corrected.
6. If the sprayer does not operate properly , verify
that everything was done correctly. Also refer to
Troubleshooting , pages 13–16, to help identify
other possible problems and solutions.
WARNING
T o reduce the risk of serious injury , including elec -
tric shock. Do not touch any moving parts or elec -
trical parts with your fingers or a tool while inspect -
ing the repair .
Shut of f the sprayer and unplug it as soon as you
complete the inspection.
Reinstall all covers, gaskets, screws, and washers
before operating the sprayer .
WARNING
During operation, the motor and drive housing
become very hot and could burn your skin if
touched. Flammable materials spilled on the hot,
bare motor could cause a fire or explosion.

308-256 19
Motor Brushes
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
NOTE: Replace brushes when worn to about 0.5 in
(12.5 mm). Always check both brushes. Brush Repair
Kit 236–967 is available for motors manufactured by
Pacific Scientific. Consult Rev . A of this manual for
repair kit and instructions if your motor has a Leeson
motor.
NOTE: Replacement brushes may last only half as
long as the original ones. To maximize brush life, break
in new brushes by operating the sprayer with no load
as instructed in this procedure.
1. Relieve the pressure Unplug the sprayer .
2.
Remove both inspection covers (A) and their
gaskets. See Fig. 14.
A
Fig. 14 02831A
3. Push in the spring clip (F) and release its hook (G)
from the brush holder (B). Pull out the spring clip.
See Fig. 15.
4. Slide of f the brush lead terminal (E) of f the blade
connector . Remove the old brush (C). See Fig. 15.
5. Inspect the commutator for excessive pitting,
burning, or gouging. A black color on the commu -
tator is normal. Have the commutator resurfaced
by a qualified motor repair shop if the brushes
seem to wear too fast or arc excessively . See Step
10.d, also.
6. Repeat for the other side.
NOTE: The motor brushes on the other side are
upside down.
7. Place a new brush (C) in the holder (B) so the
ramp (H) faces the spring. See Fig. 15.
8. Holding the spring clip (F) at a slight angle, slide
the spring clip into the brush holder and hook it
over the end of the holder . See Fig. 16. Pull on the
spring clip to be sure it stays in place.
9. Repeat for the other side.
10. Test the brushes.
a.
Remove the pump connecting rod pin (17).
See Fig. 18, page 20.
b. With the sprayer OFF , turn the pressure con -
trol knob fully counterclockwise to minimum
pressure. Plug in the sprayer .
c. T
urn the sprayer ON. Slowly increase the
pressure until the motor is at full speed.
d. Inspect the brush and commutator contact
area for excessive arcing. Arcs should not
circle around the commutator surface.
WARNING
Do not touch the brushes, leads, springs, or brush
holders while the sprayer is plugged in to reduce
the risk of electric shock and serious injury .
11. Install the brush inspection covers and gaskets.
12. Break in the brushes . Operate the sprayer for at
least one hour with no load. Install the pump
connecting rod pin.
Fig. 15
F
G
E
D
C
B
H
1
1
Motor
lead; do not disconnect
2
Minimum 0.5” (12.5 mm)
2
03881
Fig. 16
1
G
C
E
F


Displacement Pump Repair
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 9.
Removing the Pump (See Fig. 17)
1. Flush the pump, if possible. Relieve the pressure .
Stop the pump with the piston rod (107) in its
lowest position, if possible. T o lower the piston rod
manually , rotate the motor fan blades.
2. While pulling upward on the suction hose (32),
unscrew the hose from the inlet tube (38). Un -
screw the drain hose (33) from the displacement
pump nipple (36).
NOTE: If repairing only the intake valve assembly , go
to Intake V
alve Repair , page 21.
3. Use a screwdriver to push the retaining spring (18)
up and push out the pin (17).
4. Loosen the screws (21). Remove the pump (20).
Installing the Pump (See Fig. 17 and 18)
1. Mount the pump on the drive housing. T ap it into
the alignment pins with a soft hammer . T ighten the
screws (21) to 50 ft-lb (68 M m).
2.
Align the hole in the rod (107) with the connecting
rod assembly (15). Use a screwdriver to push the
retaining spring (18) up and push in the pin (17).
Push the retaining spring (18) into place around
the connecting rod.
WARNING
Be sure the retaining spring (18) is firmly in the
groove al the way around, to prevent the pin (17)
from working loose due to vibration. See Fig. 18.
If the pin works loose, it or other parts could break
of f due to the force of the pump action. These parts
could be projected into the air and result in serious
injury or property damage, including the pump
connecting rod or bearing housing.
3. Replace the o-ring (27) if it is worn or damaged.
Reconnect the suction and drain hoses (32, 33).
Install the front cover (13).
4. T ighten the packing nut (102) just enough to stop
leakage, but no tighter
. Fill the packing nut/wet-cup
1/4 full with Graco TSL. Push the plug (123) into
the wet-cup.
Fig. 17 01067A


Torque
to
50 ft–lb (68 N.m)
Apply sealant (42d)
118
*119
*121
*122
120
17
18
20

33
32
27
38
21

13
107
17
18
123
15
Fig. 18
21 102
Torque
to
50 ft–lb (68 N.m

01068