Graco 231-547 Operation manual

308–634
Rev. A
02821A
INSTRUCTIONS-PARTS LIST
INSTRUCTIONS
This manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
ELECTRIC, 120 VAC
450 st Airless Paint Sprayer
2750 psi (195 bar) Maximum Working Pressure
Model 231–547, Series A
Complete sprayer with hose, gun, RAC IV  DripLess 
T
ip Guard and SwitchT ip
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
COPYRIGHT 1995, GRACO INC.
Graco Inc. is registered to I.S. EN ISO 9001

 
Table of Contents
Warnings 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Identification and Function 5. . . . . . . . . . . .
Setup 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Startup 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown and Care 11. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor Test 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Repair Information 18. . . . . . . . . . . . . . . . . . . . .
Motor Brush 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump Repair 21. . . . . . . . . . . . . . . . . . . . .
Motor 25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Motor Start Board 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Cord 26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
ON/OFF Switch 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive Housing, Connecting Rod, Crankshaft 27. . . . . .
Pressure Control 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Transducer 30. . . . . . . . . . . . . . . . . . . . . . . . . .
Suction Hose 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drain V alve 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump Parts Drawing and List 33. . . . . .
Sprayer Parts Drawing 34. . . . . . . . . . . . . . . . . . . . . . . . .
Sprayer Parts List 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco W arranty and Disclaimers 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
or destruction of equipment if you do not follow the
instructions.
FIRE AND EXPLOSION HAZARD
Improper grounding, poor ventilation, open flames or sparks can cause a hazardous condition and
result 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
spraying 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.
 Electrically disconnect all 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.
WARNINGWARNING

 
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 .
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 .
INJECTION HAZARD
Spray from the gun, leaks or ruptured components can inject fluid into your body and cause ex -
tremely 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 is a serious injury . The injury may look like just a cut, but it is a serious
injury . Get immediate medical 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.
WARNINGWARNING

 
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 Graco T echnical Assis -
tance at 1–800–543–0339.
 Do not alter or modify this equipment.
 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 36 for the maximum working pressure of this equipment.
 Use fluids and solvents which are 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 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.
 Do not use hoses to pull equipment.
 Route hoses away from traffic areas, sharp edges, moving parts, and hot surfaces. Do not ex -
pose 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.
WARNINGWARNING
INSTRUCTIONS
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 36 to order .

308-634 5
02823A
Component Identification and Function
C
Fig. 1
G
E
F
D
A
K
M
B
H
N
J
L
AMotor DC motor , 120 V ac, 15A, 1 phase
B Drive Assembly T ransfers power from DC motor to the displacement pump
C Pressure Adjusting Knob Controls fluid outlet pressure
D ON/OFF Switch Power switch that controls 120 V ac power to sprayer
E Fluid Outlet Hose and spray gun is connected here
F Displacement Pump Pressurizes fluid to be sprayed through spray gun
G 50 ft (15 m) Main Hose 1/4 in. ID, grounded, nylon hose with spring guards on both ends
H RAC IV T ip Guard Reverse-A-Clean (RAC) tip guard reduces the risk of fluid injection
injury
J Contractor Gun High pressure spray gun with gun safety latch
K RAC IV Switch T ip RAC switch tip atomizes fluid and removes clogs from spray tip without
removing tip from spray gun
L Pressure Drain V alve Relieves fluid pressure when open
M Pressure Control Controls motor to maintain fluid pressure. W orks with pressure
adjusting knob.
N Spray Gun Safety Latch Inhibits accidental triggering of spray gun

 
Setup
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 (195 bar) Working Pressure . This
is to reduce the risk of serious injury caused by
static sparking, fluid injection or over-pressurization
and rupture of the hose or gun.
CAUTION
T o avoid damaging the pressure control, which
may result in poor equipment performance and
component 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
filter and the hose. See Fig. 2.
1. Connect the hose (74) and gun (67) and screw it
onto the outlet nipple (28). Don’t use thread
sealant, and don’t 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 15A grounded
outlet at least 20 feet away from the spray area. A
12 A WG 150 ft (45 m) grounded extension cord
may be used.
FIRE AND EXPLOSION HAZARD
Proper electrical grounding is essential
to reduce the risk of fire or explosion
which can result in serious injury and
property damage. Also read FIRE OR
EXPLOSION HAZARD on page 2.
WARNING
4. Flush the pump to remove the lightweight oil
which was left in to protect pump parts after fac -
tory testing. See page 12.
5. Prepare the paint according to the manufactu -
ers’
s recommendations. Remove any paint skin.
Strain the paint through a fine nylon mesh bag
(available at most paint dealers) to remove par -
ticles that could clog the spray tip. This is an
important step toward trouble-free paint spraying.
Fig. 2




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

32
33
64
28
74
102
52




67
02823A

308-634 7
Operation
How to use the gun trigger safety
When engaged, the gun safety latch prevents the gun
from accidental triggering. See Fig. 3.
WARNING
INJECTION HAZARD
If the gun still sprays when the gun trig -
ger safety is locked, repair the gun. See
manual 307–614, supplied.
Fig. 3

Gun
safety latch
shown disengaged


Gun safety latch
shown engaged
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 the
Troubleshooting , page 13. See Fig. 4.
Fig. 4
Closed, or spray position
Open or drain, position


1
2
02825
A
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. 5.
Fig. 5
+
–
02824A

 
Operation
How to use the RAC IV tip guard.
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.
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 Fig. 8. The tip guard holds a reversing
spray tip. The tip is in the spraying position when the
tip handle points forward. See Fig. 6.
Clean the front of the tip frequently during the day’ s
operation. First, follow the Pressure Relief Procedure
on page 9.
Fig. 6
Tip handle shown in
spraying position.
T urn handle 180 ,
trigger gun to clear clog
1
2
2
1
04647
How to remove a tip clog.
1. Release the gun trigger . Lock the safety latch.
Rotate the RAC IV tip handle 180  . See Fig. 6.
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.

308-634 9
Startup
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.
WARNING
Pressure Relief Procedure
1. Engage the gun safety latch.
2. T urn the ON/OFF switch to OFF .
3. Unplug the power supply cord.
4. Disengage the gun safety latch. Hold a metal part
of the gun firmly to a grounded metal pail. T rigger
the gun to relieve pressure.
5. Engage the gun safety latch.
6. Open the pressure drain valve. Leave the pressure
drain 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 loos -
en the tip guard retaining nut or hose end coupling to
relieve pressure gradually , then loosen completely .
Now clear the tip or hose obstruction.
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. 2 and the other figures referenced
in the text as you start the sprayer .
1.
Open the pressure drain valve (42). See Fig. 7.
2. Don’t 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 when the drain valve is opened.
01021A
Open or drain, position
Fig. 7



4. T urn the pressure knob (64) to the minimum
setting.
5. Disengage the gun trigger safety
. See Fig. 3,
page 7.
CAUTION
Do not run the sprayer dry for more than 30 sec -
onds to avoid damaging the pump packings.
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.

10 308-634
Startup
WARNING
FIRE AND EXPLOSION HAZARD
T o reduce the risk of static sparking and
splashing when priming or flushing the
system, hold a metal part of the gun
firmly to the side of a grounded metal pail before
triggering the gun.
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 preceding W ARNING. Hold the gun 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 engage the
gun safety latch.
8. Check all fluid connections for leaks . Relieve
pressure before tightening the connections.
9. Engage the gun safety latch.
10. Install the spray tip and tip guard. Install the
spray tip. If you are using the RAC IV tip guard,
refer to manual 307–848 for installation instruc -
tions.
11. Adjust the spray pattern
a.
Increase the pressure until spray from the gun
is completely atomized. T o avoid excessive
overspray and fogging, and to extend tip and
sprayer life, always use the lowest pressure
needed to get the desired results.
b. If more coverage is needed, use a larger tip
rather than increasing the pressure.
c. Adjust the direction of the spray pattern. See
Fig. 8. Engage the gun safety latch. Loosen
the retaining nut (A). Position the tip guard for
a horizontal or vertical pattern. Hold the tip
guard in place and tighten the retaining nut.
NOTE: Spray patterns will change as tips wear .
Change the spray tip if adjusting the pressure will not
improve the spray pattern.
01025
Fig. 8
For a horizontal
spray pattern
For a vertical
spray pattern




A

308-634 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.
Shutdown and Care
1. Check the packing nut/wet-cup daily (102).
Relieve pressure first. 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. 9.
3. Periodically clean paint residue from the pres -
sure transducer (29) vent hole area. See Fig. 10.
Replace the transducer when leakage is exces -
sive. See page 30.
4. Lubricate the bearing housing after every 100
hours of operation. Remove the front cover . Fill the
bearing housing cavity (A) with SAE 10 non-
detergent oil. See Fig. 10.
5. 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.
To 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 sprayer or result in a loss of pressure or
stalling.
CAUTION
6. For very short shutoff periods, leave the suction
tube in the paint, relieve pressure, and clean the
spray tip.
7. Coil the hose and hang it on a hose rack when
storing it, even for overnight, to help protect the
hose from kinking, abrasion, coupling damage, etc.
INJECTION HAZARD
See the warning section INJECTION
HAZARD on page 3 for information on
the hazard of using damaged hoses.
WARNING
05117
Fig. 9
Turn packing
nut clockwise to
tighten

102
Fig. 10

Vent
hole
29
A

02827A

12 308-634
Flushing
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 min -
eral 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 a 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 mineral spirits, then 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 pressure. Leave
the drain valve open.
Storage after using oil-base paint: flush with
mineral spirits. Relieve pressure. Leave the drain
valve open.
CAUTION
Never allow water to freeze in the pressure control.
Doing so prevents the sprayer from being started
and may cause serious damage. Push the water out
with mineral spirits.
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. Follow the Pressure Relief Procedure on
page 9.
2. Remove the spray tip and clean it separately .
Remove the filter screen and then reinstall the
bowl, hand tight, without the screen. Clean the
screen separately .
3. Pour one-half gallon (2 liters) of compatible solvent
into a grounded metal flushing pail. Put the suction
hose in the pail.
4. Open the pressure drain valve. See Fig. 4, page
7.
5. To save the paint still in the pump and hose,
follow Step 6, except put the drain tube in the paint
pail. When solvent appears, close the drain valve.
Put the drain tube in the flushing pail. T rigger the
gun into the paint pail. When solvent appears,
release the trigger . Continue with Step 6.
T o reduce static sparking and splashing,
always remove the spray tip from the
gun, and hold a metal part of the gun
firmly to the side of a grounded metal pail when
flushing.
WARNING
FIRE AND EXPLOSION HAZARD
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 . Engage the gun
trigger safety .
7.
Open the drain valve and circulate the solvent
through the drain tube to thoroughly clean it. Close
the drain valve.
8. Remove the suction hose from the pail. Disengage
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
pressure.
9.
Remove and clean the inlet strainer . Wipe paint of f
the suction hose and drain tube.
10. Refer to When To Flush, Step 1 again. Relieve
pressure.
11.
Leave the drain valve open until you use the
sprayer again.

308-634 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.
Basic Problem Solving
Check everything in the troubleshooting table 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 308–429.
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. 17, page 21.
2. Push pin into place and secure with
spring retainer .
3. Check for motor damage. Remove drive hous -
ing assembly (1 1). See page 27. T ry to rotate
motor fan by hand.
3. Replace motor (4) if fan won’t turn. See
page 25.
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 26.
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 0.5 in.
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 21) and/or pressure transducer (page 30) must be replaced.

14 308-634
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 25.
6. Check motor armature for shorts using arma -
ture tester (growler) or perform motor test.
See page 17.
6. Replace motor . See page 25.
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 26.
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 26.
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 105–125V AC. Unplug sprayer .
9. Replace power supply cord. See page
26.
10. Check ON/OFF switch (52). Disconnect the
motor start board (47) and switch and connect
volt meter between exposed terminal on switch
and power cord’ s white wire. Plug in sprayer
and turn ON . Meter should read 105–125V AC
T
urn of f and unplug sprayer .
10. Replace ON/OFF switch. See page 26.
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 29.
13. Check pressure transducer (29) for hardened
paint or damaged or worn components. See
page 30.
13. Replace transducer . See page 30. 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 21.

 
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 21.
4. Check electrical supply with volt meter . Meter
should read 105–125V
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 12 gauge wire and less than 150 ft
(45 m) long.
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 26.
8. Check motor armature for shorts by using an
armature tester (growler) or perform motor test.
See page 17.
8. Replace motor . See page 25.
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 32.
Transducer leaks 1. Slight leakage from transducer is normal. 1. Periodically remove residue from its cyl -
inder port. See page 30.
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 31.
3. T ighten; use thread sealant on npt
threads of adapter (38).
4. Check to see if intake valve ball and piston ball
are seating properly . See page 21.
4. Remove intake valve and clean. Check
ball and seat for nicks; replace as need -
ed. See page 21. 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 21.
5. Replace packings. See page 21. 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 21.
No output: motor runs but
pump does not stroke
1. Check displacement pump connecting rod pin
(17). See Fig. 17, page 21.
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 27.
7. Replace connecting rod assembly . See
page 27.
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 27.
8. Check drive housing assembly for
damage and replace if necessary . See
page 27.

16 308-634
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 V ariations 1.
Spray tip worn beyond sprayer pressure capa -
bility.
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 30.
3. Check pressure control (64) for smooth opera -
tion.
3. Replace pressure control. See page 29.
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 90  F (32  C) and
sprayer is not located in direct sun.
2. Move sprayer to shaded, cooler area if
possible.
3. Check motor. 3. Replace motor . See page 25.
Building Circuit Breaker
Opens As Soon As
Sprayer Switch Is
T urned 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 25.
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 25.
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 26.
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
sprayer
is NOT turned on.
1. 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).
1. Replace ON/OFF switch. See page 26.
2. Check electrical supply with volt meter . Meter
should read 105–125 V
AC.
2. If voltage is too high, do not operate
sprayer until corrected.
Unit will not run on gener -
ator but does run on AC
power
Check the generator ’ s peak voltage. This sprayer will
not run if the peak voltage is above 190V .
Use AC power or a dif ferent generator

 
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 27. 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. 1 1.
Remove the junction box screws (56). Lower the
junction box. Disconnect the two leads (C) from the
motor to the board (47). See Fig. 12.
Armature Short Circuit Test
Remove the fan cover (B). See Fig. 1 1.
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 shorted and the motor must be re -
placed. See page 25.
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, or no 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 25.
Fig. 11
A
B
02829A
Fig. 12
MOTOR
BLACK/
WHITE
BLACK
C
59
RED
47
04720
56

18 308-634
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 the 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/off 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 jam nut
5/64” drive pin: drain valve pin
3” needle nose pliers: wiring, on/off switch
Hammer & punch: packing nut
T orque wrenches: various fasteners
WARNING
MOVING P ARTS HAZARD
T o reduce the risk of serious injury , in -
cluding electric shock, DO NOT touch
any moving parts or electrical parts with
your fingers or a tool while inspecting 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
HOT SURF ACE HAZARD
During operation, the motor and drive
housing become very hot and could burn
your skin if touched. Flammable materi -
als spilled on the hot, bare motor could cause a fire
or explosion
CAUTION
T o reduce the risk of a pressure control malfunc -
tion, 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.
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
Improper wire routing can result in poor sprayer
performance or damage to the pressure control.
3. Route wires carefully through the drive housing
and motor . A void pinching the wires between the
junction box and the motor or 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
the T roubleshooting Guide, pages 13–17, to help
identify other possible problems and solutions.

 
Motor Brushes
NOTE: Replace brushes when worn to about 0.5 in.
(12.5 mm). Always check both brushes. Brush Repair
Kit 236–967, which includes spring clip 1 12–766, is
available for motors manufactured by Pacific Scientific.
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 for at least
one hour with no load (remove the pump connecting
rod pin).
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. Remove both inspection covers (A) and their
gaskets. See Fig 13.
Fig. 13
A
02831A
2. Push in the spring clip (F) and release its hook (G)
from the brush holder (B). Pull out the spring clip.
See Fig 14.
3. Slide of f the brush lead terminal (E) of f the blade
connector . Remove the old brush (C). See Fig 14.
Fig. 14
F
G
E
D
C
B
H
1
1
Motor
lead; do not disconnect
2 Minimum 0.5” (12.5 mm)
03881
3
Included in Brush Repair
Kit 236–967
3
2
4. Inspect the commutator for excessive pitting,
burning or gouging. A black color on the commuta
-
tor 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 9.d.,
also.
5.
Repeat for the other side.
NOTE: The motor brushes on the other side are
upside down.
6. Place a new brush (C) in the holder (B) so the
ramp (H) faces the spring. See Fig. 16.
Fig. 15 03881
1
G
C
E
F
7.
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. 15. Pull on the
spring clip to be sure it stays in place. Connect the
brush lead to the blade connector (E).
8. Repeat for the other side.

 
Motor Brushes
9. Test the brushes.
a.
Remove the pump connecting rod pin (17).
See Fig. 17, page 21.
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 trail or
circle
around the commutator surface.
WARNING
MOVING P ARTS HAZARD
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 .
10. Install the brush inspection covers and gaskets.
11. Break in the brushes. Operate the sprayer for at
least one hour with no load. Install the pump
connecting rod pin. See Fig. 17, page 21.