Graco 231-373 Operation manual

308–619
Rev. D
Supersedes Rev. A
PCN B; unreleased
Rev. C
First choice when
quality counts. 
INSTRUCTIONS-PARTS LIST
INSTRUCTIONS
This manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
120 V AC, 15 AMP
ULTRA PLUS+ 1000
AIRLESS P AINT SPRA YER
3000 psi (210 bar , 21 MPa) Maximum Working Pressure
Model 231–373, Series A
Complete sprayer on Upright cart with hose,
gun, RAC IV  DripLess  T ip Guard
and SwitchT ip
U.S. P A TENT NO. 4,323,741; 4,397,610
PA TENTED 1983, CANADA
AND OTHER P A TENTS PENDING
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
http://www.graco.com
COPYRIGHT
1996, GRACO INC.
Graco Inc. is registered to I.S. EN ISO 9001
MODEL 231–373



Table of Contents
Introduction 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warnings 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Startup 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown and Care 11. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spin Test 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Repair Information 19. . . . . . . . . . . . . . . . . . . . .
Motor Brush Replacement 20. . . . . . . . . . . . . . . . . . . . .
Power Supply Cord Replacement 21. . . . . . . . . . . . . . .
On/Off Switch Replacement 22. . . . . . . . . . . . . . . . . . . .
Pressure Control Replacement 23. . . . . . . . . . . . . . . . .
Bearing Housing & Connecting Rod Replacement 25.
Drive Housing Replacement 26. . . . . . . . . . . . . . . . . . . .
Motor Replacement 28. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump Repair 30. . . . . . . . . . . . . . . . . . . . .
Parts Drawing – Sprayer 34. . . . . . . . . . . . . . . . . . . . . . .
Parts List – Sprayer 35. . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Drawing and List – Displacement Pump 36. . . . .
Parts Drawing – Pressure Control 37. . . . . . . . . . . . . . .
Parts List – Pressure Control 37. . . . . . . . . . . . . . . . . . .
Wiring Diagram 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Number 40. . . . . . . . . . . . . . . . . . . . . . . . . .
The Graco W arranty And Disclaimers 40. . . . . . . . . . . .
Introduction
ULTRA PLUS+ 1000 BASIC COMPONENTS
Your new sprayer functions and operates dif ferently than
other airless paint sprayers. This section will help you be -
come
familiar with the sprayer before operating it.
Pressure Control
The pressure control includes an ON/OFF switch for the
sprayer, a pressure adjusting control knob and a freeze
resistant pressure sensing device. The function of the
pressure
control is to control the motor speed so that the
sprayer maintains constant fluid pressure at the pump
outlet.
Pressure Drain V alve
The pressure drain valve provides pressure relief of the
sprayer.
In the forward position, the drain valve is closed
and allows normal sprayer operation. In the downward
position, the pressure drain valve relieves the pressure
in
the system. The pressure drain valve will also open au -
tomatically in the case of a control overpressure failure.
Motor
The DC motor has sealed bearings and replaceable mo -
tor brushes. It drives the displacement pump at the rate
needed
to supply suf ficient paint volume at the selected
pressure. W orking together , the pressure control and
motor
cause the pump to cycle whenever there is fluid or
pressure demand. When the pump is cycling, the motor
sounds like an automobile starter cranking. When the
pump
is not cycling, the motor may hum intermittently un -
til
the fluid pressure stabilizes, then the motor will shut it -
self off. However, there will still be power to the sprayer
and it will stay pressurized and ready to use until you
manually
shut it of f and relieve pressure.
Because the motor is DC, it is less sensitive to low volt-
age or voltage fluctuations than an AC motor, and a 12
gauge
or larger extension cord of up to 300 ft. (90 m) can
be used without performance loss.
Drive Assembly
The sealed drive assembly transfers power from the DC
motor to the displacement pump.
Displacement Pump
The positive displacement, volume-balanced pump pro -
vides
equal fluid delivery on both the up and down pump
strokes. The pump has a wet-cup which, when filled with
Graco Throat Seal Liquid, helps prevent damage to the
throat
packings and piston rod.
Fluid Filter
The fluid filter strains the paint to help avoid clogs in the
hose and spray tip. The filter includes a reusable element
and has a pressure drain valve for manually relieving fluid
pressure.
Hoses
The grounded, nylon spray hoses have spring guards on
both ends. The 50 ft. (15.2 m) hose has a 1/4 in. ID. The
3 ft. (0.9 m), 3/16 in. ID hose provides more flexible gun
movement. The nylon hose material acts as a pulsation
dampener to absorb pressure fluctuations.
Spray Gun & RAC IV DripLess Tip Guard
Graco high pressure spray guns have a safety latch
which
prevents accidental triggering when it is engaged.
See T in Fig. 1. The gun provided with the sprayer also
has
a filter for final paint straining. The Reverse-A-Clean
IV SwitchTip uses high pressure fluid to remove clogs
from
the spray tip without removing it from the gun. The
Reverse-A-Clean IV DripLess tip guard is a safety fea-
ture
which helps reduce the risk of fluid injection injury .



Fig. 1
J
S
P
E
F
D
A
C
T
G
K
L
R
0137
M
N
B
04239
H
AMotor
DC motor , 120 V ac, 15A, 1 phase
B Pressure Adjusting Knob Controls fluid outlet pressure
C ON/OFF Switch Power switch that controls 120 V ac main power to sprayer
D Drive Assembly T ransfers power from DC motor to the displacement pump
E Fluid Filter Final filter of fluid between source and spray gun
F Secondary Fluid Outlet Second spray gun operation is connected here
G Pail Hanger Container for fluid to be sprayed may be hung here
H Displacement Pump T ransfers fluid to be sprayed from source through spray gun
J 50 ft (15 m) Main Hose 1/4 in. ID, grounded, nylon hose with spring guards on both ends
K RAC IV T ip Guard Reverse-A-Clean (RAC) tip guard reduces the risk of injection injury
L Contractor Gun High pressure spray gun with gun safety latch
M RAC IV Switch T ip RAC switch tip uses high pressure fluid to remove clogs from spray
tip without removing tip from spray gun
N 3 ft (0.9 m) Hose 3/16 in. ID, grounded, nylon hose used between 50 ft hose and
spray gun to allow more flexibility when spraying
P Primary Fluid Outlet Single spray gun operation is connected here
R Pressure Drain V alve Relieves fluid outlet pressure when open
S Pressure Control Controls motor speed to maintain fluid outlet pressure at displace -
ment pump outlet. W orks with pressure adjusting knob.
T Spray Gun Safety Latch Gun safety latch inhibits accidental triggering of spray gun

4308-619
Symbols
Warning Symbol
WARNING
his 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.
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 39 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 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

5
308-619
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 .
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 13 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


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.
WARNING
WARNING
MOVING P ARTS HAZARD
Moving parts, such as the air motor piston, 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 13 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 trigger -
ing 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 liquids in
confined areas can result in fire or explosion.
Use outdoors or in extremely well ventilated areas. Ground equipment,
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 cigarettes, arcs from
connecting or disconnecting power cords or turning 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 39 to order .

7
308-619
Setup
WARNING
To reduce the risk of serious injury from static
sparking, injection, or over pressurization and
rupture
of the hose or gun, all hoses must be electri -
cally conductive, the gun must have a tip guard, and
each part must be rated for at least 3000 psi (210 bar)
Maximum W orking Pressure.
T o avoid damaging the pressure control, which may
result in poor equipment performance and compo-
nent
damage, follow these precautions:
1. Always use grounded, flexible 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 main hose. See Fig. 2.
4. Always use the main filter outlet for one gun op -
eration.
Never plug this outlet.
CAUTION
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. Read the warning sec -
tion FIRE OR EXPLOSION HAZARD on
page 6 for more detailed grounding
instructions.
WARNING
NOTE: See Fig. 2 while doing the setup.
1. Fill the packing nut/wet-cup 1/3 full with Graco
Throat Seal Liquid (TSL), supplied.
2. Connect the gun, 3 ft. hose and 50 ft. hose.
Screw the assembly onto the outlet nipple. Don’t
use thread sealant and don’t install the spray tip
yet!
3. Two gun hookup . Unscrew the cap from the 1/4
npsm(m) secondary hose outlet. Connect a hose
and gun to the outlet. Use a 1/4 in. ID, 50 ft. long
(minimum) main hose. For more flexible gun
movement, install a 3/16. ID, 3 ft. hose between
the main hose and the gun.
4. Check the Electrical Service.
Two gun hookup. Unscrew the cap from the 1/4
npsm(m) secondary hose outlet. Connect a hose
and gun to the outlet. Use a 1/4 in. ID, 50 ft. long
(minimum) main hose. For more flexible gun move-
ment,
install a 3/16 in. ID, 3 ft. hose between the main
hose and the gun.
a.
Electrical requirements: 120 V AC, 60 Hz, 15
Amp (minimum).
b. Use
a grounded electrical outlet located at least
20 ft. (6 m) from the spray area.
b. Do not remove the grounding prong of the power
supply cord and do not use an adapter .
c. Extension
cord specifications: 15 Amps, 3 wires,
grounding type. (Long lengths reduce sprayer
performance.)
5. Plug
in the sprayer. T urn the ON/OFF switch
OFF . Plug the cord into a grounded electrical
outlet.
6. Flush the pump
to remove the oil left in to protect
pump parts after factory testing. See Flushing
on page 12.
7. Prepare the paint according to the manufacturer ’s
recommendations. Remove any paint skin. Stir the
paint thoroughly . Strain the paint through a fine
nylon mesh bag (available at most paint dealers)
to remove particles that could clog the filter or
spray tip. This is an important step for trouble-free
paint spraying.


Setup
ON/OFF SWITCH
1/4 npsm(m) FLUID OUTLET NIPPLE
DO NOT INST ALL ANY SHUT OFF
DEVICE HERE
PRESSURE ADJUSTING KNOB
PRESSURE
DRAIN
VALVE
P ACKING NUT/ WET–CUP
FILL 1/3 FULL WITH TSL
Fig. 2




Startup
Use this procedure each time you start the sprayer to
help
ensure the sprayer is ready to operate and that you
start it safely .
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
follow the illustrated Pressure Relief
Procedure warning on page 13 when -
ever you are instructed to relieve pressure.
NOTE: Flush the sprayer if this is a first-time startup.
See page 12.
NOTE: See Fig. 4 except where noted.
1. Put the suction tube into the paint container.
2. Turn the pressure adjusting knob fully coun-
terclockwise to zero pressure.
3. Plug in the sprayer .
CAUTION
Do not run the pump without fluid in it for more than
30 seconds to avoid damage to the displacement
pump
packings.
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 a
grounded metal pail.
WARNING
FIRE AND EXPLOSION HAZARD
4. Prime the pump .
a. Open the pressure drain valve (handle in down -
ward position). If you did not install a secondary
hose, be sure the nipple is tightly plugged with
the cap provided. T urn the ON/OFF switch to
ON. Slowly turn the pressure adjusting knob
clockwise until the sprayer starts. When fluid
comes
from the drain hose, close the valve (han -
dle
in forward position).
b. Disengage the gun safety latch. See Fig. 3.
Following the warning, above, trigger the gun
until all air is forced out of the system and the
paint
flows freely from the gun.
c. Release the trigger . Engage the gun safety latch.
5. Check all fluid connections for leaks . Relieve
the fluid pressure before tightening connections.
6. Install the spray tip and tip guard. Engage the
gun safety latch. See Fig. 3. Install the spray tip
according to the instructions supplied with it.
7. Adjust the spray pattern.
a. Increase the pressure just until spray from the
gun is completely atomized. Use the lowest
pressure
needed to get the desired results. This
reduces overspray and fogging, decreases tip
wear
and extends the life of the sprayer .
b. If more coverage is needed, use a larger tip
rather
than increasing the pressure.
c. Test the spray pattern. T o adjust the pattern,
engage
the gun safety latch, loosen the retaining
nut. Position the tip guard horizontally for a hori -
zontal pattern or vertically for a vertical pattern.
Then
tighten the retaining nut.
0137
GUN SAFETY
LA TCH SHOWN
ENGAGED
GUN SAFETY LA TCH
SHOWN DISENGAGED
Fig. 3
ON/OFF SWITCH
OUTLET NIPPLE
PRESSURE ADJUSTING KNOB
PRESSURE
DRAIN
VALVE
DRAIN HOSE
Fig. 4
04243

 
Startup
Cleaning a Clogged Tip
WARNING
FLUID INJECTION HAZARD
T o reduce the risk of serious injury ,
follow the illustrated Pressure Relief
Procedure warning on page 13 when -
ever you are instructed to relieve pressure.
1. Clean the front of the tip frequently during the day’s
operation. First, relieve pressure.
2. If the spray tip does clog, release the gun trigger , en -
gage the gun safety latch, and rotate the RAC IV
handle
180  . See Fig. 5.
3. Disengage the gun safety latch and trigger the gun
into a waste container. Engage the gun safety latch
again.
4. Return the handle to the original position, disengage
the gun safety latch, and resume spraying.
5. If the tip is still clogged, engage the gun safety latch,
shut of f and unplug the sprayer , and open the pres-
sure
drain valve to relieve pressure. Clean the spray
tip as shown in manual 307–848, supplied with the
RAC
IV .

GUN SAFETY
LA TCH SHOWN
ENGAGED
TIP GUARD HANDLE
SHOWN IN SPRA YING
POSITION
TURN HANDLE 180 ,
DISENGAGE SAFETY
LATCH AND TRIGGER
GUN TO CLEAR CLOG
Fig. 5



Shutdown and Care
WARNING
FLUID INJECTION HAZARD
T o reduce the risk of serious injury ,
follow the illustrated Pressure Relief
Procedure warning on page 13 when -
ever you are instructed to relieve pressure.
1. Check the packing nut/wet-cup daily . First relieve
pressure. 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.
Tighten the packing nut just enough to stop leakage.
Over tightening causes binding and excessive pack -
ing wear. Use a round punch or brass rod and light
hammer
to adjust the nut. Refer to Fig. 6.
2. Clean the fluid filter often and whenever the spray -
er
is stored. Follow the Flushing Guidelines on page
12 or refer to manual 307–273, supplied, for the
cleaning
procedure.
3. Lubricate the bearing housing after every 100
hours of operation. First relieve pressure. Remove
the front cover. Fill the bearing housing cavity with
SAE
10 non-detergent oil. See Fig. 7.
4. For very short shutoff periods, leave the suction
tube in the paint, relieve pressure, and clean the
spray
tip.
5. Flush the sprayer at the end of each work day and
fill it with mineral spirits to help prevent pump corro -
sion
and freezing. See page 12.
To prevent pump corrosion, never leave water or any
type of paint in the sprayer when it is not in use. Pump
water or paint out with mineral spirits.
CAUTION
6. Coil the hose and hang it on the hose rack when
storing
it, even for overnight, to help protect the hose
from kinking, abrasion, coupling damage, etc.
PACKING NUT/
WET–CUP
TIGHTEN
Fig. 6

FILL BEARING HOUSING
CA
VITY WITH SAE
NON-DETERGENT OIL
AFTER EVER Y 100
HOURS OF OPERATION
FRONT
COVER
Fig. 7


 
Flushing
NOTE: Several flushes are often required to thoroughly clean the system and prepare it for the next fluid to be
sprayed, or to store the sprayer . Use this chart to determine the required flushing order for the fluid you are
using, and then follow the procedure below for flushing.
*Use this category for flushing a brand new sprayer and flushing after storage.
System has
this fluid in it:
Next fluid to be
sprayed
Flushing order:
Before you spray or store
sprayer:
this fluid in it: sprayed.
Flush 1 Flush 2 Flush 3
sprayer:
*Oil-based
solvent or paint
Oil-based paint –
new color
Mineral spirits none none Prime with oil-based paint
Oil-based
solvent or paint
W ater-based paint Mineral spirits W arm soapy
water
Clean water Prime with water-based
paint
Oil-based
solvent or paint
Prepare for
storage
Mineral spirits none none Relieve pressure,
Leave drain valve open
Water or water-
based paint
W ater-based paint
– new color
W arm soapy
water
Clean water none Prime with water
Water or water-
based paint
Oil-based paint W arm soapy
water
Clean water Mineral spirits Prime with oil
Water or water-
based paint
Prepare for
storage
W arm soapy
water
Clean water Mineral spirits Relieve pressure,
Leave drain valve open
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 a
grounded metal pail.
WARNING
FIRE AND EXPLOSION HAZARD
1. Follow the illustrated Pressure Relief Procedure
on page 13. Engage the gun safety latch.
2. T urn the pressure adjusting knob fully counter -
clockwise to zero pressure.
3. Remove the spray tip from the gun. Remove the
filter bowl and screen; see manual 307–273. Clean
the screen separately and install the bowl without
the screen to flush it. See Fig. 8.
4. Put the suction tube into a grounded metal pail
with 1/2 gallon of compatible solvent.
5. Start the sprayer . See page 9. T o save the fluid
still in the sprayer , trigger the gun into another
container until the next fluid appears, then trigger
the gun back into the fluid you are pumping. Circu -
late the flushing fluid a couple of minutes to thor -
oughly clean the system.
6. Do not run the pump dry for more than 30 seconds
to avoid damaging the pump packings!
7. Follow the illustrated Pressure Relief Procedure
on page 13. Engage the gun safety latch.
8. Unscrew the filter bowl and reinstall the clean
screen. Install the bowl and hand tighten.
9. Remove the suction tube and screen and clean
them separately .
PRESSURE
DRAIN
V ALVE
FILTER
BOWL
SCREEN
FIL
TER
SUPPORT
Fig. 8


13
308-619
Troubleshooting
Pressure Relief Procedure
To reduce the risk of serious bodily injury , including fluid in -
jection,
splashing fluid or solvent in the eyes or on the skin,
or injury from moving parts or electric shock, always follow
this procedure whenever you shut of f the sprayer , when
checking or servicing any part of the spray system, when in -
stalling, cleaning or changing spray tips, and whenever you
stop spraying.
1. Engage the gun safety latch.
2. Turn 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 the side of a grounded metal pail, and trig -
ger the gun to relieve pressure.
5. Engage the gun safety latch.
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 fol -
lowing the steps above, VER Y SLOWL Y loosen the tip guard
retaining nut or hose coupling to relieve pressure gradually ,
then
loosen completely . Now clear the tip or hose.
1,5 2 4 6 3
Perform all Troubleshooting procedures before disassembling the sprayer .
MOTOR WON’T OPERATE
TYPE OF PROBLEM
WHAT 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
Basic Fluid Pressure Problems
1. Check the pressure control knob setting. The
motor will not run if it is at the minimum setting
(fully counterclockwise).
1. Slowly increase the pressure setting to see
if the motor starts.
2. Check for a clogged spray tip or fluid filter . Re -
fer to the separate gun, tip, or fluid filter in-
struction
manual.
2. Relieve pressure, refer to the separate gun,
tip, or fluid filter instruction manual for
cleaning.
Basic Mechanical Problems 1. Check for frozen or hardened paint in the
pump
(76) and/or pressure control tube. Using
a screwdriver , carefully try to rotate fan at back
of motor by hand. See page 18.
1. Thaw. Plug in sprayer and turn on. Slowly
increase pressure setting to see if motor
starts.
If it doesn’t, see NOTE 1, below .
2. Check displacement pump connecting rod pin
(43). It must be completely pushed into con-
necting rod (68) and retaining spring (42) must
be firmly in groove of connecting rod. See Fig.
32.
2. Push pin into place and secure with spring
retainer.
3. Check for motor damage. Remove drive
housing assembly (67). See page 26. T ry to
rotate
fan by hand.
3. Replace motor (73) if fan won’t turn. See
page
28.
Basic Electrical Problems 1. Check pressure control safety circuit. 2. Turn pressure control ON/OFF switch to
OFF
to RESET . If the pressure control safe -
ty continues to trip, see ELECTRICAL
SHORT
on page 17.
2. Check electrical supply with volt meter . Meter
should read 105–125 V AC.
2. Reset building circuit breaker; replace
building
fuse. T ry another outlet.
3. Check extension cord for damage. Check ex -
tension
cord continuity with a volt meter .
3. Replace extension cord.
4. Check sprayer power supply cord (314) for
damage
such as broken insulation or wires.
4. Replace power supply cord. See page 21.
5. Check motor brush leads, terminals and brush
length. Brush length should be 1/2” minimum.
See page 20.
5. Tighten terminal screws; replace brushes.
See
page 20.
NOTE 1: Thaw the sprayer if water or water-based paint has frozen in it, due to exposure to low temperatures, by placing it in a warm
area. Do not try to start the sprayer until it has thawed completely . If paint hardened (dried) in the sprayer , the pump packings and/or
pressure control must be replaced. See page 30 ( Displacement Pump ) or 23 ( Pressure Control).

14 308-619
MOTOR WON’T OPERATE (Continued)
TYPE OF PROBLEM
WHAT 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
Follow Pressure Relief
Procedure on page 13.
Remove gun from hose.
Remove pressure control.
1 . Check leads from motor to be sure they are
securely
fastened and properly mated.
1. Replace loose terminals; crimp to leads. Be
sure male terminal blades are straight and
firmly connected to mating part.
Clean circuit board male terminals. Re-
place loose or damaged terminals. Se-
curely
reconnect leads.
2. Check for loose motor brush lead connections
and terminals. See page 20.
2. Tighten terminal screws. Replace brushes
if leads are damaged. See page 20.
3. Check brush length which should be 1/2” mini -
mum.
See page 20.
NOTE: The brushes do not wear at the same
rate on both sides of the motor . Check both
brushes.
3. Replace brushes. See page 20.
4. Check for broken or misaligned motor brush
springs. Rolled portion of spring must rest
squarely
on top of brush. See page 20.
4. Replace spring if broken. Realign spring
with
brush. See page 20.
5. Check motor brushes for binding in brush
holders.
See page 20.
5. Clean brush holders. Remove carbon with
small cleaning brush. Align brush leads
with slot in brush holder to assure free verti -
cal brush movement.
6. Check motor armature commutator for burn
spots, gouges and extreme roughness. Re-
move motor cover and brush inspection
plates
to check. See page 20.
6. Remove motor and have motor shop resur -
face
commutator if possible. See page 28.
7. Check motor armature for shorts using arma -
ture
tester (growler) or perform spin test. See
page 18.
7. Replace motor . See page 28.
8. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 23.
8. Replace with new pressure control board
(301).
See page 23.
Refer to the wiring diagram
on page 38 to identify test
points (TP).
1. Check power supply cord (314). Disconnect
TP1 female (neutral) and TP2 female and
connect volt meter to these leads. Plug in
sprayer. Meter should read 105 to 125 V AC.
Unplug sprayer
. Reconnect TP2.
1. Replace power supply cord. See page 21.
2. Check ON/OFF switch (307). Disconnect TP3
and connect volt meter to TP1 female and TP3
male terminal on the ON/OFF switch. Plug in
sprayer and turn ON. Meter should read 105
to 125 V AC. T urn of f and unplug sprayer . Re -
connect
TP3.
2. Replace ON/OFF switch. See page 22.
3. Check motor terminal cutoff switch. Connect
volt meter to TP1 female and TP4 female.
Plug
in sprayer and turn on. Meter should read
105 to 125 V AC. T urn of f and unplug sprayer .
3. Allow motor to cool. Correct cause of over -
heating. If switch remains open after motor
cools, check continuity between TP4 fe-
male and TP5 female with ohmmeter . If
open,
replace motor .
4. Check all terminals for damage or loose fit.
Reconnect
TP1, TP4, and TP5 connectors.
4. Replace damaged terminals and recon-
nect securely.

15
308-619
LOW OUTPUT
TYPE OF PROBLEM
WHAT 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 W arn-
ing
then replace tip. See your separate gun
or tip manual.
2. Check to see that pump does not continue to
stroke when gun trigger is released. Plug in
and turn on sprayer . Prime with paint. T rigger
gun momentarily, then release and engage
safety
latch. Relieve pressure, turn of f and un -
plug sprayer.
2. Service pump. See pages 30–33.
3. Check electrical supply with volt meter . Meter
should read 105–125 V AC.
3. Reset building circuit breaker; replace
building
fuse. Repair electrical outlet or try
another outlet.
4. Check extension cord size and length; must
be
at least 12 gauge wire and no longer than
300 ft.
4. Replace with a correct, grounded exten-
sion
cord.
5. Check +, –, M+ and M– leads from motor to
pressure control circuit board (B1) for dam-
aged or loose wires or connectors. Inspect
wiring insulation and terminals for signs of
overheating.
See page 28.
5. Be sure male terminal blades are centered
and firmly connected to female terminals.
Replace any loose terminal or damaged
wiring. Securely reconnect terminals.
6. Check for loose motor brush leads and termi -
nals.
See page 20.
6. Tighten terminal screws. Replace brushes
if leads are damaged. See page 20.
7. Check for worn motor brushes which should
be
1/2” minimum. See page 20.
7. Replace brushes. See page 20.
8. Check for broken and misaligned motor brush
springs. Rolled portion of spring must rest
squarely on top of brush.
8. Replace spring if broken. Realign spring
with
brush. See page 20.
9. Check motor brushes for binding in brush
holders.
See page 20.
9. Clean brush holders, remove carbon dust
with
small cleaning brush. Align brush lead
with slot in brush holder to assure free verti -
cal brush movement.
10.Check stall pressure. 10.Replace with new pressure control board
(301).
See page 23.
11. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 23.
11. Replace with new pressure control board
(301).
See page 23.
12.Check motor armature for shorts by using an
armature tester (growler) or perform spin test.
See page 18.
12. Replace motor . See page 28.

 
NO OUTPUT
TYPE OF PROBLEM
WHAT 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
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. 3. Tighten; use thread sealant or sealing tape
on threads if necessary.
4. Check to see if intake valve ball and piston ball
are seating properly . See page 30.
4. Remove intake valve and clean. Check
balls
and seats for nicks; replace if neces -
sary. See page 30. Strain paint before us-
ing to remove particles that could clog the
pump.
5. Check for leaking around throat packing nut
which may indicate worn or damaged pack-
ings.
See page 30.
5. Replace packings. See pages 30–33. Also
check piston valve seat for hardened paint
or nicks and replace if necessary. Tighten
the packing nut/wet-cup.
Motor runs but pump does not
stroke
1. Check displacement pump connecting rod pin
(43). See page 32.
1. Replace pin if missing. Be sure retainer
spring
(42) is fully in groove all around con -
necting rod. See page 32.
2. Check connecting rod assembly (68) for dam -
age.
See page 25.
2. Replace connecting rod assembly . See
page
25.
3. Be sure crank in drive housing rotates; plug in
sprayer and turn on briefly to check. Turn off
and unplug sprayer . See page 26.
3. Check drive housing assembly for damage
and replace if necessary . See page 26.
EXCESSIVE PRESSURE FLUCTUA TIONS
TYPE OF PROBLEM
WHAT 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. Be sure leads to pressure control circuit board
(B1) are firmly connected. Be sure all male ter -
minals blades are centered and firmly con-
nected
to female terminals. See Fig. 33.
1. Reconnect securely . See Fig. 33.
2. Check maximum working pressure. 2. Replace with a new pressure control board
(301). See page 23.
3. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 23.
3. Replace with a new pressure control board
(301). See page 23.
4. Check LOW OUTPUT section, page 15.

17
308-619
MOTOR IS HOT AND RUNS INTERMITTENTLY
TYPE OF PROBLEM
WHAT 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
Motor is hot and runs intermit-
tently.
1. Determine if sprayer was operated at high
pressure with small tips, which causes low
motor
RPM and 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 and sprayer
is
not located in direct sun.
2. Move sprayer to shaded, cooler area if pos -
sible.
3. Determine if sprayer was turned on, pressur -
ized,
but not operating for long periods of time.
3 Turn of f sprayer whenever you stop spray -
ing
for a while and relieve fluid pressure.
ELECTRICAL SHORT
TYPE OF PROBLEM
WHAT 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
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 which are encased in conduit (1).
See
page 28.
1. Repair or replace any damaged wiring or
terminals.
Securely reconnect all wires.
2. Check for missing inspection plate gasket
(see page 28), 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 ar-
mature tester (growler) or perform spin test.
See
page 18. Inspect windings for burns.
3. Replace motor . See page 28.
4. Check pressure control board (301) by substi -
tuting
with a good control board. See page 23.
4. Replace with a new pressure control board
(301). See page 23.
1. Check Basic Electrical Problems on page 13. 1. Perform necessary procedures.
2. Check ON/OFF switch (307) See page 22. Be
sure the sprayer is unplugged!
Disconnect
wires from switch. Check switch with ohmme -
ter.
The reading should be infinity with the ON/
OFF switch OFF , and zero with the switch ON.
2. Replace ON/OFF switch. See page 22.
3. Check for damaged or pinched wires in the
pressure
control. See page 23.
3. Replace damaged parts. See page 23.
Sprayer quits after sprayer op -
erates
for 5 to 10 minutes.
1. Check Basic Electrical Problems on page 13. 1. Perform necessary procedures.
2. Check electrical supply with volt meter . Meter
should read 105 to 125 V AC.
2. If voltage is too high, do not operate
sprayer until corrected.
3. Check tightness of pump packing nut. Over-
tightening tightens packings on rod, restricts
pump
action, and damages packings.
3. Loosen packing nut. Check for leaking
around throat. Replace pump packings, if
necessary.
See page 30.

 
Spin T est
WARNING
ELECTRIC SHOCK 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 bodily injury .
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
follow the illustrated Pressure Relief
Procedure warning on page 13 when -
ever you are instructed to relieve pressure.
For checking armature, motor winding and brush electri -
cal
continuity .
Setup
Relieve pressure. Remove the drive housing. See page
26.
Remove
the motor shield (59), the fan cover (F) and the
inspection covers (J). See Fig. 9.
Remove the pressure control/cover(301). Disconnect
the
– and + leads from the motor to the pressure control/
cover terminals M–, and M+. See Fig. 10.
Armature Short Circuit Test
Relieve pressure. Quickly turn the motor fan by hand. If
there
are no shorts, the motor will coast two or three revo -
lutions before coming to a complete stop. If the motor
does
not spin freely , the armature is shorted and the mo -
tor
must be replaced. See page 28.
Fig. 9 J
F
59
01224A
Armature, Brushes, and Motor Wiring Open
Circuit Test (Continuity)
Relieve pressure. Connect the two black motor leads to -
gether with a test lead. T urn the motor fan by hand at
about
two revolutions per second.
If there is uneven or no turning resistance, check the fol -
lowing:
broken brush springs, brush leads, motor leads;
loose brush terminal screws, motor lead terminals; worn
brushes. Repair parts as needed. See page 20.
If there is still uneven or no turning resistance, replace the
motor. See page 28.
04790
M–
M+
+
–
Fig. 10
301



General Repair Information
To reduce the risk of a pressure control malfunction:
Always use needle nose pliers to disconnect a
wire.
Never pull on the wire, pull on the connec -
tor.
Mate wire connectors properly. Be sure the flat
blade
of the insulated male connector is centered
in the wrap-around blade of the female connec-
tor.
Route wires carefully to avoid interference with
the
other connections of the pressure control. Be
sure the wires are not pinched between the cover
and the control box.
CAUTION
Phillips screwdriver
Small flat blade
screwdriver
Needle nose pliers
Plastic mallet
Adjustable wrench
Adjustable, open-end
wrench
T orque wrench
1/4 in. hex key wrench
3/16 in. hex key wrench
5/8 in. socket wrench
3/8 in. open end wrench
1/2 in. open end wrench
3/4 in. open end wrench
7/8 in. open end wrench
High quality motor oil
Bearing grease
Tool List
1. Keep all screws, nuts, washers, gaskets, and
electrical fittings removed during repair proce -
dures. These parts are not normally provided with
replacement assemblies.
2. T est your repair before regular operation of the
sprayer to be sure the problem is corrected.
WARNING
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, gas -
kets, screws and washers before operating the
sprayer.
ELECTRIC SHOCK HAZARD
3. If the sprayer does not operate properly , review
the repair procedure again to verify that everything
was done correctly. If necessary, see the
T roubleshooting Guide, pages 13 – 17, to help
identify other possible problems and solutions.
CAUTION
Do not run the sprayer dry for more than 30 sec -
onds to avoid damaging the pump packings.
4. Reinstall the motor shield before regular op -
eration of the sprayer and replace it if it is dam -
aged. The cover directs cooling air around the
motor to help prevent overheating. It can also help
reduce the risk of burns, fire or explosion; see the
WARNING, below .
WARNING
FIRE AND EXPLOSION HAZARD
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. Always have the motor
shield in place during regular operation to reduce
the risk of burns, fire or explosion.

 
Motor Brush Replacement
NOTE: Replace the brushes when they have worn to
less
than 1/2 in. Note that the brushes wear dif -
ferently
on each side of the motor , so check them
both. Brush Repair Kit 220–853 is available. A
new
spring clip, P/N 1 10–816 may be purchased
separately.
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury ,
follow the illustrated Pressure Relief
Procedure warning on page 13 when -
ever you are instructed to relieve pressure.
NOTE: Read the GENERAL REP AIR INFORMATION
on
page 19 before doing this procedure.
1. Relieve pressure.
2. Remove the motor shield (59). Remove the in -
spection covers (J) and gaskets (K) on each side
of the motor . See Fig. 1 1.
J
F
59
Fig. 11 01224A
3. Push in the spring clip to release its hooks from
the brush holder . Pull out the spring clip. See Fig.
12.
Fig. 12
BRUSH
SPRING CLIP
P/N 1
10–816
HOOK
SPRING
01227
4. Loosen the brush lead terminal screw . Pull the
brush lead away , leaving the motor lead terminal in
place. Remove the brush and spring. See Fig. 14.
5. 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.
CAUTION
When installing the brushes, follow all steps care -
fully to avoid damaging the parts.
6. Install a new brush so the lead is in the long slot of
the holder . See Fig. 13.
Fig. 13
BRUSH
SHORT
SLOT
LONG SLOT
BRUSH HOLDER
NOTE: SPRING MUST COIL
IN THIS DIRECTION
SPRING
CLIP
01227
7. Slide the terminal under the terminal screw washer
and tighten the screw. Be sure the motor lead is
still connected at the screw . See Fig. 14.
Fig. 14
SPRING
BRUSH LEAD
TERMINAL SCREW
MOT OR LEAD
TERMINAL
BRUSH
SPRING CLIP
01227
8. Place the spring on the brush as shown in Fig. 13.
9. Install the spring clip and push it down to hook the
short slots in the housing. See Fig. 13.
10. Repeat for the other side.