Graco ULTRA PLUS+ 750 Operation manual

308–712
Rev. B
Supersedes Rev. A
First choice when
quality counts. 
INSTRUCTIONS-PARTS LIST
INSTRUCTIONS
This manual contains important
warnings and information.
READ AND KEEP FOR REFERENCE.
120 V AC, 13.8A
ULTRA PLUS+ 750 Lo-Boy
AIRLESS P AINT SPRA YER
3000 psi (210 bar , 21 MPa) Maximum Working Pressure
Model 231–574 Series A
Complete sprayer on Lo-Boy cart with hose,
gun, RAC IV  DripLess  T ip Guard
and SwitchT ip
Related Manuals
Displacement Pump 307–806. . . . . . . . . . . . . . . . . . . . . .
Fluid Filter 307–273. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spray Gun 307–614. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spray Tip 308–644. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
http://www.graco.com
COPYRIGHT
1997, GRACO INC.
Graco Inc. is registered to I.S. EN ISO 9001

MODEL 231–574

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Table of Contents
Warnings 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Startup 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown and Care 10. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spin Test 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Repair Information 18. . . . . . . . . . . . . . . . . . . . .
Motor Brush Replacement 19. . . . . . . . . . . . . . . . . . . . .
Power Supply Cord Replacement 20. . . . . . . . . . . . . . .
On/Off Switch Replacement 21. . . . . . . . . . . . . . . . . . . .
Pressure Control Replacement 22. . . . . . . . . . . . . . . . .
Bearing Housing & Connecting Rod Replacement 24.
Drive Housing Replacement 25. . . . . . . . . . . . . . . . . . . .
Motor Replacement 27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displacement Pump Repair 29. . . . . . . . . . . . . . . . . . . . .
Parts Drawing – Sprayer 30. . . . . . . . . . . . . . . . . . . . . . .
Parts List – Sprayer 31. . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Drawing – Pressure Control 32. . . . . . . . . . . . . . .
Parts List – Pressure Control 32. . . . . . . . . . . . . . . . . . .
Wiring Diagram 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Technical Data 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Number 36. . . . . . . . . . . . . . . . . . . . . . . . . .
The Graco W arranty And Disclaimers 36. . . . . . . . . . . .
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.
WARNING
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 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.
 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.
 Use only with a grounded outlet that matches the grounded plug of this equipment.

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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 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 8 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 .
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 8 to prevent the
equipment from starting unexpectedly .


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 34 for the maximum working pressure of this equipment.
 Use fluids and solvents which are compatible with the equipment wetted parts. Refer to the Tech-
nical 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 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.
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
triggering 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.
A void 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 34 to order .

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06985A
Fig. 1
K
S
P
E
D
A
C
T
J
LR
0137
MN
B
H
Component Identification and Function
AMotor DC motor , 120 VAC, 13.8A, 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
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


Setup
WARNING
T o reduce the risk of serious injury from static
sparking, injection, or over pressurization and
rupture of the hose or gun, all hoses must be
electrically conductive, the gun must have a tip
guard, and each part must be rated for at least
3000 psi (210 bar
, 21 MPa) Maximum W orking
Pressure.
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 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 shutoff device between the filter
and
the main hose. See Fig. 3.
4. Always use the main filter outlet for one gun opera -
tion.
Never plug this outlet.
WARNING
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
section FIRE OR EXPLOSION HAZ -
ARD
on page 2 for more detailed
grounding instructions.
NOTE: See Fig. 3 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. Grounding
WARNING
Improper installation or alteration of the grounding
plug will result in a risk of electric shock, fire or
explosion that could cause serious injury or death.
a. This equipment requires a 120 V ac, 60 Hz,
15A circuit with a grounding receptacle. See
Fig. 2.
Fig. 2
Grounding Prong
Grounded
Outlets
b. Do not alter the ground prong or use an adapt -
er.
c.
A 12 A WG gauge, 50 ft extension cord may be
used with this equipment.
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 1 1.
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.

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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. 3


Startup
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.
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 .
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 8.
NOTE: Flush the sprayer if this is a first-time startup.
See page 1 1.
NOTE:
See Fig. 5 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 sprayer dry for more than 30 seconds
to avoid damaging the pump packings.
WARNING
FIRE AND EXPLOSION HAZARD
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.
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. 4.
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.



Startup
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. 4. 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. 4
06986A
ON/OFF SWITCH
OUTLET NIPPLE
PRESSURE ADJUSTING KNOB
PRESSURE
DRAIN
VALVE
DRAIN HOSE
Fig. 5
Cleaning a Clogged Tip
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 8.
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. 6.
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 308–644, supplied with the
RAC
IV .
0137
GUN SAFETY
LATCH
SHOWN
ENGAGED
TIP GUARD HANDLE
SHOWN IN SPRA YING
POSITION
TURN HANDLE 180 ,
DISENGAGE SAFETY
LATCH AND TRIGGER
GUN TO CLEAR CLOG
Fig. 6

 
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 8.
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. 7.
2. Clean the fluid filter often and whenever the spray -
er
is stored. Follow the Flushing Guidelines on page
11 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. 8.
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 1 1.
CAUTION
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.
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. 7

FILL BEARING HOUSING
CA
VITY WITH SAE
NON-DETERGENT OIL
AFTER EVER Y 100
HOURS OF OPERATION
FRONT
COVER
Fig. 8



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
WARNING
FIRE AND EXPLOSION HAZARD
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.
1. Follow the illustrated Pressure Relief Procedure
on page 12. 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. 9.
4. Put the suction tube into a grounded metal pail
with 1/2 gallon of compatible solvent.
5. Start the sprayer . See page 8. 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 8. 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. 9
04248A

 
Troubleshooting
WARNING
INJECTION HAZARD
T o reduce the risk of serious injury, whenever you are instructed to relieve pressure, follow the Pres-
sure Relief Procedure on page 8.
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 17.
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.
25.
2. Push pin into place and secure with spring
retainer.
3. Check for motor damage. Remove drive
housing assembly (67). See page 25. T ry to
rotate
fan by hand.
3. Replace motor (73) if fan won’t turn. See
page
27.
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 16.
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 20.
5. Check motor brush leads, terminals and brush
length. Brush length should be 1/2” minimum.
See page 19.
5. Tighten terminal screws; replace brushes.
See
page 19.
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 manual 307–806 ( Displacement Pump ) or page 22 ( Pressure Control).



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 Pro -
cedure on page 13. Remove
gun from hose. Remove pres -
sure 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 19.
2. Tighten terminal screws. Replace brushes
if leads are damaged. See page 19.
3. Check brush length which should be 1/2” mini -
mum.
See page 19.
NOTE: The brushes do not wear at the same
rate on both sides of the motor . Check both
brushes.
3. Replace brushes. See page 19.
4. Check for broken or misaligned motor brush
springs. Rolled portion of spring must rest
squarely
on top of brush. See page 19.
4. Replace spring if broken. Realign spring
with
brush. See page 19.
5. Check motor brushes for binding in brush
holders.
See page 19.
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 19.
6. Remove motor and have motor shop resur -
face
commutator if possible. See page 27.
7. Check motor armature for shorts using arma -
ture
tester (growler) or perform spin test. See
page 17.
7. Replace motor . See page 27.
8. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 22.
8. Replace with new pressure control board
(301).
See page 22.
Refer to the wiring diagram
on page 33 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 20.
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 21.
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.

 
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 page 29 and manual
307–806.
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 27.
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 19.
6. Tighten terminal screws. Replace brushes
if leads are damaged. See page 19.
7. Check for worn motor brushes which should
be
1/2” minimum. See page 19.
7. Replace brushes. See page 19.
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 19.
9. Check motor brushes for binding in brush
holders.
See page 19.
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 22.
11. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 22.
11. Replace with new pressure control board
(301).
See page 22.
12.Check motor armature for shorts by using an
armature tester (growler) or perform spin test.
See page 17.
12. Replace motor . See page 27.



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 manual 307–806.
4. Remove intake valve and clean. Check
balls
and seats for nicks; replace if neces -
sary.
See manual 307–806. Strain paint be -
fore using 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 manual 307–806.
5. Replace packings. See manual 307–806.
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 manual 307–806.
1. Replace pin if missing. Be sure retainer
spring
(42) is fully in groove all around con -
necting rod. See manual 307–806.
2. Check connecting rod assembly (68) for dam -
age.
See page 24.
2. Replace connecting rod assembly . See
page
24.
3. Be sure crank in drive housing rotates; plug in
sprayer and turn on briefly to check. Turn off
and unplug sprayer . See page 25.
3. Check drive housing assembly for damage
and replace if necessary . See page 25.
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. 26.
1. Reconnect securely . See Fig. 26.
2. Check maximum working pressure. 2. Replace with a new pressure control board
(301). See page 22.
3. Check pressure control board (301) by substi -
tuting
with a good pressure control board. See
page 22.
3. Replace with a new pressure control board
(301). See page 22.
4. Check LOW OUTPUT section, page 14.

 
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 27.
1. Repair or replace any damaged wiring or
terminals.
Securely reconnect all wires.
2. Check for missing inspection plate gasket
(see page 27), 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 17. Inspect windings for burns.
3. Replace motor . See page 27.
4. Check pressure control board (301) by substi -
tuting
with a good control board. See page 22.
4. Replace with a new pressure control board
(301). See page 22.
1. Check Basic Electrical Problems on page 12. 1. Perform necessary procedures.
2. Check ON/OFF switch (307) See page 21. 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 21.
3. Check for damaged or pinched wires in the
pressure
control. See page 22.
3. Replace damaged parts. See page 22.
Sprayer quits after sprayer op -
erates
for 5 to 10 minutes.
1. Check Basic Electrical Problems on page 12. 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 manual 307–806.
.
CAUTION
Any short in any part of the
motor power circuit will cause
the control circuit to inhibit
sprayer operation. Correctly
diagnose and repair all shorts
before checking and replac-
ing
control board.
Building circuit breaker opens
as soon as sprayer is plugged
into outlet and sprayer is NOT
turned on.



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 ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 8.
For checking armature, motor winding and brush elec -
trical continuity .
Setup
Relieve pressure. Remove the drive housing. See
page 25.
Remove the motor shield (59), the fan cover (F) and
the inspection covers (J). See Fig. 10.
Remove the pressure control/cover (301). Disconnect
the – and + leads from the motor to the pressure con -
trol/cover terminals M–, and M+. See Fig. 1 1.
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
revolutions before coming to a complete stop. If the
motor does not spin freely , the armature is shorted and
the motor must be replaced. See page 27.
06995
Fig. 10
J
F
59
Armature, Brushes, and Motor Wiring Open
Circuit Test (Continuity)
Relieve pressure. Connect the two black motor leads
together 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
following: broken brush springs, brush leads, motor
leads; loose brush terminal screws, motor lead termi
-
nals; worn brushes. Repair parts as needed. See page
19.
If there is still uneven or no turning resistance, replace
the motor . See page 27.
04247
M–
M+
+–
Fig. 11
301

 
General Repair Information
To reduce the risk of a pressure control malfunc -
tion:
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
ELECTRIC SHOCK HAZARD
T o reduce the risk of serious injury ,
including 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.
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 12 – 16, to help
identify other possible problems and solutions.
CAUTION
Do not run the sprayer dry for more than 30 seconds
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
EXPLOSION 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. 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 ,
whenever you are instructed to relieve
pressure, follow the
Pressure Relief
Procedure on page 8.
NOTE: Read the GENERAL REP AIR INFORMATION
on
page 18 before doing this procedure.
1. Relieve pressure.
2. Remove the motor shield (59). Remove the in -
spection covers (J) and gaskets on each side of
the motor . See Fig. 12.
06995
J
59
Fig. 12
3.
Push in the spring clip to release its hooks from
the brush holder . Pull out the spring clip. See Fig.
13.
Fig. 13
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. 15.
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 carefully
to avoid damaging the parts.
6. Install a new brush so the lead is in the long slot of
the holder . See Fig. 14.
Fig. 14
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. 15.
Fig. 15
SPRING
BRUSH LEAD
TERMINAL SCREW
MOT OR LEAD
TERMINAL
BRUSH
SPRING CLIP
01227
8. Place the spring on the brush as shown in Fig. 14.
9. Install the spring clip and push it down to hook the
short slots in the housing. See Fig. 14.
10. Repeat for the other side.
11. Test the brushes.


Fig. 16
301
315
317
307
314
 
a.
Remove the pump connecting rod pin.
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
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 .
CAUTION
Do not run the sprayer dry for more than 30 seconds
while checking the brushes to avoid damaging the
displacement pump packings.
12. Install the brush inspection covers and gaskets.
13. Break in the brushes. Operate the sprayer for at
least one hour with no load. Install the connecting
rod pin.
Power Supply Cord Replacement (Fig. 16)
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 8.
NOTE: Read the GENERAL REP AIR INFORMATION
on
page 18 before doing this procedure.
1. Relieve pressure.
2. Remove the pressure control
board/cover (301).
3. Disconnect the power supply
cord (314), both blue and brown
leads from the ON/OFF switch (307),
and the green wire to the earthing or
grounding screw (317).
4. Loosen the strain relief bushing (315) and remove
the power supply cord (314).
5. Install the new power supply cord in the reverse
order.