Graco PRECISIONMIX 231-119 Operation manual

INSTRUCTIONS–P ARTS LIST 308–074
Rev A
This manual contains IMPORT ANT
WARNINGS AND INSTRUCTIONS
READ AND RETAIN FOR REFERENCE
PRECISIONMIX
PROPORTIONING CONTROLLER
FOR PROPORTIONAL MIXING OF PLURAL COMPONENT COA TINGS
Model 231–1
19, for Air Spray Systems
120 psi (8.4 bar) MAXIMUM FLUID WORKING PRESSURE
100 psi (7 bar) MAXIMUM AIR INPUT PRESSURE
FOR USE ONL Y IN ORDINAR Y LOCA TIONS.
DO NOT OPERA TE IN HAZARDOUS LOCA TIONS,
AS DEFINED IN ARTICLE 500 OF THE
NA TIONAL ELECTRICAL CODE (USA).
GRACO INC. P.O. BOX 1441 MINNEAPOLIS, MN 55440–1441
 COPYRIGHT 1991, GRACO INC.

Hazard of Using Fluids Containing Halogenated Hydrocarbons
Never
use 1,1,1–trichloroethane, methylene chloride, other halogenated hydrocarbon solvents or fluids containing
such solvents in this equipment. Such use could result in a serious chemical reaction, with the possibility of explosion,
which could cause death, serious bodily injury and/or substantial property damage.
Consult your fluid suppliers to ensure that the fluids used are compatible with aluminum and zinc parts.
WARNING
T ABLE OF CONTENTS
Safety Warnings 2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Definition of T erms 3. . . . . . . . . . . . . . . . . . . . . . . . . .
How the PrecisionMix W orks 3–5. . . . . . . . . . . . . . .
Typical Installation 6. . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 7, 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Controls and Indicators 9, 10 . . . . . . . . . .
Operation 11–13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service 15, 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostics Chart 17. . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Chart 18, 19 . . . . . . . . . . . . . . . . .
Air Schematic 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Schematic 21. . . . . . . . . . . . . . . . . . . . . . .
Parts Drawings and Lists
PrecisionMix 22, 23 . . . . . . . . . . . . . . . . . . . . . . .
Volume Counters 24. . . . . . . . . . . . . . . . . . . . . . .
Mixer Manifold 25. . . . . . . . . . . . . . . . . . . . . . . . .
Dispense V alves 26, 27 . . . . . . . . . . . . . . . . . . .
Flush V alves 28. . . . . . . . . . . . . . . . . . . . . . . . . . .
Static Mixer T ube Assembly 29. . . . . . . . . . . . .
Air Panel Assembly 30. . . . . . . . . . . . . . . . . . . . .
Pneumatic Package 31. . . . . . . . . . . . . . . . . . . .
Control Panel Assembly 32. . . . . . . . . . . . . . . . .
Accessories 33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensional Drawing 34. . . . . . . . . . . . . . . . . . . . . .
Technical Data 35. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warranty Back Cover. . . . . . . . . . . . . . . . . . . . . . . . .
Graco Phone Numbers Back Cover. . . . . . . . . . . . .


SAFETY W ARNINGS
SERIOUS BODILY INJURY, EXPLOSION, FIRE, OR ELECTRIC SHOCK
CAN OCCUR IF THE PRECAUTIONS BELOW ARE NOT FOLLOWED.
ELECTRICAL EQUIPMENT SHALL ONLY BE INSTALLED, OPERATED, AND SERVICED BY
TRAINED, QUALIFIED PERSONNEL WHO SHALL BE FULLY CONVERSANT WITH THE
REQUIREMENTS STATED WITHIN THIS INSTRUCTION MANUAL.
READ AND UNDERSTAND ALL INSTRUCTION MANUALS AND
WARNING LABELS BEFORE OPERATING THE EQUIPMENT.
FIRE, EXPLOSION, OR ELECTRIC SHOCK HAZARD
General Safety
To reduce the risk of fire, explosion, or electric shock:
1. DO NOT operate in hazardous locations, as defined in Article 500 of
the National Electrical Code (USA).
2. Operate the PrecisionMix in well–ventilated areas only .
3. The equipment MUST be grounded (see below).
4. Keep liquids away from the electrical components.
5. Disconnect electrical power at the main switch before servicing the
unit.
6. DO NOT disassemble the electrical control. Call a qualified electri -
cian.
Grounding
All parts of the fluid system must be properly grounded to reduce the risk
of static electricity discharge. Static electricity is created by the high ve -
locity
flow of fluid through the system. When the static electricity is dis -
charged,
sparking occurs. Sparks can ignite fumes from solvents and the
fluid being sprayed, dust particles and other flammable substances,
whether
you are spraying indoors or outdoors, and can cause a fire or ex -
plosion
and serious bodily injury and property damage.
In a low pressure air spray system, static sparking is generally not a prob -
lem.
However , some simple precautions should be taken to reduce the
risk. CHECK your local electrical code for detailed grounding instructions
for your area and type of equipment, and BE SURE to ground all of this
spray equipment:
1. PrecisionMix: the PrecisionMix electronics must be grounded
through an approved grounded power cord, connected to a
grounded
electrical socket. T o ground the PrecisionMix frame, use
a ground wire and clamp connected to a true earth ground. See
page
33 for an available ground wire and clamp.
2. Feed pumps or pressure pots: use a ground wire and clamp. See
your separate pump or pressure pot manual.
3. Air compressor: follow manufacturer ’ s recommendations.
4. Object being sprayed: according to your local code.
5. All solvent pails used when flushing, according to your local code.
Use only metal pails, which are conductive, placed on a grounded
surface. Do not place the pail on a nonconductive surface, such as
paper or cardboard, which interrupts the grounding continuity .
6.
T o maintain grounding continuity when flushing or relieving pres -
sure
, always hold a metal part of the spray gun firmly to the side of a
grounded metal pail, then trigger the gun.
Flushing Safety
Before flushing, be sure the entire system and flushing pails are properly
grounded. Refer to Grounding, at left. Follow the Pressure Relief
Procedure below
. Always use the lowest possible fluid pressure, and
maintain firm metal–to–metal contact between the gun and the pail during
flushing to reduce the risk of injury from fluid splashing or static sparking.
Pressure Relief Procedure
To reduce the risk of serious bodily injury , including splashing fluid
in the eyes or on the skin, always follow this procedure whenever
you shut of f the PrecisionMix, when checking or servicing any part
of the system, when installing, cleaning, or changing fluid tips, and
whenever you stop spraying.
1. Press the ST OP switch on the PrecisionMix control panel at
the beginning of the catalyst (component B) dispense.
2. Relieve fluid and air pressure at the component and solvent
feed pumps or pressure pots, as explained in their separate
instruction manuals.
3. Press the ST AR T switch on the PrecisionMix control panel.
4. Hold a metal part of the spray gun firmly to the side of a
grounded
metal pail, and trigger the gun to relieve fluid pres -
sure.
5. Set
the ON/OFF switch on the control panel to OFF , resetting
the machine control counters.
6. Set the ON/OFF switch to ON. Press the ST AR T switch.
7. Hold a metal part of the spray gun firmly to the side of a
grounded
metal pail, and trigger the gun to relieve fluid pres -
sure
in the component A fluid section.
If you suspect that the fluid tip or hose is completely clogged, or
that pressure has not been fully relieved after following the steps
above, VER Y SLOWL Y loosen the hose end coupling and relieve
pressure gradually , then loosen completely . Now clear the tip or
hose.
EQUIPMENT MISUSE HAZARD
General Safety
Any misuse of the spray equipment or accessories, such as
overpressurizing,
modifying parts, using incompatible chemicals and flu -
ids, or using worn or damaged parts, can cause them to rupture and result
in serious bodily injury , such as splashing fluid in the eyes or on the skin,
or fire, explosion or property damage.
NEVER alter or modify any part of this equipment; doing so could cause it
to malfunction.
CHECK all spray equipment regularly and repair or replace worn or dam -
aged
parts immediately .
Always
wear protective eyewear , gloves, clothing and respirator as rec -
ommended
by the fluid and solvent manufacturer .
System Pressure
NEVER exceed 100 psi (7 bar) air pressure to the PrecisionMix, and
NEVER
exceed 120 psi (8.4 bar) maximum fluid working pressure.
Be sure that all spray equipment and accessories are rated to withstand
the maximum air and fluid working pressures of the system. DO NOT ex -
ceed the maximum working pressure of any component or accessory
used
in the system.
Fluid Compatibility
BE SURE that all fluids and solvents used are chemically compatible with
the wetted parts of each of your system’ s components. Always read the
manufacturer’s literature before using fluid or solvent in your system.
IMPORTANT
United States Government safety standards have been adopted under the Occupational Safety and Health Act. These standards – particularly the Gen -
eral
Standards, Part 1910, and the Construction Standards, Part 1926 – should be consulted.

 3
DEFINITION OF TERMS
DANGER Alerts user to avoid or correct conditions
that
will cause death or serious bodily injury .
WARNING Alerts user to avoid or correct conditions
that
could cause bodily injury .
CAUTION Alerts user to avoid or correct conditions
that could cause damage to or destruction
of
equipment.
NOTE Identifies essential procedures or helpful in -
formation.
HOW THE PRECISIONMIX WORKS
The standard Graco PrecisionMix can blend all popular
two-component
epoxy or polyurethane paints. For infor -
mation on handling abrasive fluids, contact your Graco
representative or Graco T echnical Assistance (see back
page). The PrecisionMix is not for use with “quick-set-
ting”
paints (those with a pot life of less than 30 minutes).
The system can be set up to mix components supplied
from
pressure vessels, from feed pumps transferring the
materials from their original containers, or from a central
paint recirculating line.
The standard unit is designed to operate an air spray sys -
tem
with a capacity of up to 1000 cc/min with 80 psi (5.6
bar) fluid feed pressure. Higher flow rates are possible.
Operating Cycle
To begin operation, the spray gun operator turns ON the
ON/OFF switch, adjusts the SETPOINT selectors to de -
termine the appropriate volume ratio of the two compo-
nents to be mixed (according to the guidelines on pages
12 and 13), and presses the ST AR T button on the control
panel. From that point on, normal operation of the Preci -
sionMix
is controlled by the operation of the spray gun.
When the gun is triggered, the two components enter the
PrecisionMix through separate filters and check valves,
then are precisely monitored by two volume counters
(see Fig. 1). The measuring element of the volume
counters
consists of two precision gears and an electron -
ic sensor system. The sensors produce electrical im-
pulses
according to the gear tooth movement, signaling
two counts for each tooth. V olume counters are available
with the following volume displacement: 0.1, 0.4, and 1.6
cc/tooth.
The signals from the volume counters are compared to
the settings which were entered into the SETPOINT se -
lectors.
The actual ratio between the two components is
infinitely variable from 1:1 to 20:1 (depending on the vol -
ume
counters used). However , it is best not to exceed a
ratio of 10:1; for higher ratios, change the volume count -
ers
to obtain better tolerance control.
CONTROL
PANEL
DISPENSE
VALVE
A
(RESIN)
DISPENSE
VAL
VE B
(CATALYST)
VOLUME COUNTER A
MIXING
BLOCK
INTEGRATOR
STA
TIC MIXER
TUBE
VOLUME COUNTER B
AIR PURGE
VALVE
SOL VENT PURGE
VALVE
AIR CONTROL
ASSEMBLY
Fig. 1

4
When
the spray gun is triggered, the two components are
introduced into the integrator chamber one at a time (see
Fig. 2). Their entry into the chamber is controlled by a
dispense
valve for each component. The volume count -
ers monitor the exact quantities being dispensed, and
send electrical pulses to the controller. The controller
monitors
these pulses and turns the dispense valves on
or off accordingly (based on the preselected number of
counts
entered on the front panel).
The following is a typical ratio cycle:
First, the component A dispense valve opens, and
the fluid begins to flow into the integrator chamber.
When the correct quantity has been dispensed
(based on the volume counter input), the dispense
valve
closes.
Next, the component B dispense valve opens. The
fluid
begins to flow into the integrator chamber and is
lined up proportionately with the previously-dis-
pensed component A sample. When the correct
quantity
has been dispensed, the component B dis -
pense
valve closes.
The process repeats itself as long as the spray gun is
triggered. When the trigger is released, the unit
idles;
it will continue where it left of f when the gun is
triggered again.
If the spray gun is triggered, but the number of counts (of
a component) shown on the SETPOINT selector isn’t
reached
within a specified time, the system stops and an
alarm indicator lights. By the same token, if the number
of counts is exceeded by more than a tolerance which
has been set on a TOLERANCE selector, the system
also
stops, an indicator lights, and an overrun alarm is in -
dicated.
On leaving the mixing block, the components are pre-
mixed in an integrator and then given a homogeneous
blending
as they pass through a static mixer tube. Output
from the mixer tube to the spray gun is controlled by a
fluid
pressure regulator , if desired.
The two components continue to be alternately fed into
the mixing block as long as the gun is triggered. When
the trigger is released, the system idles. Operation can
also
be stopped at any time by pressing the ST OP button
or shutting OFF the ON/OFF switch on the control panel.
If the machine stops because of an excessive overrun,
the operator must press STOP to clear the program.
Pressing START will then restart the cycle at the same
count
where it stopped. If the problem still exists, the unit
will again shut down.
Adaptive Overrun Correction
The actual volume of fluid dispensed each cycle can vary
slightly from the settings on the SETPOINT selectors.
However, the system monitors this variance and com-
pensates
on the next cycle. For example, if the selector
for a component is set at 100, but 103 volume parts are
actually dispensed on the first cycle, then the system will
aim for 97 parts on the next cycle.
Whenever the fluid overrun is greater than the TOLER-
ANCE setting, an indicator on the control panel flashes
and
the system stops.
Manual Mode
When the MAN button on the control panel is pressed,
the system alternately dispenses three cycles of each
component and then stops. The manual mode is not
“adaptive”
– the T OLERANCE selectors are doubled, the
system does not monitor small variances from the SET -
POINT selections (but the “system monitors” explained
below are operative), and the alarm function does not
work.
External Controllers
The PrecisionMix is designed so that several of the con -
trol
panel functions can easily be duplicated using exter -
nal contactors. Refer to the electrical diagram on page
21 for information on connecting remote start and stop
controls,
or an external flushing control.
System Monitors
Time Control. T wo timers in the rear of the control box,
one for component A and one for B, monitor the run time
of the corresponding component’ s portion of the dispens -
ing cycle. The timer is activated from an air flow switch
contact
which monitors air flow to the spray gun indicat -
ing “gun on.” The timer resets at the end of the material
dispense
cycle. The timers can be adjusted between 00
and 99 seconds. The system shuts down and an indicator
lights if the “gun on” time exceeds the timer setting for
that
dispense.
To turn of f the time control monitoring, set the timer(s) at
“00”.
NOTE: Setting the timers to “00” will cause you to lose
the underrun feature (see Troubleshooting).
Volume
Control. The machine mixes best if the integra -
tor
fills with 30 - 50 cc of fluid (120 - 200 [T otal of A and B]
on the SETPOINT selectors). If the A and B selectors are
set so that their sum is greater than 200, the system
stops
and the overrun and underrun indicators flash alter -
nately.
Impulse Control. This control will detect a failure of a
flow
meter sensor and shut the system down.
Watchdog Control. The system also monitors all data
that
is controlled by its microprocessor , and shuts down if
anything (such as an electrical power surge) causes the
computer program to be interrupted.
System Flushing
The PrecisionMix can be manually flushed with a com-
patible
solvent and with air , as described in the Operation
section, or the flushing system can be tied to an automat -
ic control system. The ON/OFF switch must be OFF to
operate the pneumatic solvent and air flush buttons, un -
less
automated.

308074A 5
0584
0585
FUNCTIONAL DIAGRAM – COMPONENT A (RESIN) DISPENSE
COMPONENT A
INLET COMPONENT B
INLET
COMPONENT A
VALVE
AIR
PURGE SOLVENT PURGE
COMPONENT B
VALVE
FILTER
CHECK
VALVE
VOLUME
COUNTER
SHUT–OFF
VALVE
RA
TIO CHECK
VALVE
INTEGRATOR
STA
TIC MIXER
GUN SUPPL Y
FUNCTIONAL DIAGRAM – COMPONENT B (CA TALYST) DISPENSE
COMPONENT A
VALVE
AIR
PURGE SOLVENT PURGE
COMPONENT B
VALVE
COMPONENT A
INLET COMPONENT B
INLET
GUN SUPPL Y
FILTER
CHECK
VALVE
VOLUME
COUNTER
SHUT–OFF
VALVE
RA
TIO CHECK
VALVE
INTEGRATOR
STA
TIC MIXER
Fig. 2

6
AAir Supply Line
BBleed-T ype Air V alve
C
Air Line Filter
D Air Regulator & Gauge
E Supply T ank, Component A
F Supply T ank, Component B
G Supply Tank, Solvent
H Fluid Shutof f V alve
J
Air Solenoid V alves
K
Air Flow Switch
L Fluid Filter , Check V alve, and
fluid component inlet to
PrecisionMix
M
Air Flush V alve
N Solvent Flush V alve
P Fluid Hose
R Air Hose
S Main Power Switch
T1 15V 60 Hz Electrical Supply
U Fluid Pressure Regulator & Gauge
V Spray Gun
Y Ground Wire & Clamp (208-950
& 103-538)
Refer to the ACCESSORIES section
for further information.
IMPORTANT:
 Failure to limit air supply to 100
psi (7 bar) will void the Graco
warranty.
 Failure to ensure that the air
supply is dry and properly filtered
will void the Graco warranty .
HAZARDOUS
AREA NON–HAZARDOUS AREA HAZARDOUS AREA
*IMPORTANT: Electrical connections
must comply with all national, state,
and
local codes.
** Items are part of 948-559 Pressure Panel.
Fig. 3
TYPICAL INSTALLATION
A
BB**
C**
YJ
T*
S* S*
R
V
U
R
R
R
G
HHH
F
E
BD BDB D
LL
MN
K
D**
P

 7
INSTALLATION
NOTE: Reference numbers and letters in parentheses
in the text refer to the callouts in the figures and
the parts drawings.
See page 33 for accessories available from
Graco.
If you supply your own accessories, be
sure they are adequately sized and pressure-
rated
to meet the system’ s requirements.
WARNING
Installing and servicing this equipment requires ac -
cess to parts which may cause electric shock or
other serious bodily injury if the work is not per-
formed properly. DO NOT install or service this
equipment or perform any of the following installa -
tion and adjustment procedures unless you are
trained
and qualified.
WARNING
To prevent hazardous concentrations of toxic or
flammable vapors, spray only in a properly venti-
lated area. NEVER OPERATE THE SPRAY GUN
UNLESS
VENTILA TION F ANS ARE OPERA TING.
Check
and follow all national, state, and local codes
regarding air exhaust velocity requirements.
The T ypical Installation shown on page 6 is only a guide -
line for selecting and installing system components and
accessories,
and is not an actual system design. Contact
your Graco representative or Graco Technical Assis-
tance
(see back page) for assistance in designing a sys -
tem
to suit your particular needs.
The following instructions generally presume a standard
system using pressure tanks to supply the paint compo -
nents
and solvent, and air spray guns. See also “Option -
al System Arrangements” on page 8 for possible varia-
tions
and their ef fect on the instructions.
Unpacking
Unpack the shipping carton(s), and compare the con-
tents
to the packing list.
While unpacking, inspect the carton and the unit for any
signs of damage. Take note of any evidence of rough
handling
during shipment. Immediately report any dam -
age to the carrier’s claims agent, and also notify Graco
Customer
Service (T el. 708–671–8400).
If you find any damage, do not continue unpacking until
the PrecisionMix and shipping material have been in-
spected
by the claims agent.
Location
Set the PrecisionMix on a strong table or workbench with
a level top surface. The unit weighs approximately 260
lbs
(120 kg).
WARNING
The PrecisionMix is for use only in ordinary loca-
tions. DO NOT operate in hazardous locations, as
defined
in Article 500 of the National Electrical Code
(USA).
Assemble the PrecisionMix
Refer to Fig. 4. Install the power card into the control pan -
el,
in the slots provided.
SLOTS
TIGHTEN
TWO
SCREWS
T O SECURE.
INTERNAL
FUSE
Fig. 4
Refer to Fig. 5. Screw the baffle into the opening in the
front
of the mixing block, then screw in the integrator and
static mixer assembly .
BAFFLE
INTEGRATOR
STATIC
MIXER
Fig. 5
O–RING
Remove the keys for the control panel cover and the rear
control box, and store them in a safe place convenient to
the unit.

8
Install Paint and Solvent Supply Tanks
Refer to the T ypical Installation drawing on page 6. Note
also that separate installation instructions are provided
with
most accessories.
Install the supply tanks for the paint components (unless
you are connecting to a central paint recirculation sys-
tem)
and for the solvent.
Use solvent which is compatible with the paint being
mixed.
Connect the Fluid Supply Lines
Be sure all fluid hoses are properly sized for your system.
Use only grounded hoses.
Connect fluid hose between the paint supply and the fluid
filter inlets on the PrecisionMix. Connect base (color) to
the left filter inlet, and catalyst to the right filter inlet.
Connect fluid hose between the solvent supply tank and
the inlet on top of the solvent flush valve.
Install a 217-314 (air spray), or equivalent, Fluid Pres-
sure Regulator and Gauge on the PrecisionMix static
mixer
outlet, to control fluid pressure to the gun.
Connect fluid hose between the regulator outlet and the
inlet to the spray gun.
Connect the Air Supply Line
The PrecisionMix requires compressed air at 80 psi (6
bar). Connect the incoming air supply as shown in the
Typical Installation drawing.
To avoid contaminating your paint products, be sure the
air supply is free of oil and water . Be sure all air hoses are
properly sized for your system. Use only grounded air
hoses.
Refer
to the T ypical Installation drawing. Connect the air
supply to the air inlet of the paint and solvent supply tanks
(if pressure tanks are used). Include a regulator and
shut-off
valve in each line.
Connect air hose between the PrecisionMix air regulator
and the air inlet of the spray gun.
Pressurize the system with air , and check for leaks at all
connections. Relieve the air pressure after the test.
Fill the Fluid Supply Tanks
Fill the paint and solvent tanks. Refer to “Filling the Fluid
Tanks,” page 1 1.
Connect the Electrical Supply
WARNING
Electrical connections must comply with all applica -
ble
national, state, and local electrical codes.
Connect the PrecisionMix to a 120V AC 60 Hz grounded
supply (incoming power must be between 95 and 156
volts).
The unit draws less than 2 amps.
CAUTION
If power connections are not properly made, the
equipment
will be damaged.
Connect a 208-950 Ground Wire and 103-538 Clamp
from
the PrecisionMix frame to a true earth ground. See
page 33.
Graco recommends that the electrical service to this
equipment
be permanently installed in conduit.
Refer to the electrical schematic on page 21 for appropri -
ate connections for external contactors to control start-
ing,
stopping, or flushing.
NOTE: If you are using an external stop signal, you
must remove the jumper connecting terminals
25
and 27 on the rear of the control box.
Flush the Mixing System
The PrecisionMix was tested with lightweight oil at the
factory. Before operating for the first time, thoroughly
flush
the system with solvent to prevent contamination of
your fluids. See “Flushing the Mixing System,” page 1 1.
Adjust the Overrun
See “Adjusting the Overrun,” page 13.
Adjust the Metering Ratio
See “Checking or Adjusting the Metering Ratio,” page 12.
Adjust the Underrun Timer
The underrun timers are mounted on the circuit board on
the rear of the control box. They trigger the system to
shut
down if the preset count isn’t reached for the corre -
sponding component within the time set into that timer.
They can be set anywhere between “01” and “99”. Never
set
these timers to “00”, or the metering ratio could be in -
correct.
Start Production
See “Starting Production,” page 1 1.
OPTIONAL SYSTEM ARRANGEMENTS
OPTION “A” ––
Feeding Through Circulating Lines
If there is a central paint recirculating line in your shop,
the PrecisionMix can be connected to it instead of to
pressure supply tanks. Other than references to the
pressure tanks, operation is the same as described in
this manual.
The fluid supply must be free of pressure spikes (nor -
mally
caused by pump stroke changeover). If neces -
sary,
install pressure regulators on the fluid inlets to the
PrecisionMix, to reduce the feed pressure. Contact
Graco
for information on fluid pressure regulators.
For maintenance and safety, you must install a ball
valve between each supply line and the PrecisionMix
OPTION “B” ––
Feeding Through Pail or Drum Pumps
Instead of pressure supply tanks, the PrecisionMix can
be fed by pail or drum pumps. Operation is the same,
other than references to the pressure supply tanks.
The fluid supply must be free of pressure spikes (nor -
mally
caused by pump stroke changeover). If neces -
sary,
install pressure regulators on the fluid inlets to the
PrecisionMix, to reduce pulsation and pressure. Con -
tact
Graco for information on fluid pressure regulators.

 9
OPERATOR CONTROLS AND INDICA TORS
CONTROL P ANEL (Fig. 6)
ON/OFF Switch
This switch turns the PrecisionMix power on and of f.
Fuse Indicators
The three indicators light when the ON/OFF switch is
ON.
If an indicator is not lit, replace its associated fuse.
Electrical Test Points
For service use only .
Fuses
There
are separate fuses (shown) for each circuit in the
PrecisionMix, plus a 2-amp fuse on the inside of the pow -
er
card (see Fig 4).
Cycle Count Displays
These digital displays show the cycle count for compo-
nents
A and B as they are being metered through the vol -
ume counters. They are controlled by signals from the
volume counter sensors.
Refer to “SETPOINT Selectors” below. With all volume
counters,
the numbers on the cycle count displays repre -
sent
0.25 cc/count.
Display Indicators
An ON indicator (clear) lights while its corresponding dis -
pense
valve is open and allowing fluid flow from that vol -
ume
counter to the mixing block.
A B indicator (red) blinks when the system has counted
out an “underrun” of its component –– that is, when the
atomizing air flow is on and fluid hasn’t metered for the
time
set into the time control for that component.
A Y indicator (red) blinks when the system has counted
out an “overrun” of its component –– that is, when the ac -
tual
count is more than the T OLERANCE setting plus the
OVERFLOW setting.
A “ t ” indicator (clear) lights when the air is flowing to the
gun, and the timer is running.
START Button
This switch starts PrecisionMix operation.
An external contactor can be connected to terminals on
the rear of the control box to accomplish this function.
ST OP Button
This switch stops PrecisionMix operation, by deenergiz -
ing the component solenoids and thus closing the dis-
pense
valves. It also resets the electronics in preparation
for restarting. If the machine stops for any other reason,
you must press STOP to clear the program before re-
starting
(and it will restart at the same cycle count where it
left of f).
An external contactor can be connected to terminals on
the rear of the control box to accomplish this function.
MAN Button
This switch starts PrecisionMix operation for three dis-
pense
cycles of each component, and then stops the sys -
tem.
The alarms and the tolerance controls do not func -
tion
during this sequence. Y ou must press ST OP to clear
the program before pressing MAN.
An external contactor can be connected to terminals on
the rear of the control box to accomplish this function.
T OLERANCE Selectors (A and B)
These controls determine the overflow tolerance which
the system allows before shutting down if the preset
count (on the SETPOINT selectors) is exceeded.
SETPOINT Selectors (A and B)
These controls determine the volume of components A
and
B which will be run through the volume counters dur -
ing
each count cycle.
For ease of selecting the correct ratio of A and B compo -
nents,
the numbers on the SETPOINT selectors (and the
numbers on the cycle count displays) indicate cc’ s  4 .
FUSE
INDICATORS
ELECTRICAL
TEST
POINTS
FUSES
DISPLAY
INDICATORS
CYCLE COUNT
DISPLAYS
POWER CARD
Fig. 6
ON t ON t
ON
OFF
5V
24V
5V
1A
2A
1A START STOP MAN
TOLERANCE SET POINT TOLERANCE SET POINT
COMPONENT A COMPONENT B

10 
CONTROL BOX (Fig. 7)
Control Panel Cover Lock
This lock secures the control panel cover , to prevent tam -
pering
by unauthorized persons.
Air Pushbutton
This
button initiates air flush of the system (for as long as
it is pressed). When it is pressed, the air flush valve on
the back of the mixing block opens, allowing air to flow
from the compressed air supply through the left-hand
(base)
side of the mixing block and the outer tube of the
integrator. It operates only when the ON/OFF switch is
OFF.
Solvent Pushbutton
This button initiates solvent flush of the system (for as
long as it is pressed). When it is pressed, the solvent
flush
valve on the back of the mixing block opens, allow -
ing solvent to flow from the solvent supply tank through
the
right-hand side of the mixing block and the inner tube
of the integrator. It operates only when the ON/OFF
switch
is OFF.
MIXING ASSEMBLY (Fig. 7)
Dispense V alve Knobs
These knobs adjust the corresponding (A or B) dispense
valve opening, to limit the maximum fluid flow rate into the
mixing block.
Their setting is of minimal importance when the spray
gun
controls the process (except that they must be open
enough to allow adequate fluid flow).
Flush V alve Knobs
These knobs adjust the corresponding (air or solvent)
flush valve opening, to limit the flow rate into the mixing
block.
Fluid Shut-Off Knobs
These
knobs allow you to shut of f the outgoing fluid from
the volume counters to the integrator and spray device,
during
a ratio check.
Ratio Check V alve Knobs
These knobs allow you to measure the amount of A and B
component flowing to the mixing block, to check the vol -
ume ratio. They should not be opened unless the fluid
shut-off
knobs are closed.
Fluid Pressure Regulator (Optional)
This regulator controls the pressure of the mixed fluid
leaving
the PrecisionMix for the spray gun.
CONTROL BOX
CONTROL PANEL
COVER LOCK
AIR PUSHBUTT ON
DISPENSE
VALVE KNOBS
FLUID
SHUT-OFF
KNOBS
RA
TIO CHECK
VALVE KNOBS
SOLVENT
PUSHBUTTON
FLUSH
VALVE
KNOBS
Fig. 7

 11
OPERATION
The following instructions generally presume a standard
system using pressure supply tanks for the paint compo -
nents
and solvent, and air spray guns. See also “Option -
al System Arrangements” on page 8 for possible varia-
tions and their ef fect on the instructions.
Flushing the Mixing System
Flush the mixing system with solvent and air at the end of
each production day (or before any break which is longer
than the potlife of the fluid). Use the following flushing
procedure:
WARNING
For your safety , read the warning section Flushing
Safety on page 2 before flushing, and follow all the
recommendations given there. ALWAYS wear pro-
tective
eyewear when flushing.
1. T urn OFF the ON/OFF switch on the control panel.
2. Open the fluid pressure regulator .
3. During the following procedure (steps 4 – 7), follow
the instructions given in your separate gun manual
for
safely grounding your gun while flushing.
4. Pull the trigger to hold the spray gun open. If the gun
is air-operated, open it manually .
NOTE: Solvent
flushes the right-hand (catalyst) side of
the mixing block, and the inner tube of the inte -
grator. Air flushes the left-hand (base) side of
the
mixing block, and the outer tube of the inte -
grator. Depending on the components being
used,
you may want to flush with solvent, air , or
both – modify the following procedure accord-
ingly.
5. Press and hold the SOLVENT pushbutton (Fig. 7).
For
best results, use 60 to 100 psi (4.2–7 bar) of pres -
sure.
This
opens the solvent flush valve on the back side of
the mixing block, and solvent will flow from the supply
tank into the mixing system and to the gun.
6. As soon as solvent flows from the gun, stop pressing
the SOLVENT pushbutton. Press and hold the AIR
pushbutton
instead.
This actuates the air flush valve on the back side of
the mixing block, and air pressure will blow the sol-
vent
out of the system.
7. To thoroughly flush the system, alternately repeat
steps
5 and 6 with short bursts of solvent and air until
all solvent flowing from the spray gun is clear .
8. Adjust
the fluid pressure regulator back to the normal
working pressure.
Filling the Fluid Tanks
1. Make sure the supply tanks are not pressurized.
2. Remove the lids and fill the tanks with the appropriate
paint component or solvent, allowing at least 4 in.
(100
mm) head space below the lid.
CAUTION
Don’t allow dirt or foreign particles to enter the tank.
3. Close the tank lids.
4. Turn on the air supply and recharge the tanks with air .
Adjust
their air pressure to:
Components A & B – 30 to 70 psi (2 to 5 bar). Pres -
sure to the two tanks should be equal unless one
component
is more viscous (in which case the more
viscous component should have a higher pressure
setting).
Solvent
– 70 psi (5 bar).
Starting Production
NOTE: When you first start up the system after it has
been shut down (overnight, weekends, etc.), it
will cycle rapidly until system pressure is built
back
up. This is normal, and no cause for alarm.
1. Be sure the paint supply tanks are filled properly .
2. Be
sure the solvent tank is filled properly . Make cer -
tain the fluid valves are turned on and there is ade-
quate
fluid pressure supplied to the PrecisionMix. Be
sure the fluid shutoff knobs, dispense valve knobs,
and
flush valve knobs are all opened (see Fig. 7).
3. Determine the correct metering ratio, then check or
reset the SETPOINT and TOLERANCE selectors.
See “Checking or Adjusting the Metering Ratio”
(page
12) and “Adjusting the Overrun” (page 13).
4. If necessary, adjust the underrun timers on the rear
of
the control box.
5. Turn ON the ON/OFF switch on the control panel.
The
top three fuse indicators and the digital displays
will light. Make certain all voltage indicator lights are
lit (see Fig. 6).
6. Remove any air from the fluid lines of the system:
a. Shut of f the air to the gun by closing the air regula -
tor
on the PrecisionMix.
b. Hold a metal part of the spray gun firmly to the
side
of a grounded metal pail and pull the trigger .
c. Press
the ST AR T button.
d. If the volume counters overrun because of air in
the system, operation will stop. Just repeatedly
press STOP and then START again until paint
flows
air-free from the spray gun.
7. If the paint output is too low , increase the air pressure
on both supply tanks; if too high, reduce the air pres -
sure,
close the dispense valves further , or adjust the
fluid pressure regulator .
CAUTION
Do not use the first 4 to 5 oz of paint from the sys-
tem,
as it may not be thoroughly mixed.
8. Check the air pressure regulators on the supply
tanks,
to be sure that the feed pressures are approxi -
mately
the same.
9. Check or reset the air regulator in the spray air line.
10. Check or reset the (optional) fluid pressure regulator
on the static mixer outlet. Use the adjustment key to
adjust the regulator .
11. Begin production by pressing START, or (if so
equipped)
with an external start signal.

12 
During Production
CAUTION
Never allow the paint supply tanks to empty com-
pletely while the unit is operating. Top them from
time
to time as needed. Failure to do so may cause
the metering ratios to be incorrect.
Operation of the PrecisionMix is controlled by the opera -
tion
of the spray gun. When the gun is triggered, the dis -
pense
valves open and allow the A and B components to
enter the mix manifold and be mixed and dispensed to
the
gun.
If required, switch on the supply tank agitators briefly
whenever
the fluid needs stirring.
Periodically check the fluid level in the paint and solvent
supply tanks, and refill as necessary .
Stopping Production
Stop machine operation at any time by pressing ST OP, or
(if so equipped) with an external stop signal.
If your stop time or break time is shorter than the potlife of
the components, no additional action is needed (other
than
to relieve pressure at the spray gun).
However, before or after breaks which exceed the potlife,
you must flush the mixing system (see “Flushing the Mix -
ing
System,” page 1 1).
Color Change
Follow this procedure:
Before using the PrecisionMix system for the first
time
Before
changing the color of the paint.
1. T urn OFF the ON/OFF switch.
2. Bleed of f all fluid pressure on both dispense valves.
3. Disconnect the base supply and catalyst supply , and
connect a regulated solvent line in both places.
4. T urn ON the ON/OFF switch and press ST ART.
5. At the spray gun, purge the fluid into a grounded
waste
container until the solvent comes out clear .
6. T
urn OFF the ON/OFF switch.
7. Bleed off all fluid pressure on the solvent. Discon-
nect
the solvent supply from the filter inlets, and con -
nect the new color in its place, then reconnect the
catalyst
supply line.
8. Reset the SETPOINT selectors to the appropriate
new
setting.
9. T urn ON the ON/OFF switch, and press ST ART.
10. Dispense
the paint into a grounded waste container
until it is spraying the new color .
11.
Begin production.
NOTE: For other color change options, contact your
Graco
representative.
Checking or Adjusting the Metering Ratio
NOTE: This procedure gives typical examples for Mod -
el
231–1 19; other configurations may be some -
what
dif ferent.
To adjust the SETPOINT selectors, and to verify that the
PrecisionMix is actually outputting the volumes entered
into
the selectors, follow this procedure:
NOTE: To set the metering ratio between the compo-
nents
to be mixed (A and B), you must know the
desired ratio by volume, as you will be adjusting
the ratio in volume parts. If this information is
not
all available, ask your material supplier .
1. IMPORTANT: Turn the fluid shut-off knobs all the
way
into the block.
2. Be sure that there is enough paint in the supply
tanks,
and that the tanks are charged with air .
3. Turn ON the ON/OFF switch. The two digital cycle
count
displays will come on.
4. Adjust the SETPOINT selectors to the proper mix ra -
tio
of components A (resin) and B (catalyst).
NOTE: The integrator holds 60 cc of fluid. T o avoid
overfilling, it is best to fill it only about
3/4
full
each cycle – 40 to 50 cc of the mixture of
components
A and B.
Each count on the displays represents 0.25 cc of ma -
terial
passing through the volume counter . The total
number of counts required for a 50-cc fill is therefore
50  0.25, or 200.
This total (200 counts) must be appropriately divided
between components A and B according to the spe -
cified mix ratio, and in such a way that the total
counts
per cycle doesn’t exceed 200.
To understand how to set the selectors to get that mix
ratio, it is easier to follow through an example.
EXAMPLE 1:
a. Assume that you want a mix ratio of 3:1 (3 ratio
units
of A and 1 ratio unit of B, or a total of 4 ratio
units). Divide the total counts (200) by the total
ratio
units (4) – at a 3:1 ratio, each ratio unit repre -
sents
50 counts.
b. Determine the volume of each component need -
ed
to get the desired ratio:
Component A:
3 ratio units x 50 counts = 150 counts
Component B:
1 ratio unit x 50 counts = 50 counts.
EXAMPLE 2:
a. Assume this time a mix ratio of 9:1, a total of 10
ratio units. Divide the total counts (always 200)
by
the total ratio units (this time 10) – at a 9:1 ratio,
each ratio unit represents 20 counts.
b. Determine the volume of each component need -
ed
to get the desired ratio:
Component A:
9 ratio units x 20 counts = 180 counts
Component B:
1 ratio units x 20 counts = 20 counts.
The following table provides starting SETPOINT se -
lector
settings for a number of common ratio mixes.
These settings don’t always add up to 200 counts,
because
they have been adjusted for slightly greater
precision than the above procedure provides.

 13
Starting
SETPOINT Selector Settings[*]
RATIO COMP. A COMP. B
1 : 1 100 100
1.5: 1 120 80
2 : 1 128 64
2.5: 1 140 56
3 : 1 148.8 49.6
3.5: 1 151.2 43.2
4 : 1 160 40
4.5: 1 158.4 35.2
5 : 1 160 32
5.5: 1 167.2 30.4
6 : 1 168 28
6.5: 1 166.4 25.6
7 : 1 173.6 24.8
7.5: 1 168 22.4
8 : 1 172.8 21.6
8.5: 1 163.2 19.2
9 : 1 180 20
9.5: 1 167.2 17.6
10 : 1 176 17.6
10.5: 1 168 16
[*] T otal of A + B cannot exceed 200.
NOTE: The settings must always be fine-tuned af -
ter
you measure the actual flow with a ratio
check using real paint (steps 5–9 below).
5. Set the TOLERANCE selectors (see “Adjusting the
Overrun,” at right).
6. Check the ratio as follows:
WARNING
To reduce the risk of fluid splashing in the eyes or on
the skin, AL WA YS wear protective clothing, eyewear ,
and
gloves when checking the ratio.
a. Press ST OP.
b. Place
a large paint- and solvent-resistant cup un -
der
the ratio check fluid hoses.
c. Turn the two fluid shutoff valves all the way in
(clockwise).
d. Open
the two ratio check valves.
e. Press ST ART , and allow the machine to run until
all air is pushed out of the ratio check hoses.
Then close the catalyst ratio check valve while
the
machine is dispensing resin material. This will
cause the machine to stop at the end of the resin
cycle.
f. Place
a clean cup under each ratio check hose.
g. Open the catalyst ratio check valve, so the ma-
chine will cycle. When you have an appropriate
sample size, close the catalyst valve while the
machine
is dispensing resin (as in step “e”).
h. W eigh the samples, to evaluate.
7. If the measured ratio is not exactly correct, readjust
the SETPOINT selectors. Repeat the ratio check
(step
6) until it is within the specification range of your
paint components.
8. Flush the ratio check valves as follows:
a. T urn OFF the ON/OFF switch.
b. Place a fluid cup under the ratio check valves.
c. Press the yellow SOLVENT pushbutton until
clear solvent flows through the catalyst ratio
check
valve hose.
d. Close the catalyst ratio check valve.
e. Open the fluid shutof f valves.
f. Press the yellow SOL VENT pushbutton until sol -
vent pushes all of the resin out of the ratio check
valve hose.
g. Close the resin ratio check valve.
CAUTION
Don’t use the first system fill of mixed material for
production,
as the ratio may be incorrect.
Adjusting the Overrun
To the left of each SETPOINT selector is an additional se -
lector
for adjusting the overflow tolerance. Under normal
conditions, these latter units should be programmed to
read “1” or “2.”
Depending
on component viscosity and output, a volume
counter may overrun the SETPOINT setting by one or
two digits. If it does, the TOLERANCE selector would
stop production if it had been set at “0” (no tolerance).
However, setting OVERFLOW to a number higher than
zero
allows the SETPOINT selector to overrun up to that
specified limit without the nuisance of unnecessary shut-
offs.
Overrun
can also be limited by restricting the opening of
the dispense valves. To do so, turn the valve knobs
clockwise
until they are screwed all the way in, then turn
back 1/4 to 1/2 turn. If this limits the fluid flow too much,
open the valve knobs slowly step-by-step until you get
the
required output.
Adjusting the Atomizing Air Regulator
There are two regulators on the left side of the frame, for
adjusting the pressure of the atomizing air. Depending
on
the spray finish you desire you may have to adjust the
air pressure with this regulator .
Adjusting the TIME LIMIT Timers
In line with the spray air regulator (in back of the control
box) there is a switch which senses air flow to the spray
gun. If fluid is flowing to the gun, the two dispense valves
cycle on and off as the A and B components are alter-
nately fed to the mixing block. However, if spray air is
flowing (as sensed by the air flow switch), but the dis-
pense
valve doesn’t cycle within the time set into the tim -
ers,
operation stops and the associated “  ” indicator on
the control panel lights. (Refer to “T ime Control” on page
4.)
To resume operation, you must press STOP and then
START
again.
Adjusting the Fluid Pressure Regulator
(Optional)
1. Using the adjustment key, turn the regulator knob
counterclockwise
until spring tension is released (no
fluid pressure on the regulator).
2. T urn ON the ON/OFF switch.
3. Open the spray gun.
4. Turn the key clockwise until the gauge shows the re -
quired
pressure.

14 
MAINTENANCE
Daily Maintenance
Flush the mixing system (see page 1 1) at the end of
your production.
 Clean the spray gun.
Check the fluid level in both paint supply tanks, and
refill as necessary .

Check the fluid level in the solvent supply tank, and
refill as necessary .
Weekly Maintenance
Disconnect the integrator and spray mixing tube as -
sembly. Clean and inspect it, and ensure that the
small
distributor holes in the baffle are all open.
Be sure the packing retainers are snug on the dis-
pense
valves and the air and solvent flush valves.
Disassemble the fluid filters at the inlet of the volume
counters. Clean and inspect the filter elements (the
elements can be replaced when dirty, or can be
cleaned and re-used).
Adjust packing nuts on dispense valves and flush
valves.
Shut off the air supply and depressurize the filter.
Wash
all parts of the filter (including the element) with
household soap and water, and blow out the filter
body. Replace the element when there is a visible
coating of dirt or condensate on the surface (or if
there
has been excessive pressure drop).
Preventive Maintenance
At least once a year, take apart the mix manifold
(mixing
block, dispense valves, flush valves, and ra -
tio check valves). Clean and inspect them, and re-
place
all o-rings and v-packings (repair kits are avail -
able from Graco).
Once a year, disassemble and clean the volume
counters.

 15
SERVICE
Tools Needed for Disassembly
Set of open-end wrenches
 Set of metric hex key wrenches
V arious retaining ring pliers
 Flat-blade screwdrivers.
Disassembling the Dispense Valves
WARNING
To reduce the risk of electric shock, splashing fluid in
the eyes or on the skin, or other serious injury, AL-
WAYS follow the Pressure Relief Procedure on
page 2 and disconnect all power to the PrecisionMix
before servicing.
To remove the complete valve assembly from the
mixing block:
Refer to Fig. 8.
1. Disconnect the incoming fluid line from the volume
counter.
2. Disconnect
the two air line connections.
3. Loosen the two cap screws (A) until the valve is free
from the mixing block.
4. Carefully lift off the valve assembly. The valve seat
and bottom o-ring may fall away .
CAP SCREW
(A)
ADJUSTING
SCREW
AIR LINE
CONNECTORS
CONNECTING
ROD
PACKING
NUT
Fig. 8: Dispense Valve
CAP
NUT
FLUID
SECTION
AIR
SECTION
CAP SCREW
(B)
To remove just the top (air) section of the valve:
Refer to Fig. 8.
1. Disconnect the two air line connectors.
2. Unscrew the adjusting screw far enough for the valve
cap screws (B) to clear it.
3. Remove the two cap screws (B) that go into the con -
necting
rods. DO NOT remove the two screws that
are secured by cap nuts.
4. With a hex wrench or similar tool, unscrew the pack -
ing
nut.
5. Pull of f the top section of the valve. This is a snug fit.
To disassemble the top (air) section of the valve:
WARNING
Wear protective eyewear and exercise caution
when
disassembling a dispense valve.The air sec -
tion of the valve is spring-loaded, and parts may fly
out or spring apart when the valve is disassembled.
Refer to Fig. 8 and the parts drawing on page 27.
NOTE: Spare Parts Kit 948–591 is available to repair
the dispense valves. Order one kit for each
valve.
See the parts list on page 26.
1. Remove the top section of the valve (see above).
2. Unscrew the adjusting screw .
3. Remove the two screws that are secured by cap
nuts.
Be careful – the cylinder halves are under ten -
sion and will spring apart. Also, the detent pin will
spring
out from the cylinder cap.
4. Remove the top retaining ring from the piston rod (in -
side
the cylinder).
5. Pull the piston rod down and hook under the top pis -
ton
with a hex wrench or similar tool.
6. Remove the remaining retaining rings to complete
disassembly
of the cylinders.
7. Inspect the o–rings on the piston and piston rod.
Clean all parts and replace as necessary. Reas-
semble
in reverse order .
When reassembling, be sure the two air connection
ports
will be facing the outside of the machine.
To disassemble the bottom (fluid) section of the
valve:
Refer to Fig. 8 and the parts drawing on page 27.
1. Remove the top section of the valve (see above).
2. Remove the glands and v–packings from the fluid
housing.
3. Clean and inspect all parts, and replace as neces-
sary.
Reassemble in reverse order .

16 
Disassembling the Flush Valves
WARNING
To reduce the risk of electric shock, splashing fluid in
the eyes or on the skin, or other serious injury, AL-
WAYS follow the Pressure Relief Procedure on
page 2 and disconnect all power to the PrecisionMix
before servicing.
To remove the complete valve from the mixing block
and mounting plate:
1. Disconnect the air line connections.
2. Remove the screw (C).
3. Remove the two screws (D).
T o disassemble the valve:
WARNING
Wear protective eyewear and exercise caution
when disassembling a flush valve.The air section
of
the valve is spring-loaded, and parts may spring
apart when the valve is disassembled.
NOTE: Spare Parts Kit 948–592 is available to repair
the flush valves. Order one kit for each valve.
See
the parts list on page 28.
Refer to Fig. 9 and the parts drawing on page 28.
1. Hold the piston rod with a hex wrench or similar tool,
and unscrew the coupling.
2. Remove the four cap nuts. Be careful – the air sec -
tion
is under tension and will spring apart.
3. Inspect the o–rings on the piston and piston rod.
4. Remove the packing from the fluid housing.
5. Clean and inspect all parts, and replace as neces-
sary.
Reassemble in reverse order .
When reassembling, be sure the two air connection
openings
are on the side of the valve, facing the outside
of
the machine.
SCREWS (D)
SCREW (C)
AIR LINE
CONNECTORS
Fig. 9: Flush V alve
AIR
SECTION
FLUID
SECTION
COUPLING
PISTON
ROD
Disassembling the Volume Counters
WARNING
To reduce the risk of electric shock, splashing fluid in
the eyes or on the skin, or other serious injury, AL-
WAYS follow the Pressure Relief Procedure on
page 2 and disconnect all power to the PrecisionMix
before servicing.
T o remove a volume counter from its adaptor plate:
1. Disconnect the electrical connector from the bottom
of the counter .
2. Remove
the four screws (E) to separate the volume
counter from the adaptor plate. Don’t lose the two o-
rings.
To disassemble the volume counter:
CAUTION
This is a close-tolerance device. It will be damaged
if forced apart during disassembly .
1. Loosen
the four screws (F). Leave about two threads
connected.
2. The two halves of the counter are pinned together
(the
pins are part of the sensor plate assembly) and
will be difficult to separate. See Fig. 10.
Hold the housing and tap the screws one at a time in
a consistent sequence, and eventually the two
halves will come apart. Don’t lose the thin shim on
each
side of each gear .
When reassembling, note that one edge of the gear
teeth
is chamfered. See Fig. 10.
T orque the screws to 7.5 ft-lbs (10 N.m).
CAUTION
Never immerse a volume counter in solvent for
cleaning.
Doing so will damage the electronics.
SCREWS
(F)
(QTY 4)
HOUSING
O-RING
SHIMS (QTY 4)
SCREWS
(E) (QTY 4)
METERING
GEARS (2)
ELECTRONIC
MODULE
CHAMFERED EDGE
ON GEAR TEETH
Fig. 10: V olume Counter

 17
DIAGNOSTICS CHART
Installing and servicing this equipment requires access to parts which may cause electric shock or
other serious bodily injury if the work is not performed properly. Do not install or service this equip-
ment unless you are trained and qualified. Always disconnect power to the PrecisionMix before
cleaning or servicing.
To
reduce the risk of serious bodily injury , including splashing fluid or solvent in the eyes or on the skin,
always follow the Pressure Relief Procedure on page 2 when checking, adjusting, cleaning, or re -
pairing any part of the system.
WARNING
PROBLEM INDICATION FAULT CAUSE
Overdose
Fault Alternating red LEDs. V olume of resin + Setpoint of resin +
BY volume of catalyst is setpoint of catalyst is
> 50 cc. > 200 counts.
Leakage Fault/ Flashing red LEDs. V olume measured is Fluid valve did not close
Simultaneous Flow Y > 2 x tolerance value fully.
while system is in
START mode. Fluid leakage between
the volume counter and
the valve seat.
Solenoid failed to shift.
Improper tolerance
setting.
Excessive pressure
pulses from feed supply .
Sensor Fault Alternating red LEDs. Electrical failure of one Improper assembly .
BY
volume counter sensor .
Faulty component.
Wire failure.
Underrun Fault Flashing red LED. Measured volume is Plugged fluid line.
B < set volume for a
fixed time period. Air usage or leakage
The timer is triggered without fluid flow .
by sensing atomizing
air flow to the spray Improper timer setting.
gun. NOTE:
A timer setting of
00 sec will delete the
timer.
Overrun Fault Flashing red LED. Measured volume is Fluid valve did not close
Y > set volume + fully.
tolerance.
Fluid leakage between
the volume counter and
the valve seat.
Excessive flow rate;
fluid valve cannot close
fast enough.
Solenoid failed to shift.

18 
TROUBLESHOOTING CHART
PROBLEM CAUSE SOLUTION
System
won’t run. No power .T urn ON/OFF switch ON.
Be sure main electrical disconnect
switch is closed.
Check fuses.
System aborted, and:
Overrun indicator Y flashing on Push ST OP , then ST ART. If prob-
either channel. lem reoccurs: set tolerance one digit
higher; or , check for valve or tube
leakage, and repair .
Underrun indicator B flashing on Push ST OP , then ST ART. If prob-
either channel. lem reoccurs: adjust underrun timer
to a larger number; or , check for air
leaks in lines between air flow switch
and gun, and repair .
Overrun and underrun indicators 1. Check volume counter cable for
Y and Bflashing alternately on that channel. Replace if defec-
either channel. tive.
2.
Check ratio setting. If over 200
(See also “System shuts itself down total (A + B), reset.
when running,” below .) 3.
Check for valve seat leakage.
4. Check for fluid leak between vol-
ume counter and valve.
5. Replace volume counter .
System cycles rapidly System pressure not built up yet. Normal.
when first started after
shutdown.
System shuts itself down Paint supply tank(s) empty . Refill supply tank(s). Bleed air from
when running. lines.
No air pressure (or low pressure) Increase air pressure, or check the
in fluid supply tanks. valves and regulators in supply lines.
Fluid pressure regulator shut of f Adjust regulator .
(or set too low).
Check valve clogged. Remove and clean.
Fluid filter element dirty . Remove and clean.
V olume counter dirty . Remove and clean.
Cable disconnected or broken Reconnect, or replace cable.
between volume counter and
electrical compartment (cycle
count display will show “0000”).
TIME LIMIT timer(s) set for too Change setting.
short a time. Flashing red LED B.
Clogged spray gun. Unclog. T o restart, press ST OP,
then ST ART.

 19
TROUBLESHOOTING CHART (CONT .)
PROBLEM CAUSE SOLUTION
No
material flow (or Dispense valves closed too far . Open valve knobs further (counter-
not enough). clockwise).
Fluid shut-of f valves closed too far .T urn shut-of f knobs all the way coun-
terclockwise.
V
olume counter overrun. Reduce the fluid flow by turning
Flashing red LED Y. the dispense valve knobs clockwise
1/4 or 1/2 turn.
Reduce air pressure on fluid supply
tank, to reduce material flow .
Refill fluid tank (air passing through
the volume counter will cause
overrun).
V
olume counter underrun. Clean the fluid filter and inspect
Flashing red LED B. for blockage.
Increase air pressure on fluid supply
tank, to increase fluid flow .
T
urn the dispense valve knobs
counterclockwise 1/4 to 1/2 turn.
Check mixer system to be sure lines
are clear . Flush the system and
check the integrator .
Check that all spray gun openings
are free.
Be sure the TIME LIMIT timer is
adjusted properly .
Fluid not properly mixed. System was just turned on. Normal: do not use the first 4 to 5
oz. of paint after startup.
Solvent flush won’t ON/OFF switch is turned ON. T urn switch OFF .
operate.
Low solvent supply or pressure. Be sure the solvent tank is full of sol-
vent and charged with air .
Blockage in system. Check the solvent flush valve knob:
if turned all the way in, the valve
won’t open and no solvent can flow
through.
Check the spray gun for blockage.
Pot life exceeded. Be sure the potlife of the fluid hasn’t
been exceeded.
Fluid leaks from weep Loose packing inside fluid housing. T ighten packing nut. Refer to parts
hole on side of dispense list drawing: ref. no. 20 on dispense
or flush valve. valve; ref. no. 7 on flush valve.

20 
AIR SCHEMATIC
Remote Flush Control
Part No. 948–596
Air Flush
Valve
Solvent
Flush
Valve
Filter
Air
Supply
Dispense V alve B
Dispense V alve A
Air Shuttle V alve Solvent Shuttle V alve
ON
OFF
ON
OFF
ON
OFF
ON
OFF
Spray Gun No.2Spray Gun No.1
Gauge
Regulator
Component A
Component B
ON/OFF
Valve
Air
Pushbutton
Solvent
Pushbutton
Purge
Interlock
Air
Flow
Switch
1
2
3
42
45
3
1
2
3
42
45
3