®

950/1025/1050/1055
950 ProRacer
Computer Wheel Balancers

Service Manual and

Troubleshooting Guide

P.O. Box 3002, 1601 J. P. Hennessy Drive, LaVergne, TN USA 37086 615/641-7533 800/688-6359 Manual Part: 9111123 03
HENNESSY INDUSTRIES INC. Manufacturer of AMMCO®, COATS® and BADA® Automotive Service Equipment and Tools. Revision: 11/05
 Direct Drive

ii • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Safety Notes . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Contactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Auxiliary Contactor Block . . . . . . . . . . . . . . . . . . . . .22
Equipment Needed . . . . . . . . . . . . . . . . . . . . . .1 Bridge Rectifiers . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Voltage & Phase Checking Procedure . . . . . . .2 A & D Arm Assembly . . . . . . . . . . . . . . . . . . . . . . .23
Fan Motor Assembly . . . . . . . . . . . . . . . . . . . . . . . .23
Preliminary Inspection . . . . . . . . . . . . . . . . . . .3
Rotary Shutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Functional Checks
Optical Encoder Assembly . . . . . . . . . . . . . . . . . . . .23
Operational Check . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Drive Motor Assembly . . . . . . . . . . . . . . . . . . . . . . .24
Accuracy Check (Plane Separation) . . . . . . . . . . . .3 - 4
Piezo Assembly . . . . . . . . . . . . . . . . . . . . . . . .24 - 25
Rotational Check (Use a Hub Centric Wheel) . . . . . . .4
Capacitor Assembly . . . . . . . . . . . . . . . . . . . . . . . . .25
Calibration Procedures
Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Weight Sensor Calibration . . . . . . . . . . . . . . . . . . . . .4
Signal Harness . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
A & D Arm Calibration (Code 10) . . . . . . . . . . . . . .4 - 5
Repair Procedures for the A & D Arm Assembly
Stop-On-Top Calibration (Code 20/21) . . . . . . . . . . . .5
A Pulley Removal . . . . . . . . . . . . . . . . . . . . . . . . . .26
*Distance Gauge Tape Placement (Optimize A) . . . . .5
A Pulley Installation/Adjustment (Code 10) . . . . . . . .26
Error Codes . . . . . . . . . . . . . . . . . . . . . . . . .5 - 6
A Potentiometer Replacement . . . . . . . . . . . . . . . . .26
*Function Codes . . . . . . . . . . . . . . . . . . . . . .6 - 7 D Pulley Removal . . . . . . . . . . . . . . . . . . . . . . . . . .26
Troubleshooting Section for Models 950, 1025, D Pulley Installation/Adjustment (Code 10) . . . . . . . .27
1050, & 1055 Balancers . . . . . . . . . . . . . . .7 - 16 D Potentiometer Replacement . . . . . . . . . . . . . . . . .27
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
*Motor Service Kit Instructions . . . . . . . . . . .28
Fan Motor Does Not Run (Contactor Model) . . . . . . .8
*950 Pro Racer . . . . . . . . . . . . . . . . . . . . . . . . .28
Accuracy Problems (Plane Separation) . . . . . . . . . . . .8
*950 Pro Racer Wiring Diagram . . . . . . . . . . . . . . . .29
Rotational Problems (Contractor & Motor
Controller Model) . . . . . . . . . . . . . . . . . . . . . . . . . . .9 *950 Wiring Diagram (Contactor Style) . . . . .30
Repeatability Problems (Contractor & Motor *1050 Wiring Diagram (Contactor Style) . . . .31
Controller Model) . . . . . . . . . . . . . . . . . . . . . . . . . . .10 *Solid State Wiring Diagrams &
Display Does Not Light (Contactro Model) . . . . . . . .11 Troubleshooting Guides . . . . . . . . . . . . . . . . .32
Balancer Does Not Cycle (Contactor Model) . . .12 - 13 For units produced after 1/1/98 . . . . . . . . . . . . . . . .32
Balancer Does Not Brake (Contactor Model) . . .14 - 15 Mechanical Hood Switches . . . . . . . . . . . . . . . . . . .32
A & D Arm Problems . . . . . . . . . . . . . . . . . . . . . . . .16 Mechanical Hood Switch Diagram . . . . . . . . . . . . . .33
Checking Procedures *1050 Wiring Diagram (Motor Controller
*Bridge Rectifiers . . . . . . . . . . . . . . . . . . . . . . . . . .17 Style/Magnetic Switches) . . . . . . . . . . . . . . . . . . . .34
*Optical Encoder (Code 44) . . . . . . . . . . . . . . . . . . .17 *1050 Wiring Diagram (Motor Controller
Style/Mechanical Switches) . . . . . . . . . . . . . . . . . . .36
*Motor Circuit Testing . . . . . . . . . . . . . . . . . . . . . . .17
*Motor Controller Test Box #8112708 . . . . . . . . . . .38
*Motor Circuit Diagram . . . . . . . . . . . . . . . . . . . . . .18
*Display Does Not Light (Solid State Motor
*Piezo Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Controller Model) . . . . . . . . . . . . . . . . . . . . . . . . . .39
Replacement Procedures Section for Models *Balancer Does Not Cycle (Solid State Motor
950, 1025, 1050, & 1055 Balancers . . . . . .20 - 25 Controller Model) . . . . . . . . . . . . . . . . . . . . . . . . . .40
Front Panel/Printed Circuit Board Assembly . . . . . . .20 *Balancer Does Not Brake (Solid State Motor
Contactor Coil Resistance Measurement . . . . . . . . .20 Controller Model) . . . . . . . . . . . . . . . . . . . . . . . . . .41
Front Panel/Printed Circuit Board Assembly *PCB Checklist Addendum . . . . . . . . . . . . . . .42
Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 Diode Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Touch Panel/Aluminum Back Panel and PCB Assembly . . . .20 IC Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Hood Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
*Glossary of Terms . . . . . . . . . . . . . . . . . . . . .43
Magnetic Hood Switch . . . . . . . . . . . . . . . . . . . . . .21
*This manual has been updated to include all related
*Mechanical Hood/Interlock Switch . . . . . . . . . . . . .21 models. Items that are new are high lighted by an asterick
On/Off Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 (*) for your convenience.
Circuit Breakers . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • iii

 Safety
IMPORTANT SAFETY INSTRUCTIONS
READ ALL INSTRUCTIONS
1. Eye and face protection recommendations: 10. Wear proper clothing. Safety toe, non-slip
footwear and protective hair covering to contain
“Protective eye and face equipment is required to
hair is recommended. Do not wear jewelry, loose
be used where there is a reasonable probability of
clothing, neckties, or gloves when operating the
injury that can be prevented by the use of such
balancer.
equipment.” O.S.H.A. 1910.133(a) Protective gog-
gles, safety glasses, or a face shield must be pro- 11. Keep work area clean and well lighted. Cluttered
vided by the owner and worn by the operator of and/or dark areas invite accidents.
the equipment. Care should be taken to see that
12. Avoid dangerous environments. Do not use power
all eye and face safety precautions are followed by
tools or electrical equipment in damp or wet loca-
the operator. ALWAYS WEAR SAFETY GLASSES.
tions, or expose them to rain.
Everyday glasses only have impact resistant
lenses, they are not safety glasses. 13. Avoid unintentional starting. Be sure the balancer
is turned off before servicing.
2. Do not disable hood safety interlock system, or in
any way shortcut safety controls and operations. 14. Disconnect the balancer before servicing.
3. Be sure that wheels are mounted properly, the 15. Use only manufacturer’s recommended acces-
hub nut engages the arbor for not less than four sories. Improper accessories may result in per-
(4) turns, and the hub nut is firmly tightened sonal injury or property damage.
before spinning the wheel.
16. Repair or replace any part that is damaged or worn
4. Read and understand this manual before operat- and that may cause unsafe balancer operation. Do
ing. Abuse and misuse will shorten the functional not operate damaged equipment until it has been
life. examined by a qualified service technician.
5. Be sure the balancer is properly connected to the 17. Never overload or stand on the balancer.
power supply and electrically grounded.
18. Do not allow untrained persons to operate
6. Do not operate equipment with a damaged cord machinery.
or if the equipment has been dropped or damaged
19. To reduce the risk of fire, do not operate equip-
– until it has been examined by a qualified serv-
ment in the vicinity of open containers or flamma-
iceman.
ble liquids (gasoline).
7. Do not let cord hang over edge of table, bench, or
20. Adequate ventilation should be provided when
counter or come in contact with hot manifolds or
working on operating internal combustion
moving fan blades.
engines.
8. If an extension cord is necessary, a cord with a
21. Keep hair, loose clothing, fingers, and all parts of
current rating equal to or more than that of the
body away from moving parts.
equipment should be used. Cords rated for less
current than the equipment may overheat. Care 22. Use equipment only as described in this manual.
should be taken to arrange the cord so that it will
23. Use only manufacturer’s recommended attach-
not be tripped over or pulled.
ments.
9. Keep guards and safety features in place and in
working order.

SAVE THESE INSTRUCTIONS

iv • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Introduction Servicing
This service manual contains the functional checks, Service should be performed only by COATS® trained
troubleshooting, adjustment, and part replacement and authorized service personnel. The troubleshooting
instructions for COATS® Models 950, 950 Pro Racer, and service procedures in this manual are arranged to
1025,1050 and 1055 Wheel Balancers. Exploded views, allow rapid and thorough service. The steps are prelim-
illustrations, and an indexed parts list facilitate parts inary inspection, functional checks, repair of failure,
location, ordering, and replacement. All adjustments replacement or adjustment, and functional checks.
and replacements can be rendered with mechanic's or Identification of replacement parts required can be
electrician's tools. accomplished by using the pictorial breakdown and
index in this manual. It is important that the functional
Safety Notes checks be performed in sequence and the problem iso-
High voltages, high torque motors, and high speed lated prior to attempting any adjustments or replace-
rotating wheels are present in coats wheel balancers. ments. If an adjustment or replacement is made, the
Follow the safety rules below while servicing a bal- entire functional checks must be performed success-
ancer: fully before the balancer can be considered available for
service.
1. Disconnect balancer from power source before
starting any part replacement or internal adjustment. Equipment Needed
2. Lower guard hood before starting cycle. 1. AC - DC / Volt - Ohm meter.
3. Do not wear neckties or loose clothing while serv- 2. Test Wheel - Domestic 14, 15 or 16-inch diameter
icing the balancer. x 6 - 6 1/2-inch wide steel wheel with a center hole
suitable for mounting with a back cone. A new 70
4. Be aware of hair length. If hair is long, wear it up
series tire properly mounted and inflated, balanced to
under a hat.
within 0.05 ounces should be part of this wheel
5. Mounting cones must be centered in wheel before assembly. The lateral run out of this wheel
tightening. The wheel must be forced up firmly against should be less than 1/8".
the faceplate. The hub nut must be engaged by a mini-
3. Mechanic's and electrician's tools.
mum of four (4) full threads. Tighten hub nut by rotating
the wheel and striking a spoke of the hub nut with the 4. Thread locking anaerobic (Loctite 242 or equiva-
heel of the hand. Failure to tighten the hub nut could lent).
result in serious injury.
5. Retaining compound (Loctite 601 or equivalent).
6. Dial indicator (runout gauge) with magnetic base,
Starret No. 25-431 or equivalent.
7. Modeling Clay.
8. Motor Controller PCB tester (# 8112708)
9. *Membrane Touch Panel Tester (8112929)

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 1

 Direct Drive
Voltage & Phase Checking 4. Plug the balancer to a power source.
Procedure 5. Use an Ohmmeter to check the resistance
1. Unplug the Balancer from the power source. between the frame of the Balancer and the building
ground. The resistance should be less than 1 ohm. If
2. Perform all voltage checks shown in the appropri- the resistance measurement is greater that one (1)
ate diagram and chart at the power receptacle. If one or ohm, check the power plug and frame connection for
all voltage measurements is faulty be sure to check the proper contact.
status of the circuit breakers that supply the Balancer.
3. Check from one of the power terminals to the
ground terminal to verify a ground is present. The volt-
age measurement should be approximately one half of
CAUTION
Operation with a defective ground circuit
the available voltage (i.e. 220V should read 110V). If the will create a shock hazard for the operator
reading is less that one half the available voltage, there and could damage the balancer's electron-
is not a ground present. Normal acceptable deviation is ics. Operation with a defective ground cir-
plus and minus 10%, damage can occur when voltage cuit may void warranty.
or amperage is beyond 10% design specs.
Note: If any faults are found in the above
procedure, it is the responsibility of the
owner. COATS authorized service personnel
are not responsible for wiring within the
building. Consult a licensed electrical con-
tractor for proper installation to local electri-
cal codes. Power outlets must be enclosed
in a floor raceway or overhead drop if pedes-
trian or equipment traffic can damage
power cord.

GROUND X Y Z GROUND A B

GREEN GREEN

RED BLACK
RED BLACK

WHITE

THREE PHASE VOLTAGE REQUIREMENTS / INFORMATION SINGLE PHASE VOLTAGE

REQUIREMENTS/ INFORMATION
208V/220V/230V 380V 460V
X-Y 195-250 370-420 420-480 208V/220V/230V
X-Z 195-250 370-420 420-480 A-B 195 - 250
Y-Z 195-250 370-420 420-480 Plug Hubbell
Plug Installed 5466-C
Installed Hubbell 2421 Hubbell 2431 Required Hubbell 5462 or
Required Hubbell 2420 or Hubbell 2430 or Mating Outlet Equivalent
Mating Outlet Equivalent Equivalent

2 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Preliminary Inspection 6. Install a 4 oz. weight on the outer rim of the test
wheel.
1. Check the power supply to the balancer. See the
procedure on page 6. 7. Choose the DYNAMIC balancing mode.
2. The Balancer should sit on all three (3) legs. Make 8. Lower the guard hood.
sure the legs have not filled with dirt, wheel weights, 9. Push the START button. The machine should now
or other foreign matter that may prevent a leg from cycle. If the machine does not cycle, see BALANCER
making contact with the floor. DOES NOT CYCLE.
3. The floor should be a solid flat surface that does 10. The balancer should come up to speed, coast for
not allow the balancer legs to set into a recess in the several revolutions, and then brake to a stop. If the
floor or sink into the floor itself. machine fails to brake and continues to coast, see BAL-
4. Check the operation of the cooling fan on the drive ANCER DOES NOT BRAKE.
motor. The fan should run as soon as the balancer is 11. The balancer should now have weight values and
powered. If the fan fails to run check the 1A breaker on position lights displayed.
the rear of the machine to see if it has tripped. If it has
tripped, reset it. If it will not reset, see FAN MOTOR 12. Position the wheel so the display for the center
DOES NOT RUN. position LED for the outside (right) plane is flashing.
5. Inspect cones, hub nut, pressure cup(s) , and 13. Note the position of the 4 oz. weight and the
threaded stud for damage. Missing cones or acces- weight readings for both planes.
sories should be replaced. 14. Perform five (5) spin cycles and note the posi-
Functional Checks tions and weight readings after each spin cycle. The
weight readings should repeat within .2 oz and the
Operational Check position within ± 1/2 inch. If they do not, see REPEATA-
1. Turn the power switch ON. The display should read BILITY PROBLEMS.
as follows;
Note: If the customer had problems with a
A, W, D - _0.0 specific wheel assembly only, make sure
Weight Display - _.00 there is no water or debris inside the tire.
Mode - Dynamic
Operator - A (Model 1050 only) Accuracy Check (Plane Separation)
Grams/Ounces - Last Selection 1. Remove the 4 oz. weight from the wheel.

If the display fails to light, see DISPLAY DOES NOT 2. Fine balance the test wheel to obtain 0.00 (+0.02)
LIGHT. weight readings on both displays. It may be necessary
to use modeling clay to counter balance small imbal-
2. Mount your test wheel (described in EQUIPMENT ances.
NEEDED. on the balancer.
3. Place a 4 oz. weight on the outside of the wheel.
3. Enter the wheel parameter data.
4. Press start. The readings for this cycle should be as
Note: If this is a Model 950 and the machine follows:
will not accept keypad entries, replace the
keypad. If this does not correct the problem Inner (Left) Plane = 0.00 + 0.20 oz.
replace the PCB and put the original keypad Outer (Right) Plane = 4.00 + 0.10 oz.
back in. Outer Position flashing= 4oz. at bottom-dead-center
± 1/2 inch
Note: If this is a Model 1025,1050 or 1055
and you do not get proper wheel parame- 5. Move the 4 oz. weight to the inside plane. Press
ters from the A & D Arm, see A & D ARM start. The reading should be as follows;
PROBLEMS. Inner (Left) Plane = 4.00 ± 0.10 oz.
4. If the balancer is in round off mode, press and hold Outer (Right) Plane = 0.00 ± 0.20 oz.
the SHIFT key and press ROUND OFF to enter the non- Inner Position flashing = 4oz. at bottom-dead-center
round off mode. ± 1/2 inch

5. If the balancer is in gram mode, press and hold the 6. If the above results are not achieved check the A,
SHIFT key and press GM/OZ key combination to set W, and D dimensions and perform the A & D ARM CAL-
the balancer to read in ounces. IBRATION and the WEIGHT SENSOR CALIBRATION.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 3

 Direct Drive
7. Check the placement of the distance tape, see the Calibration Procedures
DISTANCE GAUGE TAPE PLACEMENT PROCEDURE.
Weight Sensor Calibration
8. If specified results are not achieved see ACCU- 1. Turn the power switch ON.
RACY PROBLEMS.
2. Mount the test wheel to the machine.
Rotational Check (Use a Hub Centric Wheel)
1. Remove the 4oz. weight from the inner rim and 3. Enter the wheel parameters.
perform a fine balance to obtain 0.00 (+.02) weight 4. If the machine is in ROUND OFF mode, toggle it
readings on inner and outer plane. OFF by pressing and holding the SHIFT key and press-
2. Position valve stem at 6 o'clock. Loosen hub nut ing ROUND OFF.
just enough to allow the wheel to move. While holding 5. If the machine is not in ounce mode put it into
the faceplate so it cannot turn, rotate the wheel 90 ounce mode by pressing and holding the SHIFT key and
degrees relative to the faceplate. Tighten hub nut. pressing GM/OZ.
3. Press START. Weight readings should be 0.30 oz. or less. 6. Press and hold the SHIFT key and press CALI-
4. Repeat steps 2 & 3. At 180 and 270 degrees BRATE to enter the calibration mode. The display
weight readings should be .30 oz. or less. should read CAL 0.

5. If the specified results are not achieved see ROTA- 7. Push the START button. The machine should now
TIONAL PROBLEMS. cycle. This cycle is referred to as the zero spin cycle.
8. The balancer should come up to speed, coast for
several revolutions, and then brake to a stop.
9. The display should now read CAL 4.
10. Position the wheel so the display for the center
position LED for the outside (right) plane is flashing.
11. Add a 4 ounce weight to the 12 o'clock position
on the outside (right) of the wheel.
12. Push the START button.
13. The outer (right) weight display should read 4.00
± 0.02 oz. and the center position L.E.D. for the outside
(right) plane should be flashing when the weight is at
bottom dead center.
A & D Arm Calibration (Code 10)
1. Press and hold the SHIFT key and press 0. Then
press 1 followed by 0. The A pot reading is displayed on
the left weight display and the D pot reading is dis-
played in the right weight display. The reading for the A
pot should be between 0.05 and 0.30 and the D read-
ing should be between 0.40 and 0.80 when the arm is
in the park position. If the readings are not between the
given values see A and/or D PULLEY INSTALLATION.
2. Rotate the arm to the maximum diameter position.
While holding the arm in this position, press the MODE key.
3. Return the arm to the park position and press the
MODE key.
4. Pull the arm out to the test wheel and position it
into the radius of the wheel. While holding the arm
against the wheel you must enter the "distance" (A
dimension) to the test wheel (enter as 2 digits i.e. 5.8).
Before releasing the arm from this position, enter the
diameter of the wheel (D dimension as 3 digits i. e.

4 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
14.0). After these parameters have been entered, the Error Codes
weight displays will show 0 and the machine returns to
normal operating mode. The following is a list of error codes. When the bal-
ancer is cycled several operating parameters are
5. Return the arm to the park position. Then pull the checked. If one of these parameters is not within toler-
arm out and position into the radius of the wheel. The ance, the machine will generate one of the following
correct A and D readings should appear on the wheel error codes and use the weight reading LEDs to display
parameter display. These values would be within ± 0.20 the error code. An explanation of these codes and a
of the values entered in calibration. If the readings are troubleshooting procedure follows each code.
not within tolerance, check for slippage of the pot pul-
leys. If they are tight, see A & D ARM PROBLEMS. Err - Displayed when an entered parameter entered
is not in the acceptable range or not entered.
Stop-On-Top Calibration (Code 20/21)
Err Hod - Displayed when the hood switch is not
1. If the test wheel is not mounted to the machine,
closed (the hood is up, the hood switch is bad) when
mount it.
the machine cycle is started. Try closing the hood if the
2. Press and hold the SHIFT key and press 0. Then machine still gives this error. See WHEEL DOES NOT
press 2 followed by 0. This will toggle the machine into SPIN.
Stop on Top feature. The weight display should now
Err Hub - Displayed when the machine detects a no
read SOT ON. If the display now reads SOT OFF, repeat
“load” condition on the motor at start up. If there is a
the key sequence shown above.
wheel mounted on the arbor, check the mounting of
3. Add a 4 oz. weight to the outside of the test wheel. the wheel to make sure it is not “slipping”. See
REPEATABILITY PROBLEMS.
4. Press the START button.
Err Cal - Displayed when an error has occurred dur-
5. When the wheel stops press and hold the SHIFT
ing the calibration process. It can be caused by not
key and press 0. Then press 2 followed by 1 to cali-
placing the calibration weight on the wheel for one or
brate.
both spins, or a defective PCB. The code is generated
6. Repeat steps 4 and 5 until the wheel stops with by equal piezo outputs in consecutive spins.
the 4 oz. weight at approximately 6 o'clock.
Err 1 - Displayed when the wheel moves slowly
*Distance Gauge Tape Placement (Optimize A) when the start button is depressed. This can be caused
If the ACCURACY CHECK fails, try entering an A dimen- by a defective motor, defective contactor, motor control
sion .1 higher than the one used originally. If the plane board, or incorrect wiring of either of the previous. See
separation gets worse, try using an A dimension .1 lower WHEEL DOES NOT SPIN.
than the one used originally. If the plane separation gets
Err 2 - Similar to Err 1, this message is displayed
better, keep increasing or decreasing the A dimension
when the time to reach measurement speed is too
until an acceptable value is achieved. Calibrate the
long. This can be caused by a defective motor, defec-
machine and perform the ACCURACY CHECK. Repeat
tive contactor, motor control board, or incorrect wiring
this procedure until the ACCURACY CHECK produces an
of either. See WHEEL DOES NOT SPIN.
acceptable result. Move the distance tape to the posi-
tion to allow proper A dimension entry. Calibrate the bal- Err 3 - Displayed when no encoder pulse is detected
ancer using the new A dimension. after the start button is pressed (the motor did not
spin). This can be caused by incorrect wiring to the
encoder, contactor, motor control board, motor, PCB, or
safety interlock switch, If the drive motor did not start
see the troubleshooting procedure for WHEEL DOES
NOT SPIN. If the drive motor does begin to spin. See
OPTICAL ENCODER CHECKING PROCEDURE.
Err 4 - Displayed when the machine detects the
wheel rotation in the reverse direction. This can be
caused by incorrect encoder or motor phasing, motor
control board or a bad PCB. See WHEEL DOES NOT
STOP.
Err 5 - This message is displayed when the time to
brake the wheel to a stop at the end of the cycle is too

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 5

 Direct Drive
long. This can be caused by a bad contactor, motor con- *Function Codes
trol board or a bad PCB. See WHEEL DOES NOT STOP.
The following is a list of function codes with it’s
Err 6 - Displayed when there is no power to the description. Codes are entered into the balancer by
LEDs on the encoder. This can be caused by a defective pressing and holding the SHIFT key and then pressing
encoder or PCB, or improper encoder wiring. See and releasing the zero (0) key. At this time CDE will
OPTICAL ENCODER CHECKING PROCEDURE. appear in the left weight display. The two digit code is
Err 7 - Displayed when a time out occurs within the then entered and appears in the right weight display.
software. This can be caused by noise interference in There is a slight delay after the second digit is entered
the encoder circuit causing a signal sequencing error. at which time the display blanks temporarily and the
Check for a defective ground circuit or line filter prob- code is executed. There is approximately a 10 second
lem. window from the time CDE appears for the operator to
enter the 2 digit code. If the code is not entered in this
Note:The machine should be on a dedicated time, the code entry routine will automatically be ter-
circuit. minated.
Err 8 - Displayed when The most likely cause is noise 10 Calibrate the A & D arm.
interference. Check for a defective encoder cable, or
defective PCB. Check for a defective ground circuit or 20 Toggle stop-on-top ON or OFF.
line filter problem. 21 Calibrate stop-on-top.
Note:The machine should be on a dedicated 40 Displays the software revision on the weight dis-
circuit. play. The revision letter(s) is/are shown on the left dis-
Err 9 - This message is displayed when the speed of play and the revision level is shown on the right weight
the wheel has decreased at too fast a rate. This could display.
occur if the machine is extremely cold and a small 41 Indicates presence or absence of A & D arm and
wheels mounted on the shaft. stop-on-top hardware as dictated by the electronics. If
Err 10 - This message is displayed when a sequence there is no jumper connected between pins 15 and 17
error has occurred with the calibration of the A & D on the 18 pin connector in the harness, the left display
arm. See the A & D ARM CALIBRATION PROCEDURE. will show AR to indicate an A & D arm is present. If
there is a jumper between these pins, the left weight
Err 11 - This message is displayed when an unac- display will show NAR to indicate the absence of an A
ceptable A dimension was entered during the A & D & D arm. An analogous method is used for the stop-on-
arm calibration process. See the A & D ARM CALI- top feature. If there is no jumper between pins 16 and
BRATION PROCEDURE. 18, the right weight display will show SOT to indicate
Err 12 - This message is displayed when an unac- the presence of the stop-on-top hardware; otherwise
ceptable D dimension was entered during the A & D the display will show NST. It should be noted that the
Arm calibration process. See the A & D ARM CALI- presence or absence of the arm and stop-on-top is not
BRATION PROCEDURE. detected directly so if the jumpers are improperly
installed, incorrect information will be displayed.
Err 13 - This message is displayed when the A pot is
not adjusted properly. See REPAIR PROCEDURES FOR 42 Keyboard Test - After the code is entered all dis-
A & D ARM ASSEMBLY. plays will be blank. When a key is pressed the number
of the key or a description of the function is activated
Err 14 - This message is displayed when the D pot (MODE and SHIFT keys) is displayed on the wheel
is not adjusted properly. See REPAIR PROCEDURES parameter display. To exit the test, press and hold the
FOR A & D ARM ASSEMBLY. SHIFT key and press the zero (0) key.
Err 15 - *Displayed when the motor has gone over- 43 Display Test - All display segments are turned on
speed prior to breaking. This could be caused by a simultaneously including decimal points and individual
defective PCB, encoder, contactor or motor control LED's. The test may be terminated by pressing and
board, or incorrect wiring of either of the previous. holding the SHIFT key and then pressing and releasing
the zero (0) key. If the test is not terminated manually it
will terminated automatically.
44 Encoder TEST - The encoder count is displayed on
the right weight display and the left display is blanked.
The count should be zero (0) when the top-dead-center

6 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
indicators are flashing. As the shaft is rotated forward, Troubleshooting Section for
the count should increase. At the point where the bot- Models 950,1025,1050 & 1055
tom-dead-center indicators are flashing, the count
should be 128 and should continue to increase as the
Balancers
shaft is rotated in the forward direction. The maximum Introduction
count should be 255 which occurs just before the top- For balancers with Solid State Motor Controllers refer
dead-indicator begin to flashing as the shaft is being to that section only in the flow charts and wiring dia-
rotated forward. If the shaft is being rotated in the grams located in the back of this manual. The trou-
reverse direction, the above comments apply to top- bleshooting section of this manual makes use of flow
dead-center and bottom-dead-center. The count will charts. These flow charts will enable you to more
decrease from 255 to zero (0) as the shaft is being quickly and accurately locate the problem with the bal-
rotated in the reverse direction from top-dead-center. ancer. The main topics covered by these flow charts are
The test may be terminated by pressing and holding FAN MOTOR DOES NOT RUN, ACCURACY PROB-
the SHIFT key and then pressing and releasing the zero LEMS, ROTATIONAL PROBLEMS, REPEATABILITY
(0) key. PROBLEMS, DISPLAY DOES NOT LIGHT, BALANCER
DOES NOT CYCLE, and BALANCER DOES NOT
47 Cycle Count - This code displays the cycle count
BRAKE. These flow charts may refer you to another
of the board. The cycle count is displayed in the weight
section of the manual. If after a repair has been com-
display. The weight displays are treated as a single 6
digit display when displaying the count. pleted you encounter another or similar problem, refer
to the section that best describes the problem cur-
50 Exit Code - Code to escape from continues loop rently encountered. The flow charts are designed to
such as when displaying the transducer outputs. lead you to the most likely problems towards the top of
the chart, where possible. Hennessy Industries, Inc.
51 A & D Arm Adjustment - This code represents a
hopes this manual will help you provide the best and
subset of code 10 (A & D arm calibration). It allow the
most thorough service to our customers.
A & D potentiometers to be continuously monitored
with out having to do a complete calibration. The pri- The flow charts will refer to several voltage checks at
mary purpose is to enable the pulleys to be adjusted on various points. To avoid lengthy and confusing charts,
the potentiometer shaft. The A potentiometer voltage is the voltages shown on the blocks of the chart are nom-
displayed on the left weight display and the D poten- inal. To better define these voltages see the range chart
tiometer voltage is displayed on the right weight dis- below:
play. To exit this code, enter code 50.
120VAC = 98 to 125VAC
52 Piezo Output Test - 300 RPM. Used to verify that 220VAC = 198 to 240VAC
the output of the piezo are consistence through several 27VDC = 22 to 32VDC
spins. Refer to the checking procedure, piezo output.
53 Piezo Output Test - 200 RPM. Refer to the check-
ing procedure, piezo output.
99 Counter Reset - This code resets the counter on
the 950, 1025,1050, and 1055.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 7

 Direct Drive
Fan Motor Does Not Run (Contactor Model)

Is the power switch set No Turn the power

to the ON position? switch ON.
Yes
Replace the circuit breaker,
No
See the troubleshooting see Replacement Procedure.
Does the display light? procedure,
Yes
DISPLAY DOES NOT LIGHT.
Yes

Unplug the machine and disconnect

the fan motor lead from the circuit
Has the 1A breaker for Yes Reset the tripped breaker. Yes
breaker and reset the breaker. Plug in
the fan motor tripped? Did the breaker trip
the machine and turn the power switch
again?
No ON. Did the circuit breaker trip?
No
No
No Is the fan motor
running?
Yes

Return to FUNCTIONAL
CHECKS..

Is there 120VAC between the Yes

terminals marked 0V & 120V Replace the fan motor, see
on the transformer? Replacement Procedure.

No

Replace the transformer see

Replacement Procedure.

Accuracy Problems (Plane Separation)

Did you perform weight Perform weight sensor & A - D arm

No
sensor and A - D arm calibration, see Calibration
calibration? Procedures
Yes
Yes

Check/Replace piezo
Is weight reading Replace PCB Assembly,
No sensors. Did this correct No
accurate? see Replacement
problem?
Procedure.
Yes
No
No Replace optical encoder. Yes
Is position accurate?
Check for loose shutter
Yes wheel. Did this correct the
problem? Return to FUNCTIONAL
CHECKS.

8 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Rotational Problems (Contactor & Motor Controller Model)

Is the test wheel balanced No Fine balance test wheel

to 0.00 +.02oz? and test again.
Yes

Perform WEIGHT “SENSOR CALIBRA-

Did the balancer pass the No
TION procedure or refer to “ACCURACY
ACCURACY CHECK?
PROBLEMS” flow chart and test again.
Yes

Are there burrs, dirt, and/or

grease on faceplate, test wheel,
Yes Remove burrs and dirt
cones, or pressure cup prevent-
and test again.
ing perfect centering of the
wheel?
No

Are there worn or defective

cones, pressure cup, threaded Yes Replace defective parts
stud, backcone spring, or hub and test again.
nut?
No

Using a dial indicator check the

runout on the mounting surface of the Replace drive motor, see
Yes
motor face plate & the runout of the
arbor shaft. Are both total indicated Test again.
runouts greater than .001"?
No

Try mounting the wheel with a new

No
centering cone and spring. Does the
balancer now pass the rotational test?
Yes

Return to FUNCTIONAL
CHECKS.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 9

 Direct Drive
Repeatability Problems (Contactor & Motor Controller Model)

Mark the wheel & faceplate with Clean the faceplate and/or remove all
a piece of chalk and check after Yes
nicks. Make sure wheel is chucked
each spin. Is the wheel slipping tightly against faceplate
against the face plate?
No

Is the hub nut broken or Yes Replace the damaged

the cones damaged? part(s).
No

Is the balancer sitting on No Move balancer to a another

a hard flat surface.? location in the shop.
Yes

Is the balancer located near a Yes

piece of equipment that
causes the floor to vibrate?
No

Check the tension adjustment on the

Adjust springs. See step, 19 in
motor springs. See step 19 in the
No “DRIVE MOTOR REPLACEMENT Yes
"DRIVE MOTOR REPLACEMENT
PROCEDURE”.
PROCEDURE".
Did this correct the problem?
Where they adjusted properly?
No
Yes

Check the piezo wiring at the Bad Repair defective

piezo and at the P.C.B. plug for
connection(s).
good connections.
Good

Check/replace piezos, see the

procedure on page 32. Did
this correct the problem?
No

Check/replace the optical Yes Return to FUNCTIONAL

encoder. See the procedure on
CHECKS.
page 30 - 31. Did this correct
the problem?
No

Replace the PCB. See

Yes
Replacement Procedure. Did this
correct the problem?

No

Replace the drive motor

assembly. See
Replacement Procedure

10 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Display Does Not Light (Contactor Model)

Is the power switch set No Turn the power

to the ON position? switch ON.
Yes

Is the proper voltage and ground

present at the receptacle? See No Have the voltage supply
AC CheckingProcedure to the machine
corrected.
Yes

Reset the tripped breaker. If the

Has one of the 3A breakers on Yes
breaker trips again, replace the PCB.
the power panel tripped?
See Replacement Procedure
No

Disconnect the 2 RED wires

Is there between 200 & 230VAC
Yes from the circuit breakers. Is No Replace the transformer, See
between the terminals marked 0V
there 20VAC between these 2 Replacement Procedure
& 230V on the transformer?
RED wires? Reconnect wires.
No
Yes

Checks If either of the breakers are open,

Turn the power off and unplug the
Bad try resetting and rechecking. If
machine. Check the continuity of
the breaker remains open & does
the two (2) 3A circuit breakers.
not trip, replace the breaker.
Checks Good
Breaker
Trips
Connect the machine to a power
source and turn the power switch Replace the PCB. See
Yes
ON. Is there 20VAC between Replacement Procedure
pins 1 & 2 on the connector on
the right side of the PCB?
No
Checks
Good
Turn the power off and unplug the
machine. Check the continuity of Checks
the RED wires from the trans- Bad Repair or replace the
former pins 1 & 2 on the connec- defective wire or connection.
tor on the right side of the PCB.
Checks Bad
Turn the power off and unplug
the machine. Turn the power Checks Check the continuity of the wire
Good from the terminal marked 0V on
Is there 220VAC between switch to the ON position. Check
Yes the transformer to terminal 6 on
terminals 4 & 6 on the the continuity of the wire from the
forward contactor? 230V terminal on the transformer the forward contactor.
to terminal 4 (950) or terminal 64 Checks
No Bad Checks
(1050) on the forward contactor. Check the continuity of
Good
the power switch.
Checks Bad
Replace or repair the defec-
Yes tive jumper wire from the
Replace the power switch, See
Is there 220VAC between forward to brake contactor.
Replacement Procedure
terminals 4 & 6 on the
brake contactor?
No Check the continuity of the Checks Repair or replace
power cord from the terminals to Bad
the defective wire
the appropriate connection on
or connection.
the brake contactor.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 11

 Direct Drive
Balancer Does Not Cycle (Contactor Model)
To use the following chart you will need a tire and wheel assembly mounted on the balancer, the hood closed,
and the proper A, W, and D dimensions entered. If you are unable to manually enter the proper wheel dimensions,
replace the touch panel.

Does Not
Has one of the 1A circuit Yes Trip
Reset the breaker &
breakers on the rear of the Proceed to balance.
press the start button.
machine tripped?
Trips
No

Turn the power switch OFF and unplug the machine.

Replace the PCB.
Disconnect the white/violet wire from the forward Trips
See Replace
contactor, reset the breaker. Plug in the machine,
Procedure.
turn the power switch ON, & press the start button.
Does Not Trip

Replace the contactor. See

Replace Procedure.

Does the forward contactor Will the balancer cycle with

No Yes
close when the start button both the hood switch wires Replace the hood switch
is depressed? on the same terminal?
Yes No

Is there 27VAC between the two No Replace the transformer. See

orange wires on the transformer? Replace Procedure.
Yes

Turn the power switch OFF and unplug Yes Is there continuity from A1 of
the machine. Disconnect the connector the forward contactor to
from the right side of the PCB. Is there No terminal 6 of the connector on
continuity between A2 of each contactor? the right side of the PCB?
Is the proper voltage and Yes
ground present at the No Correct the voltage
receptacle? See page 6 for supply to the machine. Is there 3 to 5 or (5 to 7 new
No
the checking procedure. contactors)Ohms resistance
Yes between A1 & A2 on the
forward contactor?
Is there 230VAC on terminals 4 No Repair or replace defective Yes
to 6, 6 to 14, & 14 to 4 on the power cord or connections.
brake contactor? Replace the PCB.
Yes See Replace
Procedure.
Is there 230VAC on terminals 4 to
No Repair or replace defective
6, 6 to 14, & 14 to 4 on the
jumper wire or connections.
forward contactor?
Yes

*Manually close the forward

contactor & check for 230 VAC on
terminals 3 to 5, 5 to 13, & 13 to 3
Voltage Not
Present
Replace the contactor.
See Replace
Procedure.
CAUTION
of the forward contactor? Manually closing the contactor
Voltage to check voltage may cause the
Present wheel to spin at high speeds. To
avoid this from happening dis-
CONTINUED ON NEXT PAGE
connect the wires going from
the contactor to the motor.

12 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
CAUTION
CONTINUED FROM
Manually closing the contactor to check voltage may cause the
LAST PAGE wheel to spin at high speeds.To avoid this from happening dis-
connect the wires going from the contactor to the motor.

Is there 230VAC from terminals

Is this a Model 1050. Yes No Repair or replace defective
64 to 74, 74 to 84,& 84 to 64 on
jumper wire or connections.
No the forward contactor?
Yes

Voltage
*Manually close the forward contac- Not Replace the forward
tor & check for 230VAC on terminals Present
auxiliary contactor. See
63 to 73, 73 to 83, & 83 to 63 of the
Replace Procedure.
forward contactor.
Voltage Present

Turn the power switch OFF & unplug

the machine. Use an Ohmmeter to More Than Repair or replace
1 Ohm
check from terminal 53 on the defective jumper wire
forward contactor to terminal 74 on or connections.
the brake contactor.
Less Than 1 Ohm

More Than
Use an Ohmmeter to check from 1 Ohm
terminal 74 on the brake contactor to
terminal 2 on the forward contactor.
Less Than 1 Ohm

Manually close the forward More Than Replace the contactor.

contactor. Use an Ohmmeter to 1 Ohm
See Replace Proce-
check from terminal 2 to terminal 1
dure.
on the forward contactor.
Less Than 1 Ohm

After verifying the integrity of

If this is a single phase unit try Motor Does
Not Run
the motor connections at the
repalcing the capicator assy., contactor. Replace defective
See Replace Procedure. motor assembly. See
Replace Procedure.
*Manually close the forward
Yes contactor. Is there 230 VAC on No Repair or replace defective
Is this a Model 950.
terminals 3 to 5, 5 to 13, & 13 to 3 jumper wire or connections.
on the forward contactor?
Yes

Check connections at the wire Bad

Connection Repair or replace
nut where the three motor
defective connection.
wires are joined.
Good Connection
After verifying the integrity of
If this is a single phase unit try Motor Does
Not Run
the motor connections at the
replacing the capicator assy., contactor. Replace defective
See Replace Procedure. motor assembly. See
Replace Procedure.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 13

 Direct Drive
Balancer Does Not Brake (Contactor Model)
CAUTION
Does the wheel rotate clockwise Manually closing the contactor to
No
when the forward contactor is Reverse any two power leads check voltage may cause the wheel to
engaged at power source and re-test. spin at high speeds. To avoid this from
Yes
happening disconnect the wires going
from the contactor to the motor.
Does the brake contac- Yes Does the brake contactor Yes
tor ever close? remain closed?
No No

Has one of the 1A breakers on No Replace the optical encoder.

the rear of the machine tripped? See Replace Procedure.
Yes

Disconnect the wire from terminal A2 No Replace the contactor. See

of the brake contactor & check the coil Replace Procedure.
resistance from A1 - A2. Is the
resistance of the coil between 3 & 5
Yes Replace the PCB. See
Ohms (5 to 7 on new contactors)?
Replace Procedure.

Turn the power switch OFF &

unplug the machine. Disconnect
Is there 27VAC between A2 on the white/blue wire from A1 on the More Than Repair or replace
the brake contactor & terminal 4 No brake contactor. Use an Ohmme- 1 Ohm
defective wire or
on the connector on the right ter to check from A2 on the brake
connection.
side of the PCB? contactor to terminal A2 on the
Yes forward contactor. Connect the
white/blue wire.
Less Than 1 Ohm

Disconnect the wire from A2 on More Than

the brake contactor. Use an 1 Ohm
Ohmmeter to check continuity
from A1 on the brake contactor to
Less
terminal 5 on the connector on Than 1
the right side of the PCB. Ohm Replace the PCB. See
Connect the wire to terminal A2 Replace Procedure.
on the contactor.

Does the forward No Replace the optical encoder.

contactor ever open? See Replace Procedure.
Yes

Manually close the brake

Yes contactor. Is there a 230VAC No Replace the contactor. See
Is this a Model 950?
between terminals 3 to 5, 5 to Replace Procedure.
No 13, & 13 to 3 ?
Yes

Check the connections from Bad Repair or replace the defec-

the contactor to the motor. tive wire or connections.
CONTINUED ON Good
NEXT PAGE
Replace the drive motor. See
Replace Procedure.

14 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
CAUTION
Manually closing the contactor to check voltage
CONTINUED FROM
may cause the wheel to spin at high speeds. To
LAST PAGE avoid this from happening disconnect the wires
going from the contactor to the motor.

Does the Balancer trip a circuit

Yes Check the bridge rectifiers.
breaker on the electrical panel
See Checking Procedure.
when it starts the brake cycle?
No

Manually close the brake Manually close the brake

contactor. Is there 220VDC on No contactor. Is there 220VAC No Replace the contactor. See
between terminals 13 & 54 on between terminals 3 & 5 on Replace Procedure.
the forward contactor? the lower contactor?
Yes Yes

Turn the power switch OFF and unplug

the balancer from the power source.
Manually close the brake contactor. Use Replace the auxiliary
No
an Ohmmeter to check between termi- brake contactor. See
nals 53 & 54 and between terminals 83 Replacement Procedure.
and 84 on the brake contactor. Is there
less than 1 Ohm on both checks?
Yes

Turn the power switch OFF. Manually close the brake contac-
tor. Use an Ohmmeter to check these connections for conti-
nuity on the brake contactor, 63 to 64 & 73 to 74. If your meter Use an Ohmmeter to check for continuity on the following
fails to read 0.0 ohms, replace the auxiliary (piggy back) connections. If your meter fails to register any resistance,
contactor on the brake contactor. While the contactor is closed repair or replace the defective wire or connection(s) associ-
also check terminals 1 to 2 on the brake contactor. If your meter ated with the terminals just checked.
fails to register any resistance, replace the primary contactor.
Forward contactor terminal 13 to brake contactor terminal 84.
Use an Ohmmeter to check the following connections. If your Forward contactor terminal 54 to brake contactor terminal 54.
meter fails to register 0.0 ohms, repair or replace the defective Brake contactor terminal 83 to both rectifiers terminal “+”.
wire or connection(s) associated with the terminals just checked. Brake contactor terminal 53 to both rectifiers terminal “-”.
Brake contactor terminal 5 to all 4 rectifier terminals “~”.
Forward contactor terminal 1 to brake contactor terminal 2. (Only one terminal on each contactor will give a reading.)
Forward contactor terminal 5 to brake contactor terminal 1. Brake contactor terminal 13 to 2 rectifier terminals “~” that did
Forward contactor terminal 3 to brake contactor terminal 63. not render a reading in the previous check.
Forward contactor terminal 73 to brake contactor terminal 64.
Forward contactor terminal 53 to brake contactor terminal 74.
Forward contactor terminal 83 to brake contactor terminal 73.

After verifying the integrity of

the motor connections to the
contactor, replace the motor
assembly. See Replacement
Procedure.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 15

 Direct Drive
A & D Arm Problems

Return the arm to the

Power cycle the “Home” position. The end of
Yes Has the arm returned all No
machine, does the the arm should be resting
the way to the bushing?
Balancer “Beep” against the guide bushing.
for 20 seconds? Yes Power cycle the machine.
No

Key “Shift + 0, 1, 0”. Adjust the A - D Arm. See the

Does the potentiometer No
“A” & “D” Pulley installation
for “A” (left weight display) procedures.
reading between .05 and
.30 & the “D” (right weight Adjustments Completed
display) reading between
0.4 and 0.8?
Yes
Calibrate the A - D Arm, See
Calibration Procedure.

Yes Does the balancer accept

Does the balancer hold the No entry from the A - D Arm?
initial “A” & “D” dimensions?
No
Yes

Check the A-D Arm for proper

placement of the Distance Tape. No Replace the PCB. See
See DISTANCE GAUGE TAPE Replacement Procedure.
PLACEMENT.
Yes

Does the “A” dimension

entered by the A-D arm No
match the distance shown
on the Distance Tape?
Yes

Does the “D” dimension

entered by the A-D Arm No
match the diameter
shown on the tire?
Yes

Proceed to balance.

16 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Checking Procedures *Optical Encoder (Code 44)
1. Press and hold the SHIFT key and press 0. Then
*Bridge Rectifiers press 4 followed by 4. Rotate the wheel, the readings
1. Turn the power switch OFF and unplug the in the display window should change from 000 to 255.
machine. If not check the shutter disc for blockage then check the
2. There are several type of rectifiers with different following voltages.
types of terminal identification. Use the drawing below 2. When reading the voltages on the white & green
that best represents the type oof rectifier you are wires, turn the faceplate slowly by hand. The low volt-
checking age must be less than .7VDC. The high voltages must
Red .45 Blk be greater than 4.0VDC.
Blk OL Red
3. Voltage readings are taken with all optical encoder
AC
Volt Leads
- wires connected.
.45 OL
OL .45 Lead Color Voltage
AC
+ Green to Violet (GND) - 2.4 ± .5VDC
Yellow to Violet - Less than .7VDC; greater
Red OL Blk than 4VDC
Blk Red
.45 Blue to Violet - Less than .7VDC; greater
than 4VDC
Typical readings,
Typical readings,
youryour
VOM VOMreadings
*Motor Circuit Testing
mayreadings may
very slightly. The following diagram will be useful when trou-
very slightly bleshooting the motor circuit of a 1004, 1050, or 6401
balancer (contactor style).
- It allows you to troubleshoot just the motor using the
motor wiring diagram or the complete circuit using the
AC AC
Forward or Braking diagrams. The readings may vary
slightly depending on your ohm meter but the three
readings should be consistently the same.

+ It may be useful to check the readings on a working

balancer so you will know what your meter reads
3. Remove all wires from the rectifier being checked.
before trying to repair a nonworking balancer.
4. Set Ohmmeter to the diode check mode, if so
Solid State Balancer motors may be checked in a sim-
equipped. If your meter does not have this mode, use
ilar manner by unplugging the motor connector and
the highest range ohm scale.
reading across the three motor wires, you should have
5. Plug the red lead into the meter in the connection the same readings across L1 to L2, L2 to L3, L1 to L3.
marked ohms.
6. Plug the black lead into the meter connection
marked common or ground.
CAUTION
Remember to unplug the balancer before
7. Place the black lead of your meter on the terminal
using this procedure.
marked (+).
8. Use the red lead of your meter to check to the
other two (2) AC terminals.
9. The readings from these terminals should not rep-
resent a short (0.00). If at any time during this proce-
dure you obtain a reading that represents a short, the
rectifier must be replaced.
10. Place the red lead of your meter on the terminal
marked (-).
11. Use the black lead of your meter to check to the
other two (2) AC terminals.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 17

 Direct Drive
*Motor Circuit Diagram

WARNING
Disconnect AC power before taking readings.
The motor may be checked individually using the To check the braking circuit, disconnect the rectifier
motor wiring diagram above. The complete spin circuit from the 83. Place your ohms leads across 53 and 83.
may be checked by placing your ohm leads across Press and hold the brake contactor and check the read-
L1&L2, L2&L3, L1&L3. Press and hold the spin contac- ing. It should be approximately 24 ohms (5 x 4.8). If the
tor in while taking the reading. The readings should be reading is incorrect use the Brake Circuit diagram to
approximately the same (4.8 ohms + or - 1 ohm). If one check for a bad connection, bad wire crimp, or high
leg reads different than the other two, use the Forward resistance through the contactor or motor winding.
Circuit diagram and check for a bad connection, bad
wire crimp, or high resistance through the contactor or
motor winding.

18 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*Piezo Output Note: Rust, corrosion, and trash under the
The piezo out-put test can be used to help diagnose piezo ball or between the piezo and the
problems or failures with piezos on the 950/1050, 1025 chassie can cause a bad ground and make
(Limited Edition), 850, and 700 balancers. When the the readings fluctuate. Cleaning, reinstalla-
test is activated the weight display will show four dif- tion, adjusting to proper torque and cali-
ferent readings as the Dynamic, RV, Alloy 1, and Alloy 2 brating may be all that is necessary for
LED's alternately light up. The values needed are the repair.
Dynamic (1st LED) and Alloy 1 (3rd LED). Dynamic Note: For 850 use the Dynamic LED for the
value is the amplitude, or signal strength, of the left left reading and Static LED right reading.
piezo. Alloy 1 is the amplitude of the right front and rear
piezo added together (except for 850 that only has two For the 700 balancer use the Dynamic LED for the left
piezos). It is the consistency of the readings through and Alloy LED for the two right piezo's.
five or six spins that is important, not the value of the When checking these two balancers only use the left
readings. display readings (rounded off to 3 places).
To use the codes perform the following steps: Code 52 (Shift 0 - 52) Code 27
1. Mount a balanced wheel on the balancer with a 4 950/1050, 1025, 700 850
oz. weight on the outside, enter the wheel parameters.
2. Enter the piezo test code for the model balancer
being tested. Ignore the initial set of values displayed.
3. Spin the wheel by closing the wheel guard and/or
pressing the spin button. When the balancer stops,
write down the values when the Dynamic and Alloy 1
LED's are on. These values will be slightly different on
each balancer. Typical readings for 950/1050 balancer
Left Display 1150 Right Display 1050
4. Repeat step 3 above for five more spins.
Remember you are looking for consistency of the read-
ings.
5. If the Dynamic value fluctuates more than +/- 10,
check and/or replace the left piezo.
Note: The following steps will allow both
right piezos to be tested individually by
unpluging one at a time.
(The 850 only has two piezos and may be tested by
reviewing the left and right readings.)
6. If the Alloy 1 reading fluctuates more than +/- 10
test the right front piezo by unplugging the right rear
piezo and repeating step 4.
7. If the reading is stable the right front piezo is good.
Check and/or replace the right rear piezo after testing.
8. If the reading in step #7 fluctuates, check and/or
replace the right front piezo.
9. Reverse steps #6 and #7 to test the right rear
piezo. Both piezos should be checked individually
before replacing either piezo.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 19

 Direct Drive
Replacement Procedures Section Front Panel/Printed Circuit Board Assembly
for Models 950,1025, 1050, & Replacement
1055 Balancers 1. Unplug the balancer.

The procedures in this section will aid in replacing 2. Check contactor coil resistances, see the proce-
major sub-assemblies of the balancer. dure on page 24.

Do not disassemble, adjust or replace any part before 3. Remove the four (4) 6-32 acorn nuts on the back of
performing the PRELIMINARY INSPECTION and the pod.
FUNCTIONAL CHECK PROCEDURES. These proce- 4. Disconnect the plugs on the PCB Assembly.
dures, along with the troubleshooting flow charts, will
isolate the necessary adjustment or replacement. 5. Remove the Front Panel/Printed Circuit Board
Perform checks in the order listed and exactly as spec- Assembly.
ified. 6. Connect the plugs to the new PCB Assembly.
Refer to the illustrated parts breakdowns and parts 7. Line up the four (4) 6-32 studs on the back of the
lists in the back of the manual for parts identification. Touch Panel/Aluminum Back Panel with the four (4)
Standard commercial fittings and fasteners are used holes in the pod and install.
throughout and should be obtained locally.
8. Install the four (4) 6-32 acorn nuts.
Check all interconnecting wiring and connectors
when an electrical malfunction is indicated. Check all 9. Plug in the balancer.
fittings and fasteners when a mechanical malfunction is 10. Perform the 950/1050 Balancer Test Procedure.
indicated.
11. Perform the FUNCTIONAL CHECKS.
Front Panel/Printed Circuit Board Assembly
Important: Never replace the printed circuit Touch Panel/Aluminum Back Panel And PCB
board without first checking the contactor Assembly
coil resistance whenever any of the follow- 1. Unplug the balancer.
ing symptoms occur. Shorted contactor 2. If the PCB is being replaced, check contactor coil
coils will result in failure of the new printed resistances, see the procedure on page 24.
circuit board.
3. Remove Front Panel/PCB Assembly from the pod.
1. Displays do not light.
4. Remove the eight (8) screws holding the PCB
2. Drive motor does not start. Assembly to the Touch Panel/Aluminum Back Panel.
3. Drive motor does not stop. 5. Disconnect the plug going to the PCB Assembly.
Contactor Coil Resistance Measurement 6. Replace the defective Touch Panel/Aluminum Back
1. Unplug the balancer. Panel or PCB Assembly and connect the plug from the
2. Disconnect the plug from the right side of printed Touch Panel/Aluminum Back Panel to the PCB
circuit board assembly. Assembly.

3. Set ohmmeter to lowest scale. Note: Make sure there are no twists or kinks
in the cable.
4. Measure the resistance from terminals A1 to A2
on both the start and brake contactors. 7. Install the eight (8) screws holding the PCB assem-
bly to the Touch Panel/Aluminum Back Panel.
5. Resistance should be 3 to 5 ohms (5 to 7 ohms on
newer contactors with metal plate on the bottom), if 8. Install Front Panel/PCB Assembly to the pod.
not, replace the contactor. 9. Plug in the balancer
New Repair Procedure: The models 950,1025,1050, 10. Perform the FUNCTIONAL CHECKS.
and 1055 are different from other COATS balancers in
that the Front Panel/ Printed Board assembly has been
designed so that the PCB Assembly and the Touch
Panel/ Aluminum Back Panel can be replaced sepa-
rately. Refer to the Trouble Shooting section for diag-
nostic instructions for isolating the defective assembly.

20 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
Hood Magnet On/Off Switch
1. Remove the rubber hood stop from the hood 1. Unplug the balancer.
bracket on the chassis.
2. Remove weight tray and weight tray shield.
2. Lean the hood back as far as it will go.
3. Disconnect wiring to on/off switch.
3. Remove the magnet from the hood bar.
4. Squeeze the retainers at the top and bottom of the
4. Install the new magnet. switch and push it through the opening in the power
panel and chassis.
5. Place the hood in the down position and install the
rubber hood stop. 5. Install new on/off switch.
6. Check to make sure that the motor starts with the 6. Connect wires.
hood down but not with it up.
7. Install weight tray and weight tray shield and plug
7. Perform the FUNCTIONAL CHECKS. in balancer.
Magnetic Hood Switch 8. Perform the FUNCTIONAL CHECKS.
1. Unplug the balancer.
Circuit Breakers
2. Remove two (2) 6-32 x 1/2 screws holding hood There are four (4) circuit breakers three (3) breakers if
switch to hood bracket and remove hood switch. the unit has a Motor Controller PCB) located on the top
of the Power Panel. Refer to the Wiring Diagrams for
3. Disconnect two (2) wires going to hood switch.
circuit location. The replacement procedure for each is
4. Connect wires to new hood switch and install. the same.
5. Plug in the balancer. 1. Unplug the balancer.
6. Check to make sure that the motor starts with the 2. Remove weight tray and weight tray shield.
hood down but not with it up.
3. Disconnect wiring to circuit breaker.
7. Perform the FUNCTIONAL CHECKS.
4. Squeeze the retainers on both sides of the circuit
*Mechanical Hood/Interlock Switch breaker and push it through the power panel and chas-
1. Unplug the balancer. sis.
2. Drill out the four (4) pop rivits holdint the sheld in 5. Install new circuit breaker.
place. 6. Connect wires.
3. Remove the screw and nut holding the switch. 7. Install weight tray and weight tray shield and plug
4. Disconnect two (2) wires going to hood or interlock in balancer.
switch. 8. Perform the FUNCTIONAL CHECKS.
5. Connect wires to new hood or interlock switch and
install.
Note: The two (2) switches are wired differ-
ently, one is normally open and the other is
normally closed. Refer to the wiring diagram
for correct wiring.
6. Replace the sheld.
7. Plug in the balancer.
8. Check to make sure that the motor starts with the
hood down but not with it up.
9. Perform the FUNCTIONAL CHECKS.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 21

 Direct Drive
Transformer Note: For ease of installation, the motor wires
1. Unplug the balancer. are numbered corresponding to the motor ter-
minal numbers on the wiring diagram.
2. Remove weight tray and weight tray shield.
9. Install Power Panel.
3. Remove the two (2) 8-32 x 1/2 screws and remove
the transformer from the Power Panel. 10. Pull power cable out of chassis and tighten power
cable clamp.
4. Record wire color and corresponding transformer
terminal numbers. 11. Install weight tray and weight tray shield and plug
in balancer.
5. Disconnect wiring to transformer.
12. Perform the FUNCTIONAL CHECKS.
6. Connect wiring to transformer.
Auxiliary Contactor Block
1. Perform steps 1 through 4 of Contactor
CAUTION Replacement Procedure.
Transformer wiring must be transferred to 2. Disconnect wiring from auxiliary contact block.
new transformer exactly as connected previ- 3. Lift the white lever that is on the top of the contac-
ously. Failure to perform this important step tor block and slide the contactor block off the contactor.
properly may result in damage to trans-
former, balancer wiring, or printed circuit 4. Install new contactor block and connect wiring.
board. (See Wiring Diagram ).
7. Install new transformer to Power Panel.
8. Install weight tray and weight tray shield and plug
CAUTION
Follow the same precautions as outlined in
in balancer
step 8 of the CONTACTOR REPLACEMENT
9. Perform the FUNCTIONAL CHECKS. PROCEDURE.
Contactor 5. Perform steps 9 through 12 of CONTACTOR
1. Unplug the balancer. REPLACEMENT PROCEDURE.
2. Remove weight tray and weight tray shield. Bridge Rectifiers
Note: See checking procedure on page 23.
3. Loosen the power cable clamp on the back of the chas-
sis and push one or two feet of cable into the chassis. 1. Unplug the balancer.
4. Remove three (3) 6-32 x 1/2 screws holding power 2. Remove weight tray and weight tray shield.
panel to chassis and set power panel on top of bracket
3. Identify and record wire locations.
in center of balancer to facilitate wire removal.
4. Disconnect wiring from bridge rectifier.
5. Record the wire numbers and the corresponding
contactor terminal location. 5. Remove the 8-32 x 3/4 screw holding the bridge
rectifier to the power panel.
6. Disconnect wires at contactor.
6. Place a small amount of thermal grease on back of
7. Loosen two (2) 8-32 x 3/4 screws holding contac-
the bridge rectifier and install the new bridge rectifier.
tor and slide out contactor.
7. Connect wiring.
8. Install new contactor and connect wiring.

CAUTION CAUTION
The wires must be transferred to new bridge
Contactor wiring must be transferred to new
rectifier exactly as connected previously.
contactor exactly as connected previously.
Failure to perform this important step can 8. Plug in the balancer.
result in damage to contactor, drive motor,
9. Check bridge rectifier as outlined in TROU-
balancer wiring and printed circuit board.
BLESHOOTING SECTION.
(See Wiring Diagram).
10. Install weight tray and weight tray shield.
11. Perform the FUNCTIONAL CHECKS.
22 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055
 Direct Drive
A & D Arm Assembly Rotary Shutter
Note:The Model 950 uses a manual Distance 1. Unplug the balancer.
Gauge Assembly. The model 1050 uses an
2. Remove weight tray and weight tray shield.
automatic Distance (A) and Diameter (D)
Gauge Assembly. These assemblies are 3. Remove rear end bell cover.
repairable. Refer to the illustrated parts
4. Remove the 3/8 by 3/8 shoulder bolt and the rotary
breakdown and parts lists in the back of this
shutter.
manual for individual parts identification.
Note: Some motors will have a plastic shim,
1. Unplug the balancer.
part number 8-143988 between the rotor
2. Remove weight tray and weight tray shield. and the rotary shutter. Leave this shim in
place when replacing the rotary shutter.
3. Model 1050, disconnect plugs.
5. Install the new rotary shutter.
4. Remove three (3) 1/4-20 flange nuts holding gauge
assembly. 6. Put Loctite 242 or equivalent on the 3/8 shoulder
bolt threads, install and tighten.
5. Remove gauge assembly.
7. Install rear end bell cover.
6. Install new or repaired gauge assembly.
8. Install weight tray and weight tray shield and plug
7. Model 1050, connect plugs.
in balancer.
8. Plug in the balancer.
9. Perform the FUNCTIONAL CHECKS.
9. Model 1050, perform A & D Arm Calibration
Procedure.
Optical Encoder Assembly
1. Unplug the balancer.
10. Install weight tray and weight tray shield.
2. Remove weight tray and weight tray shield.
11. Perform the FUNCTIONAL CHECKS.
3. Remove rear end bell cover.
Fan Motor Assembly
4. Remove rotary shutter.
1. Unplug the balancer.
5. Disconnect optical encoder plug.
2. Remove weight tray and weight tray shield.
6. Slide optical encoder from aluminum rear end bell
3. Disconnect fan motor plug.
casting.
4. Remove rear end bell cover.
Note: Some motors will have a plastic shim
5. Remove the two (2) 8-32 nuts holding the fan behind the optical encoder. Leave this shim
motor to the drive motor and remove the fan motor in place when replacing the optical encoder.
assembly.
7. Install new optical encoder.
6. Install new fan motor assembly and tighten nuts.
8. Install rotary shutter.
7. Connect fan motor plug.
9. Install rear end bell.
8. Install weight tray and weight tray shield and plug
10. Connect optical encoder plug.
in balancer.
11. Install weight tray and weight tray shield and plug
9. Perform PRELIMINARY INSPECTION and FUNC-
in balancer.
TIONAL CHECKS.
12. Perform the FUNCTIONAL CHECKS.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 23

 Direct Drive
Drive Motor Assembly 19. Tighten the Nyloc nuts until the distance from the
Hennessy now has available a service motor kit for top of the motor cradle to top of the piezo spring
the 950/1025/1050/1055 Contactor & Solid State retainer is two (2) inches.
Balancers which will allow everyone to use one part 20. Connect fan motor plug.
number when ordering a motor. The kit will be a com-
plete motor assembly, hardware bag, & wiring instruc- 21. Connect optical encoder plug.
tions. The hardware bag will contain wires, wire nuts, 22. Connect drive motor wires to the contactor and
spade connectors & a green phoenix connector. It will auxiliary contactor block.
require a crimping tool to crimp the spade connectors
to motor wires as needed for contactor style units. Note: Each motor wire is numbered corre-
Refer to the Motor Service Kit instructions in this man- sponding to the motor terminals on the
ual for additional information. wiring diagram.
1. Unplug the balancer. 22. Install the weight tray, weight tray shield and
motor cover and plug in the balancer.
2. Remove weight tray, weight tray shield and motor
cover. 23. Perform the FUNCTIONAL CHECKS.
3. Disconnect fan motor plug. Piezo Assembly
Note: See checking procedure in this manual
4. Disconnect optical encoder plug.
before replacing piezos.
5. Disconnect each motor wire where it is connected
1. Unplug the balancer.
to the contactor and auxiliary contactor block.
2. Remove weight tray, weight tray shield and motor
6. Remove the four (4) piezo springs and piezo spring
cover.
retainers.
3. Remove the four (4) 3/8 - 16 Nyloc spring retaining
7. Remove the two (2) 5/16 - 18 X 1 washer head
nuts, spring retainers and piezo springs.
screws and lift out the motor assembly.
4. Remove the two (2) 5/16 - 18 X1 washer head
8. Position the motor on its side or back and remove
screws.
the four (4) 3/8 - 16 washer head screws holding the
flex plate to the motor. 5. Disconnect the fan motor and optical encoder plugs.
9. Remove the flex plate. 6. Note wire colors and disconnect wires to piezo
assemblies.
10. Remove the four (4) 3/8 - 16 washer head screws
holding the cradle to the motor. 7. Lift up on the motor and twist and lift the piezo
assemblies to remove from the chassis.
11. Remove the cradle from the motor.
Note:The piezo assemblies used in the mod-
12. Apply Loctite 242 to the threads of the 3/8 -16
els 950 and 1050 balancers are different from
washer head screws and install the cradle on the new
other Coats balancers in that they are held
motor.
in position by studs in the bottom of the
13. Clean and apply Loctite to the surface of the flex piezo carriers that fit into holes in the chas-
plate and the cradle where they mate. sis. New piezos have the ball molded into
the top casting.
14. Apply Loctite 242 to the threads of the 3/8 - 16
washer head screws and install the flex plate on the 8. Use emery cloth to clean the mounting surfaces of
cradle. the piezo assemblies and chassis, install new piezo
assemblies and connect wires.
15. Ensure balls are inserted into each piezo assembly.
9. Install the two (2) 5/16 - 18 X1 washer head
Note: Current piezos have the ball molded
screws.
into the top casting
10. Install piezo springs, spring retainers and Nyloc
16. Install motor.
nuts.
17. Install 5/16 - 18 X 1 washer head screws holding
11. Tighten the Nyloc nuts until the distance from the
flex plate to chassis.
top of the motor cradle to the top of the retainer is two
18. Install piezo springs, piezo retainers and 3/8 - 16 (2) inches.
Nyloc nuts.
12. Connect the fan motor and optical encoder plugs.

24 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
13. Install weight tray, weight tray shield and motor Signal Harness
and plug in balancer. 1. Unplug the balancer.
14. Perform the FUNCTIONAL CHECKS. 2. Remove weight tray and weight tray shield.
Capacitor Assembly 3. Remove Front panel /PCB Assembly.
1. Unplug the balancer.
4. Disconnect plugs from PCB assembly.
2. Remove weight tray and weight tray shield.
5. Disconnect signal harness connections inside
3. Disconnect plug to capacitor assembly. chassis.
4. Remove four (4) 6 - 32 X 1/2 screws holding capac- 6. Cut tie wrap securing signal harness to chassis.
itor panel to chassis
7. Pull harness out of hole in back of chassis and then
5. Install new capacitor assembly. up through pod support tube and out through pod.
6. Connect plug. 8. Install new signal harness.
7. Install weight tray, weight tray shield and plug in 9. Connect signal harness connections inside chas-
balancer. sis. Refer to wiring diagram.
8. Perform PRELIMINARY INSPECTION and FUNC- Note: All signal harnesses come wired for
TIONAL CHECKS. the model 950. When installing a signal har-
ness in a model 1025 remove the jumper
Capacitor between 15 to 17. For a1050/55 remove the
1. Unplug the balancer. jumpers from terminals 15 to 17 and 16 to 18
2. Remove weight tray and weight tray shield. on the 18 pin connector.
3. Disconnect plug to capacitor assembly. 10. Connect plugs to PCB assembly.
4. Remove three (3) 6 -32 X 1/2 screws holding capac- 11. Install Front Panel/PCB assembly.
itor clamps to capacitor panel and remove capacitor 12. Install weight tray and weight tray shield.
clamps.
13. Perform the FUNCTIONAL CHECKS
5. Remove capacitors. Note wire locations, discon-
nect wires from capacitors and transfer wires to new
capacitors
Note: Only one capacitor should have a resis-
tor connected across its terminals. If both
new capacitors have resistors, cut one out.
6. Install capacitors.
7. Connect plug.
8. Install weight tray, weight tray shield and plug in
balancer.
9. Perform PRELIMINARY INSPECTION and FUNC-
TIONAL CHECKS.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 25

 Direct Drive
Repair Procedures for the A & D A Potentiometer Replacement
Arm Assembly 1. Remove the A pulley, see the procedure under
topic A PULLEY REMOVAL on page 34.
A Pulley Removal
1. Rotate the pulley counterclockwise and remove 2. Unplug the three (3) wires form the A potentiome-
the brass stop and cable from the catch groove on the ter from the wiring harness.
pulley. 3. Remove the wires for the A potentiometer from
2. Loosen the cap screw on the pulley and carefully the A & D Bracket.
slide the pulley and return spring from the shaft of the 4. Remove the potentiometer retaining nut lock-
potentiometer. washer, and the potentiometer.
A Pulley Installation/Adjustment (Code 10) 5. Install the new potentiometer, lockwasher, and
1. Locate the return spring onto the A pulley. Install retaining nut.
the tension spring to the retaining pin on the pulley,
6. Install the potentiometer wires to the A & D
ensuring that the spring coils counterclockwise from
Bracket using a small mount of silicone sealer/adhe-
the inside to the outside.
sive.
2. Catch the outside loop on the end of the return
7. Connect the wires for the A potentiometer to the
spring onto the tension pin on the A & D bracket.
wiring harness.
3. Slide the A pulley onto the shaft of the poten-
8. Install the A pulley, see the procedure under A
tiometer.
PULLEY INSTALLATION in this guide.
4. Rotate the A pulley counterclockwise one (1) turn
and loop the cable from the distance gauge around the D Pulley Removal
pulley. 1. Rotate the pulley clockwise and remove the brass
stop and cable from the catch groove on the pulley.
5. Install the cable and brass stop assembly into the
groove on the pulley. 2. Loosen the cap screw on the pulley and carefully
slide the pulley and return spring from the shaft of the
6. Locate the A pulley on the shaft of the poten- potentiometer.
tiometer such that the cable assembly from the dis-
tance gauge is located in the center of the pulley
groove and the cable is not contacting the edge of the
pulley groove.
7. Press and hold the SHIFT key and press 0. Press 1
and the 0.
8. Using a small screw driver, rotate the end of the
potentiometer shaft until the left weight display reads
between .10 and .20.
9. Lock the pulley in place by tightening the cap
screw on the pulley.

CAUTION
Do not over tighten. Over tightening may
cause the pulley to crack.
10. See A & D ARM CALIBRATION PROCEDURE on
page 10 - 11.
11. See WEIGHT SENSOR CALIBRATION PROCE-
DURE on page 9 - 10.

26 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
D Pulley Installation/Adjustment (Code 10) D Potentiometer Replacement
1. Completely back off the plunger stop pin. 1. Remove the D pulley, see the procedure under
topic D PULLEY REMOVAL.
2. Locate the return spring onto the D pulley. Install
the tension spring to the retaining pin on the pulley, 2. Unplug the three (3) wires form the D potentiome-
ensuring that the spring coils clockwise from the inside ter from the wiring harness.
to the outside.
3. Remove the wires for the D potentiometer from
3. Slide the D pulley onto the shaft of the poten- the A-D Bracket.
tiometer.
4. Remove the potentiometer retaining nut, lock-
4. Catch the outside hook on the end of the return washer, and the potentiometer.
spring onto the tension pin on the A & D bracket.
5. Install the new potentiometer, lockwasher, and
5. Rotate the D pulley clockwise approximately 3/4 of retaining nut.
a turn and loop the cable from the distance gauge
6. Install the potentiometer wires to the A-D Bracket
around the pulley.
using a small mount of silicone sealer/adhesive.
6. Install the cable and brass stop assembly into the
7. Connect the wires for the D potentiometer to the
groove on the pulley.
wiring harness.
7. Locate the D pulley on the shaft of the poten-
8. Install the D pulley, see the procedure under D
tiometer such that the cable assembly from the dis-
PULLEY INSTALLATION.
tance gauge is located in the center of the pulley
groove and the cable is not contacting the edge of the
pulley groove.
8. Press and hold the SHIFT key and press 0. Press 1
and the 0.
9. Using a small screw driver, rotate the end of the
potentiometer shaft until the right display reads
between .50 and .60.
10. Lock the pulley in place by tightening the cap
screw on the pulley.

CAUTION
Do not over tighten. Over tightening may
cause the pulley to crack.
11. Turn the plunger pin out until the D pot value is
0.05 to 0.10 than the value that was obtained in step 9
of this procedure.
12. See the A & D ARM CALIBRATION PROCEDURE
on page 10 - 11.
13. See the WEIGHT SENSOR CALIBRATION PRO-
CEDURE on page 9 - 10.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 27

 Direct Drive
*Motor Service Kit Instructions Part No. Description
8112945 Motor Replacement Kit
Hennessy now has available a service motor kit for
the 950/1025/1050/1055 Contactor & Solid State
Balancers which will allow everyone to use one part
number when ordering a motor. The kit will be a com- CAUTION
plete motor assembly, hardware bag, & wiring instruc- Remember to unplug the balancer before
tions. The hardware bag will contain wires, wire nuts, servicing.
spade connectors & a green phoenix connector. It will
require a crimping tool to crimp the spade connectors
to motor wires as needed for contactor style units.

*950 Pro Racer

Hennessy is proud to announce the 950 Pro Racer
Balancer. This machine is a 950 contactor style machine
CAUTION
The PCB part number is Different due to the
with new software for racing wheels and utilizes a 1001
software (8112850). The CPU chip may be
balancer motor. The 950/1050 Service Manual and
changed with a standard 950/1050 PCB
Calibrating instructions should be used when servicing
(8110946/8111886) in the event you have a
this unit along with the attached wiring diagram and
machine down condition for a PCB problem.
parts list.
Note: The piezo spring tension should be
adjusted to the same spec as the 950/1050
which is 2". All other troubleshooting proce-
dures remain the same as the 950/1050.

28 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*950 Pro Racer Wiring Diagram

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 29

 Direct Drive
*950 Wiring Diagram (Contactor Style)

30 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*1050 Wiring Diagram (Contactor Style)

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 31

 Direct Drive
*Solid State Wiring Diagrams &
Troubleshooting Guides CAUTION
*For units produced after 1/1/98. Please use caution when installing the hood
A new Solid State Motor Controller replaced the bar into the machine being careful not to
mechanical contactor and a second hood (Interlock) damage the switch lever with the actuating
switch was added. rod. Note - a piece of Styrofoam has been
In January of 2000 the magnetic switches were inserted as packing material to insure ade-
changed to mechanical switches, refer to the appropri- quate room for inserting the actuator rod.
ate wiring diagram for troubleshooting and repair. Please refer to the attached Hood
Installation Instructions and wiring dia-
*Mechanical Hood Switches grams. The operators manuals have been
Hennessy has introduced a new style hood switch on updated with current parts lists and addi-
the 850and 950/1025/1050/1055 solid state model bal- tional copies can be ordered through our
ancers. Beginning with Serial # 0001308154. These are order entry department.
mechanical rather than magnetic switches and require
a different activating procedure. As a result the hood Old Part New Part
Number Number
bracket on the balancer and hood bar have been 8305050 8144114 Switch
redesigned. These parts are not reverse compatible 8110014 8112843 Hood Bar
therefore you will still need to carry the previous mag- 8112731 Actuator Rod
netic switches & magnets (8305050 & 8112414) in your 924724 Serrated Nut
service inventory. 8111812 850S Operator Manual
8111868 950 thru 1055 Operators
Manual

32 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*Mechanical Hood Switch Diagram

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 33

 Direct Drive
*1050 Wiring Diagram (Motor Controller Style/Magnetic Switches)

34 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

Direct Drive

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 35

 Direct Drive
*1050 Wiring Diagram (Motor Controller Style/Mechanical Switches)

36 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

Direct Drive

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 37

 Direct Drive
*Motor Controller Test Box #8112708

Forward and In-Line "Control Signal"

Reverse "Control" Detection
Output

CONTROL SIGNAL DETECT

In-Line Signal
FORWARD SPIN STOP Dectector
Forward Indicator LEDs
Control
REVERSE

Reverse Power
Control ON Indicator

MOTOR OFF Power

CONTROLLER Switch
HENNESSY INDUSTRIES,INC.

Solid State
Solid State CPU
Motor Controller Solid State
Motor Controller Control Out
PCB Motor Controller
PCB PCB

CONTROL SIGNAL DETECT

CONTROL SIGNAL DETECT CONTROL SIGNAL DETECT

FORWARD SPIN STOP

FORWARD SPIN STOP FORWARD SPIN STOP

REVERSE
REVERSE REVERSE
ON
ON ON

MOTOR OFF
CONTROLLER MOTOR OFF MOTOR OFF
HENNESSY INDUSTRIES,INC. CONTROLLER CONTROLLER
HENNESSY INDUSTRIES,INC. HENNESSY INDUSTRIES,INC.

Mode 1 Mode 2 Mode 3

Forward and Reverse A Loop-back plug The Diagnostic Tool
buttons are used to is connected from is connected in-line
control signals the Control Output with the control cable
to the Solid State back to the Signal from the CPU Motor Control
Motor Control PCB Detection input to output to give
monitor the Control an indication of the
Signal output of the presence of the
Diagostic Tool while Control signal
manually applying the
control signal.

38 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*Display Does Not Light (Solid State Motor Controller Model)

Is the power switch set No Turn the power

to the ON position? switch ON.
Yes

Is the proper voltage and ground

present at the receptacle? See No
Have the voltage supply to
Checking Procedure. the machine corrected.

Yes

Reset the tripped breaker. If the

Has one of the 2A breakers on Yes
breaker trips again, replace the PCB.
the power panel tripped?
See Replacement Procedure.
No

Disconnect the 2 RED wires

Is there between 200 & 230VAC
Yes from the circuit breakers. Is No Replace the transformer. See
between the terminals marked 0V
there 24VAC between these 2 Replacement Procedure.
& 230V (1 & 3) on the
RED wires? Reconnect wires.
transformer?
Yes

No Checks If either of the breakers are open,

Turn the power off and unplug the
Bad try resetting and rechecking. If
machine. Check the continuity of
the breaker remains open & does
the two (2) 2A circuit breakers.
not trip, replace the breaker.
Checks Good
Breaker
Trips
Connect the machine to a power
source and turn the power switch Replace the PCB. See
Yes
ON. Is there 20VAC between Replacement Procedure.
pins 1 & 2 on the connector on
the right side of the PCB?
No
Checks
Good
Turn the power off and unplug the
machine. Check the continuity of Checks
the RED wires from the trans- Bad Repair or replace the
former pins 1 & 2 on the connec- defective wire or connection.
tor on the right side of the PCB.
Checks Bad
Turn the power off and unplug
the machine. Turn the power Checks Check the continuity of the wire
Good from the terminal marked 0V on
Is there 220VAC between switch to the ON position. Check
Yes the transformer to terminal 1 on
terminals 1 & 3 on the the continuity of the wire from the
power supply connector 230V terminal on the transformer the Motor Controller.
on the Motor Controller to terminal 3 of the Motor Checks
Bad Checks
pcb? Controller. Check the continuity of
Good
the power switch.
No Checks Bad

Yes Replace the Motor Controller

Replace the power switch. See
Is there 220VAC between pcb
Replacement Procedure.
terminals 1 & 2 on the T1
terminal ot the MC pcb?
No Check the continuity of the Checks Repair or replace
power cord from the terminals to Bad
the defective wire
the appropriate connection on
or connection.
AC plug.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 39

 Direct Drive
*Balancer Does Not Cycle (Solid State Motor Controller Model)
To use the following chart you will need a tire and wheel assembly mounted on the balancer, the hood closed,
and the proper A, W, and D dimensions entered. If you are unable to manually enter the proper wheel dimensions,
replace the touch panel.

Tur n balancer on.

Press spin
(balancer must
display info. to
proceed.)
Replace MC PCB. Ye s

C h e ck
Connect continunity of
Does motor buzz MC test box to interlock switch with
No No
or try to turn? MC PCB. Does hood down at p7.
motor spin? Is there
continunity?

Ye s Ye s No
Troubleshoot AC.
Repair/replace the
No Plug RJ11 hood switch or wiring
Is AC correct to T1 from CPU PCB into
No
of MC PCB? MC test box. Does
motor spin?

To make this check, use the

MC test box to activate the
Ye s Ye s
spin voltage during test.
Replace control cable.

Is AC correct on Do location
Troubleshoot
No Motor connection of L E D s m ove w h e n Ye s
Encoder system
MC PCB? wheel is rotated?

Ye s No

Check wiring to motor. Replace Main PCB.

Replace motor.

Check wiring
connection on P4.
Check/replace MC = M otor Controller.
capacitors.
Replace MC PCB. MC Test Box # 8112078

40 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*Balancer Does Not Brake (Solid State Motor Controller Model)

Balancer must spin

and displaying
infor mation to
proceed.

Does an error Does wheel

Ye s
message appear? attempt to stop?

Ye s

Cross reference
error message to
No table and No
troubleshoot from
the given location.

Do
readings appear Use MC test box, Test Comm. cable.
on display after Ye s will motor spin & No Replace Motor
wheel has stop? Controller
stop?

Ye s
MC = M otor Controller.

Test Comm. Cable. MC Test Box # 8112078

No Replace the Main
P C B.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 41

 Direct Drive
PCB Checklist Addendum
Hennessy has noticed a considerable increase in the
amount of NAD’s (No Apparent Defect) for the
950/1050 PCB’s (8111886). Most NAD’s are in the
“Chasing Weights” category. The next reason for PCB
return is due to the Motor Controllers failing. Some of
the PCB’s returned tested OK. Below is a quick test to
help determine if the PCB is defective. This test does
not pertain to any other PCB’s.
Remove PCB from Touch Panel.
Figure 1 - PCB 8111886
Tools Needed: Digital Multimeter with leads.
Diode Test
Using a multimeter, set the function indicator to the
diode function and check Diodes D9 (Rev D boards) and
D10/D11 (Rev E and above) to see if they are shorted.
Perform the following procedure for each diode. Pin 1 Pin 14
1. Connect the multimeter’s black lead to the left side
of the diode and the red end on the right. If the diode
is good, you will hear a short beep and the reading on Pin 8
Pin 7
the meter should be between .5 and .7, (if you’re using
an Ohmmeter the reading will be about 5 Meg Ohms
(Ω)). If the diode is bad, you will hear a continuous tone
and the multimeter reading will be 0 (same for ohm Figure 2 - Pin Configuration
scale) unless it’s open - no tone reading.
2. Next, switch the multimeter leads. Connect the Note:
black lead to the right side of the diode and the red lead
• Pin 7 is GND on the IC’s. (You will hear a continu-
to the left. In this configuration, your multimeter should
ous beep).
read an open (OL), if the diode is good (same for
Ohmmeter). The multimeter display should look the • Pin 14 is VCC on the IC's. (You will hear a short beep
same as it does when the leads aren’t connected to or read .5 - .7 on the Diode Scale.) This is OK. Only if
anything. If the diode does not read open, in this step, you measure 0 Ohms or hear a continuous beep is the
then it is bad. IC bad.
IC Test • IC U19, pins 7, 11, 14, and 13 are the only pins
Use a multimeter to check for ground shorts on IC’s where you should read 0 Ohms or hear a continuous
(U8, U12, and U19). beep.
1. Set the multimeter up for continuity (or diode) If any other pins (not listed) are shorted to ground,
checking. read 0 Ohms, or you hear a continuous beep on the
IC’s listed above, THE PCB IS DEFECTIVE. DO NOT
2. Connect the common lead of the multimeter to a INSTALL PCB BACK INTO THE BALANCER.
ground point on the PCB. A good place is the negative
end of capacitor C15 or C16 (see fig.1). If the IC’s and the diodes check out OK, but the PCB
does not display any lights, THE PCB IS DEFECTIVE.
3. Take the multimeter positive lead and check the DO NOT INSTALL PCB BACK INTO THE BALANCER.
pins on the IC’s above.
Rev 1

42 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055

 Direct Drive
*Glossary Of Terms
Accuracy Check - Also referred to as Plane
Separation. When a weight is placed on one side
(plane) of a wheel the opposite side (plane) should not
change.
Balancer Calibration - Also know as Weight Sensor
Calibration. This process uses a specified size wheel
and a 4 oz. weight to make sure the balancer giving the
correct reading.
Distance Gauge Tape Placement - Also know as
Optimizing A. If there is a problem with the accuracy
check this is the procedure to correct the problem.
Hub Centric Wheel - A wheel that is centered to the
axle by the center hole in the wheel.
Lug Centric Wheel - A wheel that is centered to the
axle by the lug bolts.
Rotational Check - This is a procedure to verify if
there is a problem in the balancer or the mounting of
the wheel. This should be done with a Hub Centric
wheel.

Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 43

9111123 03 11/05 © Copyright 1992 Hennessy Industries and COATS All Rights Reserved Printed in USA