Precor c944 User manual

C944 Treadmill
Page 1
C944 Treadmill
Warning: This service manual is for use by Precor trained service providers only.
IfyouarenotaPrecorTrainedServicer,youmustnotattempttoserviceanyPrecorProduct;
Call your dealer for service.
This document contains information required to perform the majority of troubleshooting, and
replacement procedures required to repair and maintain this product.
This document contains general product information, software diagnostic procedures (when
available), preventative maintenance procedures, inspection and adjustment procedures,
troubleshooting procedures, replacement procedures and electrical block and wiring diagrams.
To move directly to a procedure, click the appropriate procedure in the bookmark section to the
left of this page. You may “drag” the separator bar between this page and the bookmark section
to change the size of the page being viewed.
© 2003 Precor Incorporated
Unauthorized Reproduction and Distribution Prohibited By Law

C944 Treadmill
Page 2
Section One - Things you Should Know
About This Appendix
Section One, Things You Should Know. This section includes technical specifications. Read
this section, as well as the C944 Treadmill Owner’s Manual, before you perform the maintenance
procedures in this manual.
Section Two, Software Features. Precor’s C944 Treadmill is programmed with several
diagnostic and setup features. This section contains the procedures you need to access the
diagnostic features on this treadmill.
Section Three, Checking Treadmill Operation. This section provides you with a quick way of
checking treadmill operation. Check treadmill operation at the end of a maintenance procedure
and when it is necessary to ensure that the treadmill is operating properly.
Section Four, Inspection and Adjustment Procedures. Perform inspection procedures when
a trouble symptom points to a particular problem and after removing and replacing major
components. Many maintenance problems can be fixed by adjusting various treadmill
components. This section also provides you with the step-by-step procedures required to make
these adjustments.
Section Five, Troubleshooting Procedures. The diagnostic and troubleshooting procedures
contained in this section should be performed when it is necessary to isolate a problem to a
particular component.
Section Six, Replacement Procedures. When a treadmill component must be replaced, go to
this section and follow the step-by-step procedures required to remove and replace the
component.
Section Seven, Technical Diagrams and Parts Lists. This section includes wiring diagrams,
and block diagrams for SCR and PWM C944 Treadmills.
General Information
For the latest exploded view, part number and part pricing information, visit the Precor dealer
website at “www.precor.com/Dealer”.

C944 Treadmill
Page 3
Technical Specifications
Physical Specifications
Length: 76 inches (193 cm)
Width: Handrails 31.5 inches (80 cm)
Base 28.5 inches (72 cm)
Height: 44 inches (112 cm)
Running surface: 53 inches by 18 inches (135 cm by 46 cm)
Motor: 2 hp continuous duty DC (120 Vac and 240 Vac
models)
Speed: 0.5 to 12 mph (0.8 to 19 kph)
10 mph is equivalent to a 6 minute mile
Incline: -2% to +12% grade
Power: 50/60 Hz 120 Vac
50/60 Hz 240 Vac
Weight: 276 lbs (119 kg)
Shipping Weight: 326 lbs (147 kg)

C944 Treadmill
Page 4
Procedure 2.1 - Accessing the Diagnostic Software
The C944 Treadmill's diagnostic software consists of the following modes:
• Display Test
• Manual Lift Adjust
• Troubleshoot Lift
• Software Version
• Power Bits
• Keypad Test
Procedure
1. Plug the power cord into the wall outlet, then turn on the treadmill with the circuit breaker.
2. With the PRECOR C944 banner scrolling, press the SPEED ▲, SPEED ▼and INCLINE ▲
keys simultaneously or keys RESET,5,1,7,6.5.7.6,1, sequentially on units with standard
access codes (see Diagram 2.1).
3. Watch the electronic display as the LED test progresses. This test is programmed to display
the following LED illumination sequence.
a Every LED on the left display window illuminates simultaneously
b The lower row of the display window cycles from red to yellow to green.
c Diagonal lines of illuminated LEDs sweep across the left display window.
d The right display windows illuminate, then decrement from 8.8.8.8 to 0.0.0.0.
e The function LEDs illuminate simultaneously and then extinguish.
f Each function LED illuminates separately and then extinguishes.
4. If you do not observe the LED illumination sequences described in Step 3...
THEN... OTHERWISE...
Replace the upper PCA as described The LED passed successfully;
in Procedure 5.2 of the Commercial continue with the next step.
Treadmill Service Manual.

C944 Treadmill
Page 5
Diagram 2.1. C944 Treadmill Display
5. With the ADJUST LIFT banner scrolling, press the INCLINE keys. The running deck will
incline when the INCLINE ▲ key is pressed and decline as the INCLINE ▼key is pressed.
The running deck will stop moving when the key is released. After the INCLINE keys are
pressed, the message, PRESS ENTER WHEN FINISHED will scroll by.
Note:
The following diagnostic test automatically searches for the upper and lower limit switches and
the zero sense switch. It also detects a non-functional (non-moving) lift.
6. Watch the electronic console. If the three limit switches are adjusted correctly, the following
series of messages is displayed on the electronic console:
GOING TO TWELVE PERCENT
AT TWELVE PERCENT
GOING TO UPPER LIMIT
GOING TO NEG TWO PERCENT
AT NEGATIVE TWO PERCENT
GOING TO LOWER LIMIT
GOING TO ZERO
7. If all of the messages listed in Step 6 are displayed on the electronic console...

C944 Treadmill
Page 6
THEN... OTHERWISE...
The treadmill lift switches are Press RESET to return to the PRESS
calibrated correctly, press ENTER ENTER FOR PROGRAMS prompt,
to continue. then calibrate the lift systems
described in Procedure 4.1.
Note:
Software revision changes can only be made by replacing the currently installed PROM. The
revision of the software does not change by resetting the system. Some software updates may
require the user to perform a system reset.
Software numbers are invaluable for tracking and identifying problems and keeping abreast of
changes to the operation and features of the product.
8. The message VERSION scrolls across the display and will continue to do so while you hold
any key down. When the key is released you will see the software version number displayed
in the middle right seven-segment display. Press ENTER to exit this mode.
Note:
The following mode allows manual control of the motor speed while displaying the power bits. It
is useful in determining if the system is having difficulties running the motor and belt.
9. The message POWER BITS scrolls across the display once. Two numbers appear in the
right upper and right middle seven-segment displays. The upper number is the power bits
and the lower number is the requested speed in miles-per-hour (or kilometers-per-hour).
Press the SPEED ▲key to start the motor. The SPEED ▲, SPEED ▼, STOP and ENTER
keys are active in this mode.
10. Press the SPEED keys while you watch the right display window. The power bits number
increments as the SPEED ▲key is pressed and decrements as the SPEED ▼key is
pressed.
11. Press either the STOP key or the ENTER key to stop the motor and exit this diagnostic.
Press the SPEED ▼key until zero MPH (or KPH) is attained if you wish to stop the motor but
not exit this diagnostic.
Note:
The keypad test is useful for troubleshooting stuck or non-operating keys on the keypad.

C944 Treadmill
Page 7
12. Press each key listed below. Verify that each single dot expands to four dots as the
appropriate key is pressed.
ENTER Expands the far left dot.
INCLINE ▼Expands the second dot from the left.
INCLINE ▲Expands the third dot from the left.
STOP/RESET Expands the center dot.
SPEED ▼Expands the third dot from the right.
SPEED ▲Expands the second dot from the right.
QUICK START/CHANGE Expands the far right dot.
13. If the left display window column illuminates appropriately as each key is pressed...
THEN... OTHERWISE...
The keypad test passed successfully; Troubleshoot the upper PCA and
continue with the next step. keypad as described in Procedure 5.1
of this appendix.
14. End the keypad test by pressing the INCLINE ▼and SPEED ▲keys simultaneously.

C944 Treadmill
Page 8
Procedure 2.2 - Displaying the Treadmill Odometer
This procedure displays total distance (in miles or kilometers) the treadmill has operated. The
odometer cannot be reset.
Note:
The odometers get updated at the end of the course. If a user shuts off the unit while in the
middle of a course, the odometer will not be updated and the user will have essentially lost the
mileage for that session. Pressing RESET displays the PRECOR C944 banner and accumulates
the mileage.
Procedure
1. Plug the power cord into the wall outlet, then turn on the treadmill with the circuit breaker.
2. With the PRECOR C944 banner scrolling, press the INCLINE ▲and SPEED ▲keys
simultaneously or keys RESET,6,5, sequentially on units with standard access codes.
Note:
The right display window displays total miles or kilometers on the treadmill (see
Diagram 2.2). The top display window shows the most significant bits of the number; the lower
display window shows the least significant bits of the number. The number displayed is
102,187,723 (in miles or kilometers).
3. Press ENTER to return to the PRECOR C944 banner.
Diagram 2.2. - Odometer Display
0001
0218
7723

C944 Treadmill
Page 9
Procedure 2.3 - Changing Club Settings
This procedure allows you to change the following club settings:
• English Standard /Metric Units
Selecting United States standard units causes data to be displayed in feet, miles and
pounds. Data is displayed in meters, kilograms and kilometers if metric units are selected.
• Maximum Speed
This selection is used to artificially limit the maximum speed the treadmill can attain when a
user is working out.The C944 Treadmill can attain an absolute maximum speed of 12.0
MPH (20.0 KPH) for PWM units and 10.0 MPH (16.0 KPH) for SCR units. This speed selec-
tion mode cannot exceed these speeds, but rather speeds may be selected that are lower
than these maximums.
• Maximum Workout Time
This club selection is used to limit the maximum workout time the treadmill may be used
during a workout. The time may range from a minimum of 10 minutes to an absolute maxi-
mum of 240 minutes. The default from the factory is 60 minutes.
Procedure
1. Plug the power cord into the wall outlet, then turn on the treadmill with the circuit breaker.
2. If you wish to verify the measurement standard the treadmill is currently using continue with
the next step. If you wish to change the measurement standard the treadmill is using, skip to
Step 5.
Checking the Measurement Standard
3. Press ENTER until the WEIGHT indicator light appears.
4. Watch the number displayed in the left display window while you press the SPEED ▲key
five or six times.
Note:
If the treadmill is using United States standard units, the numbers in the left display window are
repeatable multiples of 5 (such as 160, 165, 170, 175, etc.). Otherwise, the treadmill is using
metric units.

C944 Treadmill
Page 10
Changing the Measurement Standard
5. With the PRECOR C944 banner scrolling, press the SPEED ▲and QUICK START/
CHANGE keys simultaneously or keys RESET,5,6,5,1,5,6,5, sequentially on units with
standard access codes. A message indicating the last selected units (either U. S.
STANDARD UNITS or METRIC UNITS) scrolls across the display.
6. Use the SPEED or INCLINE keys to select the alternate measurement standard.
Note:
Holding the INCLINE UP and CHANGE keys at the banner may cause the last selected units to
change if the INCLINE UP key is released before the CHANGE key.
Selecting Maximum Workout Speed
For PWM treadmills, the maximum workout speed limit is between either 1 and 12 MPH or 1 and
20 KPH. Maximum workout speed limits for SCR C944 treadmills range between 1 and 10 MPH
or 1 and 16 KPH.
7. With the last currently selected maximum speed displayed on the L.E.D. matrix, use the
SPEED or INCLINE keys to designate a workout speed limit. Press ENTER when the
desired speed appears.
Selecting Maximum Workout Time
8. With the last currently selected maximum time displayed on the L.E.D. matrix, use the
SPEED or INCLINE keys to designate a workout time limit. Press ENTER when the desired
time appears.

C944 Treadmill
Page 11
Procedure 2.4 - Documenting Software Problems
When a problem is found with either the software or upper or lower PCA’s, record the information
listed below. If you isolated the problem to either the PROM, upper PCA, or lower PCA, include
the information you recorded with the malfunctioning PROM or PCA when you ship it to Precor.
When a problem occurs, record the following information:
• Model and serial number
• Software version number
Note
Determine the version number of the PROM as described in Procedure 2.1 (or by looking at the
label on the PROM).
• User and program number running when the problem occurred
• A description of:
a What happened or failed to happen.
b The action taken by the user just before the problem occurred.
c Problem-related information (such as how far into the program the problem occurred,
the work level being used when the problem occurred, etc.).
• The frequency of occurrence.

C944 Treadmill
Page 12
Section Three - Checking Treadmill Operation
This section provides you with a quick method of checking treadmill operation. Check treadmill
operation at the end of a maintenance procedure and when it is necessary to ensure that the
treadmill is operating properly.
Procedure
4. Plug the power cord into the wall outlet, then turn on the treadmill with the circuit breaker.
5. Place the treadmill in Manual Mode. Adjust the speed of the running belt to 2–3 mph
Operate the treadmill for at least 5 minutes.
a. Concentrate on the feel of the running belt and the sound of the drive motor and rollers.
Be on the alert for unusual noises, smells, or vibrations.
b. On SCR units, measure and log the AC input current under loaded and unloaded con-
ditions. On PWM units, log the power bits under loaded and unloaded conditions.
c. Observe the LEDs on the electronic console. Make sure that each LED lights as the in-
formation corresponding to that LED is displayed on the electronic console.
3. Press the STOP key. When the treadmill comes to a stop, view the electronic console as the
treadmill scans time, speed, distance and percent of lift.
4. Press the INCLINE ▲key while viewing the electronic console. Confirm that the running
bed inclines and the incline display increments to twelve percent as the INCLINE ▲key is
pressed.
5. Press the INCLINE ▼key while viewing the electronic console. Confirm that the running bed
returns to a level position and the incline display decrements to minus two percent as the
INCLINE ▼key is pressed.
Turn off the treadmill with the circuit breaker, then unplug the treadmill from the wall outlet.

C944 Treadmill
Page 13
Procedure 4.1 - Calibrating the Lift Limit Switches
WARNING
Always turn off the circuit breaker and unplug the treadmill before you remove the treadmill hood.
1. If the treadmill is not already at zero percent incline, press any key when the CALIBRATE
LIFT PRESS ANY KEY prompt is displayed.
2. Using the ruler, measure the distance between the floor and the top of the front and back
ends of the side rail (see Diagram 4.1).
Note:
The distance between the floor and the top of the front end of the side rail should be 9 inches.
3. If the distances recorded in the previous step are equal to within 1/4" . . .
THEN . . . OTHERWISE . . .
Skip to Step 17. Continue with the next step.
4. With the PRECOR C944 banner scrolling, press the SPEED ▲, SPEED ▼and INCLINE ▲
keys simultaneously or keys 4,5,1,7,6.5.7.6,1, sequentially on units with standard access
codes.
5. Press ENTER when the display test starts.

C944 Treadmill
Page 14
Diagram 4.1 - Measuring the Side Rail
6. With the ADJUST LIFT prompt displayed, press either the INCLINE ▲ or ▼ INCLINE
key to move the lift. The message PRESS ENTER WHEN FINISHED is displayed on the
electronic console.
7. If the distance measured at the front of the side rail is larger than the distance measured at
the back of the side rail . . .
THEN . . . OTHERWISE . . .
Press the INCLINE ▼ key until Press the INCLINE ▲ key until the
the front and back treadmill front and back treadmill measurements
measurements are equal; then are equal; then press RESET.
press RESET.
8. Turn off the treadmill with the circuit breaker, then unplug the power cord from the wall
outlet.
WARNING
Before continuing with this procedure, review the Warning and Caution statements listed in
Section One of the Commercial Treadmill Service Manual.
9. Remove the hood.
10. Check the position of the zero sense switch in relation to the switch actuator (see
Diagram 4.2)
11. If the widest point of the switch actuator is lined up with the center of the wheel on the zero

C944 Treadmill
Page 15
sense switch . . .
THEN . . . OTHERWISE . . .
The zero sense switch is calibrated The switch bracket must be adjusted;
correctly; skip to Step 16. continue with the next step.
WARNING
When power is applied to the treadmill, the wires connected to the upper and lower limit switches
carry 110 volts (or 220 volts if you are servicing a 220-volt treadmill). Turn off the treadmill and
unplug the power cord from the wall outlet before you perform the following steps.
12. Loosen the socket head bolts and washers that secure the switch bracket to the lift platform
(see Diagram 4.2).

C944 Treadmill
Page 16
Diagram 4.2 - Limit Switch Bracket
Note:
The zero sense switch can be actuated if the center of the wheel is slightly above or slightly
below the widest point of the switch actuator. However, for best results, adjust the position of the
zero sense switch as described in the following step.
Lower Limit
Switch
Actuator
Zero Sense
Switch
Upper Limit
Switch

C944 Treadmill
Page 17
13. If the center of the wheel on the zero sense switch is above the widest point of the switch
actuator . . .
THEN . . . OTHERWISE . . .
Move the switch bracket down until Move the switch bracket up until the
the widest part of the actuator is widest part of the actuator is centered
centered on the wheel on the zero on the wheel on the zero sense switch;
sense switch; then continue with then continue with the next step.
the next step.
14. Tighten the socket head bolts and washers that secure the switch bracket to the lift platform
(see Diagram 4.2).
15. Replace the hood.
16. Check the operation of the treadmill as described in Section Three of this appendix.
IMPORTANT
If the electronic console displays the diagnostic message LIFT ERROR PRESS STOP when you
incline and decline the running bed to its maximum limits, repeat this procedure.
If readjusting the position of the switch actuator does not fix the problem, refer to Procedure 2.4
in this appendix.

C944 Treadmill
Page 18
Procedure 5.1 - Troubleshooting the Keypad and Upper PCA
If the function keys on the electronic console are unresponsive, the problem may be either the
upper PCA or keypad. This troubleshooting procedure gives you the information you need to
determine which of these components is malfunctioning.
Procedure
1. Set the circuit breaker in the “off” position.
WARNING
Before continuing with this procedure, review the Warning and Caution statements listed in
Section One of the Residential Treadmill Service Manual.
2. Remove the screws that secure the upper display assembly to the upper handrail. Carefully,
pull some excess interconnect cable out from the targa upright. Rotate the display housing,
so that the rear of the upper PCA is facing upward, and set the display housing on the upper
handrail.
3. Attach the wrist strap to your arm, then connect the ground lead of the wrist strap to the
treadmill frame.Set the voltmeter to a range that will conveniently read +6 Vdc.
Diagram 5.1 - Upper PCA Component Layout
4. Set the voltmeter to a range that will conveniently read +6 Vdc.
5. Set the circuit breaker in the “on” position.
6. Use a DVM, set for DC volts, and read between pin 6 of J3 and the each of the pins in Table
5.1 (no keys pressed) and Table 5.2 (with the appropriate key pressed)...
U3
J5
U13
J4
RN5
RN4
2
1
26
25
J2
J1

C944 Treadmill
Page 19
Table 5.1 - Voltage Test Points (Function Keys Not Pressed)
Place the positive lead of the The voltmeter should read...
voltmeter on...
Pin 3 of J3 5 Vdc ± 500 mVdc
Pin 4 of J3 5 Vdc ± 500 mVdc
Pin 5 of J3 5 Vdc ± 500 mVdc
Pin 7 of J3 5 Vdc ± 500 mVdc
Pin 8 of J3 5 Vdc ± 500 mVdc
Pin 9 of J3 5 Vdc ± 500 mVdc
Pin 10 of J3 5 Vdc ± 500 mVdc
Table 5.2 - Voltage Test Points (Function Keys Pressed)
Place the positive At the display The voltmeter should
voltmeter lead on... enclosure, press... read between...
Pin 3 of J3 ENTER 0 Vdc and 500 mVdc
Pin 4 of J3 INCLINE DOWN 0 Vdc and 500 mVdc
Pin 5 of J3 INCLINE UP 0 Vdc and 500 mVdc
Pin 7 of J3 STOP 0 Vdc and 500 mVdc
Pin 8 of J3 SPEED DOWN 0 Vdc and 500 mVdc
Pin 9 of J3 SPEED UP 0 Vdc and 500 mVdc
Pin 10 of J3 QUICK START 0 Vdc and 500 mVdc
7. If the voltage readings match those listed in Tables 5.1 and 5.2 and one or more keys do not
function, replace the upper PCA.
8. If the voltage readings in Table 5.1 are incorrect, disconnect the keypad cable from the key
pad connector and repeat the voltage measuremnts in 5.1. If the voltage readings are now
correct, replace the display housing (keypad). If the voltage readings are still incorrect,
replace the upper PCA.
9. If the voltage readings in Table 5.1 are correct and one or more voltage readings in Table
5.2 are incorrect, replace the display housing (keypad).
10. Set the circuit breaker in the “off” position.
11. If necessary, carefully re-connect the keypad cable to the keypad connector.
12. Remove the ground lead of the wrist strap from the treadmill frame, then remove the wrist
strap from your arm.
13. Position the display enclosure on the display plate. Install the screws that secure the display
enclosure to the display plate.
14. Check the operation of the treadmill as described in Section Three of this appendix.

C944 Treadmill
Page 20
Procedure 5.2 - Troubleshooting the Lift System
Lift System Description:
The lift system on these units consists of an AC line voltage driven lift motor (120 Vac or 240
Vac), a hall effect rotation sensor and three position location switches. The lift system orients
itself by locating the zero sense switch when the treadmill is powered up. When the zero sense
switch is activated the system recognizes that physical position as 0% incline. If the zero sense
switch is activated when the treadmill is powered up, the system proceeds directly into the
normal program mode. If the zero sense switch is not activated when the treadmill is powered up,
the system performs a self calibration procedure. The purpose of the self calibration procedure is
to locate the zero sense switch (0% incline). The user will be prompted to press any key to
commence the lift calibration. The treadmill will go up 4%, because the lowest the treadmill could
have been at power up is -3%. If the treadmill does not locate the zero sense switch by going up
4%, it will stop and then go down until it activates the zero sense switch. The system will then
proceed to the normal program mode. Once the 0% lift position has been located, the system
tracks any subsequent lift operations by counting motor revolutions. A hall effect sensor is
mounted on a bracket that is next to a hub that is attached to the lift motor shaft. As the lift motors
operates, a magnet mounted in the hub, passes the hall effect sensor once per motor revolution.
The hall effect sensor send one pulse to the lift control system per revolution. The system knows
how far the lift travels per revolution and by counting revolutions (hall effect sensor pulses),
knows the current lift position. The other two position switches (upper and lower limit) do not
come into play during normal operation. If either switch is activated it means that the lift has
moved beyond it’s normal range of motion. When either limit switch is activated, power is
removed from the lift motor. Removing power from the lift motor, protects the lift system from
physical damage.
Note:
All resistance measurements must be performed with power removed from the treadmill.
Performing resistance measurements with voltage applied may damage your ohmmeter.
Procedure
1. If the lift motor operates but creates a lift error (error 40, 41 or 43) go to step 8. If the lift
motor will not move continue with step 2.
2. Put the treadmill in a condition in which the lift motor is ready to be operated (for example,
quick start into the manual program). Using an AC voltmeter, monitor the voltage across the
lift capacitor and press one of the incline keys. Approximately 1.4 times the AC input voltage
should appear on the lift capacitor when an incline key is pressed. Approximately 170 Vac
on a 120 Vac unit or approximately 340 Vac on a 240 Vac unit. The actual lift capacitor
voltage will vary with the AC input voltage. If AC line voltage or 1.4 times line voltage is on
the lift capacitor go to step 6. If no AC voltage is on the lift capacitor, continue with step 3.