Precor C844 User manual

C844 Upright Cycle
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C844 Bicycle
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

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Section One - Things You Should Know
Right, Left, Front, and Back Conventions
In this manual, right, left, front, and back are from the perspective of a user sitting on the C844,
facing the display enclosure.
Warning and Caution Statements and General Safety Guidelines
Warning statements indicate a particularly dangerous activity. Warning statements you will find in
this manual include:
• To remove power from the C844, the power cord must be disconnected from the wall outlet.
Always ensure that the C844 is unplugged from the wall outlet when you inspect or adjust the
C844, or when you isolate, remove, or replace a C844 component.
• Removing the covers exposes high voltage components and potentially dangerous
machinery. Exercise extreme caution when you perform maintenance procedures with the
hood removed.
• During service operations you will be very close to moving machinery and high voltage
components. When you perform maintenance procedures with the covers removed, remove
jewelry (especially from ears and neck), tie up long hair, remove neck ties, and do not wear
loose clothing.
• Exercise caution when touching any wire or electrical component during C844 operation.
• The flywheel is very heavy. Be prepared for the weight of the flywheel when it comes off of
the flywheel shaft.
Caution statements are intended to prevent damage to the C844 as a result of the current
activity. Caution statements included in this manual are listed below:
• Notice the orientation notch on the PROM (U3). These components must be positioned with
the same notch orientation.
• When it is necessary to lift the C844, ensure that the C844 has adequate support. Do not lift
the C844 by the front cross-member.
Safety guidelines you should know and follow include:
• Read the owner’s manual and follow all operating instructions.
• Visually check the C844 before beginning service or maintenance operations. If it is not
completely assembled or is damaged in any way, exercise extreme caution while operating

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and checking the C844.
• When operating the C844, do not wear loose clothing. Do not wear shoes with heels or
leather soles. Check the soles of your shoes and remove any embedded stones. Tie long hair
back.
• Do not rock the unit. Do not stand or climb on the handlebars, display enclosure, or cover.
• Do not set anything on the handlebars, display enclosure, or cover. Never place liquids on
any part of the C844.
• To prevent electrical shock, keep all electrical components, such as the power cord and
circuit breaker away from water and other liquids.
• Do not use accessory attachments that are not recommended by the manufacturer, such
attachments might cause injuries.
General Information
For the latest exploded view, part number and part pricing information, visit the Precor dealer
website at “www.precor.com/Dealer.

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Required Tools and Equipment
The following is a summary of the tools and equipment that may be required when you service a
Precor C844 Upright Cycle.
Tools
Phillip and flat-head screwdrivers
Standard and metric allen wrench set
Open-end wrench set
Socket wrench set
Chip puller
Rubber mallet
Snap ring pliers
Torque wrench
Equipment
Anti-static kit
Digital multimeter
Supplies
Cable ties

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Procedure 2.1 - Performing C844 Cycle Diagnostics
This procedure tests or displays the following:
• Display Array
• Seven Segment Displays
• Baseline Resistance
• Software Revision Number
• Heart Rate Diagnostic
• Power Bits
• Keypad Test
1. Plug the power cord into the wall outlet, then turn on the cycle with the ON/OFF switch.
2. With the PRECOR C844 banner scrolling, press the STOP, WORK LEVEL UP and WORK
LEVEL DOWN keys simultaneously.
3. Verify that the entire left display window illuminates, then two diagonal lines sweep across
the display.
4. 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. Horizontal, vertical, and diagonal lines of illuminated LED’s sweep across the left display
window;
c. The right display windows illuminate, then decrement from 8.8.8.8 to 0.0.0.0;
d. The function LED’s illuminate simultaneously and then extinguish; and
e. Each function LED illuminates separately and then extinguishes.
5. If you do not observe the LED illumination sequence described in the previous steps . . .
THEN . . . OTHERWISE . . .
Replace the upper PCA as described Continue with the next step.
in Procedure 7.1.

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6. Make a note of the Baseline Resistance numbers displayed on the electronic console.
Individually press the WORK LEVEL keys and verify that the Baseline Resistance numbers
change as the WORK LEVEL keys are pressed.
7. The software version number is displayed on the electronic console. Press ENTER, then
release.
8. HArt is displayed in the right display window. Put on the heart rate monitor.
9. While using the Heart Rate Transmitter, verify that the HEART RATE indicator blinks in time
with your heart beat and the heart rate information displayed is correct . . .
THEN . . . OTHERWISE . . .
Diagnostic software HArt mode checks Refer to the Smart Rate System
correctly; continue with the next step. Service and Maintenance Manual.
10. Press ENTER, then release. The power bits is displayed on the electronic console. Press
ENTER, then release.

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Note: Seven dots are displayed in the center of the left window.
As you press each key listed in Step 11, the column of the left display window corresponding to
the key pressed should illuminate. When you release each key, the column of light should be
replaced by a single dot.
11. Press each key listed:
BLANK
ENTER
BLANK
STOP
WORK LEVEL UP
WORK LEVEL DOWN
12. If the appropriate sections of the left display window illuminated when the corresponding
keys were pressed . . .
THEN . . . OTHERWISE . . .
The keypad test passed successfully; Replace the upper PCA as described
continue with the next step. in Procedure 7.1.
13. Press ENTER and WORK LEVEL UP to return to the PRECOR C844 banner.

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Procedure 2.2 - Displaying the Odometer
This procedure displays total distance (in miles or kilometers).
1. Plug the power cord into the wall outlet, then turn on the bike with the circuit breaker.
2. With the PRECOR C844 banner scrolling, press the STOP and WORK LEVEL UP keys
simultaneously and hold them until the message CYCLE ODOMETER scrolls across the left
display window.
Note: The right display window displays total miles or kilometers on the cycle (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 twice to return to the User ID prompt.
Diagram 2-2. Odometer Reading For the C844 Cycle
0001
0218
7723

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Procedure 2.3 - Selecting Club Settings
This procedure allows the modification of the following settings:
• U. S. Standard/Metric
• Line Voltage Selection
• Get Max Workout Time
1. Plug the power cord into the wall outlet, then turn on the cycle with the ON/OFF switch.
2. With the PRECOR C844 banner scrolling, press the QUICKSTART and WORK LEVEL ▲
keys simultaneously. Across the left display window scrolls either the banner U. S.
Standard or the banner Metric.
3. If you wish to change the measurement standard . . .
THEN . . . OTHERWISE . . .
Use the UP or DOWN keys to toggle Continue with the next step.
to an alternate measurement standard;
then continue with the next step.
4. Press ENTER, then release. The line voltage currently selected is displayed on the left
display window.
5. If you wish to toggle to the alternate line voltage. . .
THEN . . . OTHERWISE . . .
Use the UP or DOWN keys to toggle Continue with the next step.
to the alternate line voltage; then
continue with the next step.
6. Press ENTER, then release. The maximum workout time is displayed on the left display
window.
7. If you wish to change the maximum workout time . . .

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THEN . . . OTHERWISE . . .
Use the UP or DOWN keys to select Continue with the next step.
the new maximum workout time;
then continue with the next step.
8. Press ENTER, then release to return to the C844 Cycle banner.

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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
Customer Support.
When a problem occurs, record the following information:
• Model and serial number
Note: The model serial number is located on the bottom of the lower crossbeam.
• Software version number
• Odometer reading
Note: Determine the version number of the PROM mounted on the upper PCA as described in
Procedure 2.1.
• 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

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Section Three - Preventive Maintenance
Preventive maintenance measures are either scheduled or unscheduled. Scheduled preventive
maintenance activities are included here so that you are aware of preventive measures
performed on a regular basis.
Regular Preventive Maintenance (Owner)
Cleanliness of the cycle and its operating environment will keep maintenance problems and
service calls to a minimum. Precor recommends performing the following preventive
maintenance schedule.
At the End of Each Day
• Wipe the pedals with a damp cloth.
Every Week
• Wipe the surface of the electronic console with a barely-damp sponge or soft cloth. Dry with
a clean towel.
CAUTION
Keep water away from electronic components to prevent shock.
On-Site Preventive Maintenance (Service Technician)
Perform the following preventive maintenance tasks each time you are called to service a C844:
• Check the LED’s mounted on the upper PCA and the function keys displayed on the elec-
tronic console by performing Procedure 2.1.
• Measure the gap between the flywheel and the magnets as described in
Procedure 5.1.
• Visually examine all wires and check connectors and wire connections. Secure connections
and replace wiring as necessary.
• When the covers are removed, visually inspect the lower ribbon cable and the part of the
upper ribbon cable that is not inside the column. If either ribbon cable is torn or damaged,
replace it as described in Procedure 7.7.

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Section Four - Checking Unit Operation
This section provides you with a quick method of checking cycle operation. Check the operation
of the C844 Cycle at the end of most maintenance procedures.
Procedure
1. Plug the power cord into the wall outlet, then turn on the bike with the circuit breaker.
2. If the display does not illuminate refer to procedures 6.3 0r 6.4.
3. When the PRESS ENTER FOR PROGRAMS prompt appears, press QUICK START.
4. Select Work Level 1 and press ENTER.
5. Operate the C844 for 4–5 minutes. As you operate the cycle, concentrate on the resistance
and operating sounds of the unit. Be on the alert for unusual rubbing, hitting, grinding or
squeaking noises.
6. Press the WORK LEVEL UP key until you reach Work Level 5. Operate the cycle for
another 2–3 minutes.
7. If the resistance of the cycle does not change or the operation of the cycle feels inconsistent
compared with Work Level 1 . . .
THEN . . . OTHERWISE . . .
Refer to procedures 6.5 and 6.6 Continue with the next step.
8. Press the WORK LEVEL UP key until you reach Work Level 10. Operate the cycle for
another 2–3 minutes.
9. If the resistance of the cycle does not change or the operation of the cycle feels inconsistent
with Work Levels 1 and 5 . . .
THEN . . . OTHERWISE . . .
Refer procedures 605 and 6.6 Continue with the next step.
10. Check the LED’s mounted on the upper PCA and the function keys displayed on the elec-
tronic console by performing Procedure 2.1.
11. If the keys do not respond appropriately, refer to procedure 6.2.

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Procedure 5.1 - Inspecting and Adjusting the Gap Between
the Magnets and Flywheel
WARNING
Always turn off the C844 with the ON/OFF switch and unplug the power cord from the wall
outlet before you service the cycle.
Procedure
1. Place the C844 Cycle on its front end. Remove the pan from the base of the cycle.
2. Loosen one of the magnet assemblies.
Note: Do not loosen the screws that secure the magnet assembly too much. Although you
must be able to move the magnet assembly along the adjustment slots, the assembly
must stay in place after it is moved.
3. Place a .050" feeler gauge between the flywheel and each of the magnet coils that make up
the magnet assembly.
4. Choose one. If the feeler gauge does not fit snugly . . .
THEN . . . OTHERWISE . . .
Continue with the next step. Skip to Step 6.
5. Slide the magnet assembly along its adjustment slots until the feeler gauge fits snugly
between the flywheel and the magnet coil.
6. Tighten the screws that secure the magnet assembly to the frame (see Diagram 5-1).
7. Repeat Steps 2 through 4 for the remaining magnet assembly.
8. Install the pan on the base of the cycle. Return the cycle to its upright position.
9. Check the operation of the C844 as described in Section Four.

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Diagram 5-1 Adjusting the gap between the flywheel and magnet assembly

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Procedure 5.2 - Measuring the Resistance of a Magnet
WARNING
Always turn off the C844 with the ON/OFF switch and unplug the power cord from the wall
outlet before you service the cycle.
Procedure
1. Place the C844 Cycle on its front end. Remove the pan from the base of the cycle.
2. Set the ohmmeter to a range that will conveniently read 125 ohms.
Caution
Remove power from the C844 before you measure magnet resistance.
3. Remove the wires from the terminals on the top magnet. Measure the resistance between
the two terminals.
Note:
The resistance of the magnets will be higher than optimum (90 - 110 ohms) when they are
warm. Take resistance measurements when the magnets are at room temperature.
4. If the resistance measures significantly less than 90 ohms or significantly more than 110
ohms . . .
THEN . . . OTHERWISE . . .
Replace the magnet as described Connect the wires to the magnet.
in Procedure 7.13. Then continue with the next step.
Note:
The C844 magnet cable assembly is shown in Diagram 5-2.
5. Repeat Steps 3 and 4 for the remaining magnets.
6. Install the pan on the base of the cycle. Return the cycle to its upright position.
7. Check the operation of the C844 as described in Section Four.

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Diagram 5.2 C844 Magnet Wiring

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Procedure 5.3 - Inspecting and Adjusting the Gap Between
Upper and Lower Couplers
WARNING
Always turn off the C844 with the ON/OFF switch and unplug the power cord from the wall outlet
before you service the cycle.
Procedure
1. Remove the upright covers from the pedestal weldment.
2. Place a .060" feeler gauge between the upper and lower couplers.
3. If the feeler gauge fits snugly . . .
THEN . . . OTHERWISE . . .
Remove the feeler gauge and rotate Adjust the gap between the couplers
the couplers about 90 degrees. as described in the following steps.
Re-check the gap between the couplers.
Rotate the couplers and check the gap
until you you have checked the gap between
the couplers at four different spots. Skip to
Step 8.
4. Remove the set screw that secures the upper coupler to the gear box (see
Diagram 5-3). If necessary, remove the old loc-tite from the set screw.
5. Adjust the position of the coupler on the gear box shaft until the feeler gauge fits snugly
between the upper and lower couplers.
6. Place a drop of blue loc-tite on the set screw removed in Step 4. Install the set screw into
the upper coupler.
7. Rotate the couplers about 90 degrees, then return to Step 2.
8. Install the upright covers on the pedestal weldment.
9. Check the operation of the C844 as described in Section Four.

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Diagram 5.3 The Upper and Lower Couplers

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Procedure 6.1 - Troubleshooting the Lower and Upper Ribbon
Cables
WARNING
Always turn off the C844 with the ON/OFF switch and unplug the power cord from the wall outlet
before you service the cycle.
Troubleshooting the Upper Ribbon Cable
1. Remove the upright covers from the pedestal weldment.
2. Attach an anti-static wrist strap to your arm, then connect the ground lead of the wrist strap
to the C844 frame.
3. Disconnect the upper ribbon cable from the upper PCA.
4. Disconnect the upper ribbon cable from the lower ribbon cable.
5. Connect the spare ribbon cable between the upper PCA and the lower ribbon cable.
6. Check the operation of the cycle as described in Section Four.
7. If the cycle operated correctly when the spare ribbon cable was installed . . .
THEN . . . OTHERWISE . . .
The original upper ribbon cable is bad; The original upper ribbon cable is not
install a new cable as described in defective; continue with the next step.
Procedure 7.7.
8. Disconnect the spare ribbon cable from the upper PCA and the lower ribbon cable.
9. Reconnect the original upper ribbon cable.
10. Place the C844 Cycle on its front end. Remove the pan from the base of the cycle.
11. Disconnect the lower ribbon cable from the lower PCA.
12. Disconnect the lower ribbon cable from the upper ribbon cable.
13. Connect the spare ribbon cable between the lower PCA and the upper ribbon cable.
14. Check the operation of the cycle as described in Section Four.