C55U Repair Manual (Electronics)
Table of Contents
1-1-1. Product Picture - C55U
1-2-1. Display Overlay - C55U
1-3-1. Component Placement - C55U
1-3-2. Component Placement - C55U
1-4-1. Block Diagram - C55U
1-5-1. Cable Connections - C55U Display Board
1-5-2. Cable Connections - C55U Drive Board
1-6-1. LED Indicators - C55U Display Board
1-6-2. LED Indicators - C55U Drive Board
1-7-1. Specification Chart - C55U
2-1-1. Electronics Troubleshooting Chart - C55U
3-1-1. Troubleshooting - C55U No Start
3-2-1. Troubleshooting - C55U No RPM Value
3-3-1. Troubleshooting - C55U No Resistance Adjustment
3-4-1. Troubleshooting - C55U Excessive Resistance
3-5-1. Troubleshooting - C55U Telemetry Heart Rate Malfunction
3-6-1. Troubleshooting - C55U HTR Heart Rate Malfunction
3-7-1. Troubleshooting - C55U Key Malfunction
4-1-1. Testing - C55U Transformer Voltage Test
4-2-1. Testing - C55U Motor Voltage Test
4-3-1. Testing - C55U VR Voltage Test
4-4-1. Testing - C55U Reed Switch/Magnet Test
1-1. Product Picture - C55U
1-1-1
1-2. Display Overlay - C55U
1-2-1
1-3. Component Placement -
C55R/C55U
1-3-1
Telemetry heart rate
board
HTR board
1-3. Component Placement - C55U Lower Compartment
1-3-2
Switch and fuse holder
Magnet
Flywheel
Transformer
Drive board
Reed switch
Motor/VR
1-4. Display Block Diagram - C55R/C55U
1-4-1
Display
Board
Drive
Board
Motor
Reed Switch
SW
Telemetry HR
Receiver
B
oard
Fuse
Power
Cord
HTR Board
Sensor-L
Sensor-R
Transformer
VR
1-5. Cable Connection Picture – C55U/C55R Display Board
1-5-1
To LCD module
To drive board
To telemetry
receiver board
To HTR board
To HTR contact plate
1-5. Cable Connection Picture – C55U Drive Board
1-5-2
To display board
To VR box
To reed switch
To transformer To fuse and power switch
1-6. Indicator LEDs - C55U Display
1-6-1
Telemetry HR board
Lit indicates HR signal
1-6. Indicator LEDs - C55R/C55U Drive Board
1-6-2
LED5 CLK Indicator
During exercise,
LED flashes
LED3 LEVEL UP
Lit indicates increasing
resistance from motor/VR
assembly
LED1 Motor/VR Assembly Power
Lit indicates motor/VR power
supply
LED2 Power Indicator
Lit indicates there is incoming power
LED4 LEVEL DOWN
Lit indicates decreasing
resistance from the
motor/VR assembly
1-7. Specification Chart - C55R/C55U
Function
Detail Note
Main power
Exterior power supply 110V or 220V
Speed detection
Reed switch + magnet
Resistance control
Electronic resistance adjustment via motor/VR assembly control
Resistance type
Permanent magnet
Level range LEVEL 1 – LEVEL 14
Main display
method
LCD
Secondary display
method
WORKOUT LEVEL / TIME
RPM / CALORIES
Program
RANDOM / TRACK / INTERVAL / HILL
Heart rate Telemetry heart rate / contact HTR
User mode USER1 – USER4
Keys Key switches
1-7-1
2-1. Electronics Troubleshooting Chart – C55R/C55U
Malfunction
Circumstance Inspect and Test Components
Notes
No start up Exercise. Display does
not light up.
1. Inspect cable connections.
2. Inspect drive board fuse.
3. Inspect power LED on drive board.
4. Inspect display IC.
1.Fuse
2.Drive board
3.Display
No
strides/min
Exercise. Display RPM
= 0.
1. Inspect all cable connections.
2. Inspect LED5 on the drive board. A. Magnet or reed
switch malfunction. B. Drive board malfunction.
3.Inspect IC installation.
1.Reed switch
and magnet
No
resistance
adjustment
Press LEVEL
<▲>/<▼>. Resistance
doesn’t change.
1.Press LEVEL<▲>/<▼>. Display LEVEL does not
change. Key malfunction.
2.Inspect drive board LED3 or LED4.
If LEDs do not light, inspect cables or replace drive
board.
3.Test or replace VR.
1.VR
Excessive
resistance
Exercise. Resistance is
excessive.
1.Flywheel magnet is stuck.
Telemetry
(wireless)
heart rate
malfunction
Telemetry heart rate
malfunction
1.Inspect heart rate transmitter and its batteries. Replace
batteries if necessary.
2.Inspect heart rate receiver cable connections.
3.Test or replace heart rate receiver cable.
4.Inspect for environmental interference, possibly from
lights or speakers.
1. Transmitter
2. Receiver
HTR heart
rate
malfunction
HTR malfunction 1.Inspect the HTR cable connections.
2.Replace the HTR board.
1.HTR board
Key
malfunction
No key operation, or
constant operation.
1.Replace key switches. Key switches
2-1-1
Troubleshooting
Model:
C55U
Malfunction: No start up
Circumstance: Turn on power; display does not light.
Possible cause: 1. Poor cable connections
2. Fuse blew
Troubleshooting: 1. Inspect all cable connections.
2. Inspect main fuse and power switch area.
3. Inspect drive board indicator LED.
4. Test transformer voltage output.
5. Inspect display program IC.
3-1-1
Drive
Board
Display
Board
SW
Transformer
FUSE
Inspect whether PWR
LED on the drive board
lights
Inspect transformer output voltage
Program IC
Troubleshooting
Model:
C55U
Malfunction: No RPM value
Circumstance: 1. No RPM value
2.Exercise on the bike.
The display shows no reaction.
Possible cause: 1. Reed switch malfunction
2. Poor cable connection
Troubleshooting: 1. Inspect all cable connections.
2. Inspect reed switch and magnet.
3. Inspect CLK indicator on drive board.
4. Inspect the display IC installation.
3-2-1
Display
board
Drive board
Reed switch
Inspect reed switch and magnet
LED5 reed switch indicator
on drive board
Main program IC
Troubleshooting
Model: C55U
Malfunction: Resistance cannot be adjusted.
Circumstance: Press the level key. Resistance does not change.
Possible cause: 1. Key malfunction
2.VR malfunction
Troubleshooting: 1. Press LEVEL<▲>/<▼>. If LEVEL values on
the display do not change, the keys are bad.
2. Inspect LED4 or LED5. If LEDs do not light,
inspect the cable or replace drive board.
3.Test or replace the VR.
3-3-1
Drive
Board
Display Board
VR Set
VR Motor
Inspect UP/DOWN LEDs
Troubleshooting
Model:
C55U
Malfunction: Excessive resistance
Circumstance: Exercise on the bike; resistance is excessive.
Possible cause: 1.The flywheel magnet is stuck.
Troubleshooting: 1. Inspect the flywheel magnet.
3-4-1
Troubleshooting
Model:
C55R/C55U
Malfunction: Telemetry (wireless) heart rate malfunction
Circumstance: Telemetry heart rate malfunction
Possible causes: 1.Telemetry strap battery
2. Telemetry HR receiver malfunction
3. Environmental interference,
possibly from lights or speakers
Troubleshooting: 1.Replace heart rate transmitter
or its batteries
2.Inspect the transmitter receiver board cable
connections.
3.Inspect the heart rate board LEDs.
4.Replace the heart rate board as a test.
5.Inspect sources of interference, such as
lights and speakers.
3-5-1
Display
board
HR receiver
HR transmitter
Telemetry heart rate receiver
board
Heart rate transmitter
(battery location)
Troubleshooting
Model:
C55R/C55U
Malfunction: HTR (contact) heart rate malfunction
Circumstance: HTR malfunction
Possible cause: 1.HTR board malfunction
Troubleshooting: 1.Inspect HTR board
cable connections
2. Replace the HTR board as a test.
3-6-1
Display
Board
HTR Board
Sensor-L
Sensor-R
Troubleshooting
Model:
C55R/C55U
Malfunction: Key malfunction
Circumstance: Press keys; there is no reaction
or keys are constantly activated.
Possible causes: 1. Key cushion is out of place
2. Key switch malfunction
Troubleshooting: 1.Inspect key switches and
cushion placement.
3-7-1
Display Board
Key Switches
Key
Cushions
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