D. Display Power Test
The display does not have a power indicator LED. If the display LEDs don't
light, detect power to the display by placing probes on the capacitor near
the data cable. Normal reading: 5 VDC. If there is power here but the LEDs
don't light, replace the display board. If there is no voltage here, inspect
the data cable and drive board.
E. Speed Sensor Test
Operation
As the drive pulley rotates, a reed switch passes a magnet. Each time the
reed switch passes the magnet, the circuit is closed, creating a signal to
the display. The display main IC translates this signal into the speed and
distance readout.
a voltmeter to the audible continuity setting.
Symptom of Malfunction
A sign of a failing speed sensor circuit is no speed and distance on the
display. Resistance is also lost. The display could black out altogether.
Troubleshooting
1. LED test: Rotate the drive pulley so the magnet and reed switch pass by
each other. Normal: CLK LED on the drive board lights when the magnet
and reed switch pass by each other.
2. Voltmeter test: Put Place
probes on the two speed sensor wires. Rotate the drive pulley so the reed
switch passes by the magnet. Normal: The meter beeps, indicating
continuity, when the magnet and reed switch meet. This indicates that the
magnet/reed switch are OK.
3. Test the magnet by seeing if it attracts metal.
4. If the magnet or reed switch fail these tests, replace it.
Note: C51, C52, C53 bikes have two magnets on the drive pulley.
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C52R/C52U C53R/C53U Bike Troubleshooting Notes - April 20, 2004