Precor C960 Service Manual page 36

16. 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 a 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 20. If no AC voltage is on the lift capacitor, continue with step 17.
17. Set the treadmill circuit breaker in the "off" position. Remove the 2 amp lift fuse (F2) from the
lower PCA. Using an ohmmeter, measure the fuse resistance. The fuse should measure
approximately 1W or less. If the fuse is open (•) or significantly higher than 1W, replace the
fuse. If the fuse was bad, perform the test in step 18 before applying power to the lift. If the
fuse was good continue with step 19.
18. Using an ohmmeter, measure the resistance across the lift capacitor terminals. The lower
PCA resistance should be extremely high (megohms), the capacitor resistance should be
extremely high (megohms) and the lift motor winding should read approximately 32W (120
Vac units) or 115W (240 Vac units). Therefore, if the measurement is significantly lower
than 32W or 115W, disconnect both red leads from the lift capacitor. Measure the resistance
between the black leads on the lift capacitor and red lead to the lower PCA. If it measures
significantly low, replace the lower logic/lift PCA. Measure the resistance between the black
leads on the lift capacitor and red lead to the lift motor. If it measures significantly low,
replace the lift motor. Measure the resistance between the black leads on the lift capacitor
and other terminal of the lift capacitor. If it measures significantly low, replace the lift
capacitor.
19. At this point the lift fuse is good, but there is no AC voltage on the lift capacitor when the lift
is actuated. There are three potential causes for this condition. They are lower logic/lift PCA,
ribbon cable or upper PCA. There are no good means of troubleshooting these components
other than substituting known good components. Replace only one component at a time. If
the component that you replaced does not correct the problem, replace the original
component. Try substituting the lower PCA first, the ribbon cable second and the upper PCA
third.
20. If you have performed all of the above procedures and have been unable to correct the
problem, call Precor Customer Support.
21. Using an ohmmeter, measure the resistance across the lift capacitor terminals. The lower
logic/lift PCA resistance should be extremely high (megohms), the capacitor resistance
should be extremely high (megohms) and the lift motor winding should read approximately
32W or 115W. If it measures significantly high or open (•), replace the lift motor.
22. If the resistance measurement in step 6 was approximately 32W (120 VAC units) or 115W
(240 VAC units), replace the lift capacitor. If you have performed all of the above procedures
and have been unable to correct the problem, call Precor Customer Support.
23. Typically, when the lift is able to physically move but causes a lift error, the problem is in the
lift position identification system (lift potentiometer or lift calibration).
C960 Series Commercial Treadmill
Page 36