This error monitors the treadmills power bit reading when the treadmill was operating at speeds
of 1 mile per hour or less. Power bits indicate the relative time that the motor controller drive circuit
is turned on. Therefore power bits is an indication of the amount of power the load is
demanding from the motor controller. Error 20 indicates that at a speed of 1 mile per hour or less
an excessive amount of power is being demanded from the motor controller for an excessive
period of time.
1. The treadmill user (especially a heavier user) is standing on the drive belt as they start the
running belt into motion. Starting the running belt into a very heavy load can cause the error
2. The running bed and/or running belt is badly worn and the error 20 occurs when the user
steps onto the running belt.
3. The drive motor brushes are badly worn and not making sufficient contact with the drive
motor commutator. The error 20 occurs when the user steps onto the running belt. The
treadmill may also bog down when the user steps onto the running belt.
4. On treadmills utilizing an SCR motor controller, a leaky or shorted drive motor filter capacitor
could raise the current demand sufficiently to cause the error 20.
5. On treadmills utilizing an SCR motor controller, a leaky or shorted drive motor inductor could
raise the current demand sufficiently to cause the error 20.
6. A shorted or de-magnetized drive motor is causing the high power demand.
1. The user should be instructed to straddle the running belt and start the treadmill at a low
speed (1 mile per hour or less) and then step onto the running belt.
2. A clamp-on A.C. ammeter must be used to determine the amount of A.C input current being
drawn by the treadmill under no load and loaded conditions. The current readings can be
used to determine the condition of the running belt and/or running bed. These same readings
should be taken on a similar unit with a known good running belt and running bed. Those
readings can then be used as a benchmark for future use. Replace the running belt and/or
running bed as required. Remember, many running beds are double sided and the bed can
be flipped over rather than being replaced.
3. Replace both drive motor brushes.
4. A clamp-on ammeter should be used to measure the A.C. input current at no load. The filter
capacitor should then be electrically isolated from the drive motor circuit. The drive motor
leads must be kept intact so that the drive motor will operate with the filter capacitor removed
from the circuit. The no load A.C. input current should be measured again, if the A.C. input
current is significantly lower, replace the filter capacitor.
5. Use the same procedure as in step 4 above, except remove and isolate the inductor from the
drive motor circuit instead of the filter capacitor.6. A known good drive motor must be substituted for the existing drive motor.