Headframe Assembly; Input Power Module; Drive Board; Transformer Assembly - Cardiac Science ST 55 Service Manual

Headframe Assembly

The headframe assembly consists of the following components:
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Input power module

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Drive board assembly
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Transformer assembly

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Drive motor assembly

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Grade motor assembly
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Grade system consisting of a pinion shaft, rack gears, feedback potentiometer, and
limit switches.
Input Power Module
The input power module receives line power from the power outlet. All treadmills sold for
use in the United States and Canada use 115 or 230 VAC power. All units sold for use in
Europe use 230 VAC power. The power input module also has a connector for use with
the emergency stop switch. The emergency stop switch is an optional item on non-CE-
marked units but is standard on units sold with the CE mark.

Drive Board

The drive board on the AC Drive Module uses line power to develop 300 VDC that is
then used to create three-phase power for the drive motor assembly. The frequency of the
three-phase signal sent to the drive motor determines the drive motor rotational speed.
The motor current draw is a function of the torque load placed on the motor through the
deck assembly by the user.
The drive board on the AC Drive Module also uses AC power to generate a half wave
rectified signal used to drive the grade motor. Two solid state relays drive the grade motor:
one in the direction of increasing grade, the other in the direction of decreasing grade.
Transformer Assembly
The transformer provides electrical isolation between the primary and secondary voltages.
It also provides stepped down voltages for use with the control electronics.
Drive Motor Assembly
The drive motor, which is driven by the drive board, delivers torque and speed to the front
roller of the treadmill through a poly-V drive belt and a set of appropriate speed reduction
pulleys. A flywheel, integral to the motor poly-V pulley, is used to average the pulsing
runner loads.
TM 55/65 Treadmill 4.0
Headframe Assembly
70-00298-01 A 3-3