Electronic System - Life Fitness 8500 Service Manual

Life Fitness Models 8500, 9100, and 9500HR Cross-Trainers
THEORY OF OPERATION
The electronic system on the rear-drive crosstrainer is made up of three main functional blocks: 1) Console, 2) HR
telemetry, and 3) Alternator, Power Control Board, and Load. In addition, the 9500 model has Lifepulse contact HR.
The following is a description of each functional block:
CONSOLE
The system voltage (6-7.5Vdc) enters on connector P2 pin 1 and is used to power the LEDs and provide a supply
voltage for the 5V-regulator circuitry used to power the microprocessor section.
The Keypad entry (user's input), Lifepulse (9500HR only), and Telemetry are all processed by the microprocessor.
The console outputs a PWM signal to the power control board to control the duty cycle of the load.
ALTERNATOR, POWER CONTROL BOARD, AND LOAD
Using the PWM signal from the console, the power control board switches the current on and off at the load via
Q1. The control board also regulates the alternator voltage using the U1 comparitors. Q3 and Q9 are used to
sense the reed switch actuation (autostart feature).
POLAR
HR telemetry is implemented via a Polar receiver located in the rocker arm shroud at the front of the unit. The
Polar receiver connects to the console at connector P7.
LIFEPULSE (9500 ONLY)
The handlebar electrodes connect to the console board at connector P9. Pins 1 and 4 are signal, pins 2 and 3 are
circuit reference.