Service manual

Revision D 4-3
Troubleshooting : Power PCB Theory
Series 2000 Treadmill
409110-004
Power PCB Theory
General Description
The 800334-002 power board and the 800320-001 control board
function together as part of the electronics box to control the Series 2000
Treadmill. The power board contains the following:
■
Mains components
■
Isolation transformer
■
Elevation and drive interface circuitry
■
Speaker (for error codes)
■
Serial control links
The serial control links receive inputs from a stress system controller
along with feedback from the treadmill sensors, send the inputs to the
control board, and then receive the control signals for the drive and
elevation motors.
Power Distribution/
Isolation
The power board receives 185 V to 265 VAC power (nominal 220V). The
isolation transformer supplies 5 V to both the isolated communication
link and the control board.
Bypass caps are distributed across the board to minimize EMI and
power supply noise. All other supplies are created on the 800320-001
control board.
STOP Circuitry
When the belt is moving, pushing the normally-closed STOP switch
activates (and latches) the dynamic braking on the drive system. This
takes place as soon as the stop relay K3 is released. The K3 relay also can
be released with a processor RESET* or when the +5 voltage drops too
low.
When a stop occurs, the 4538 timer and frequency-to-voltage converter
disables the output speed (0-10 .3V) for 2.2 seconds and signals the
processor that a stop occurred, even if the switch was only momentarily
depressed.
Frequency-to-Voltage
Converter/Amplifier
The 4538 receives variable frequency (0–2 kHz) pulses from the
processor timer and converts them to 470 µs pulses. The 470 µs pulses
are applied to a low-pass filter/integrator (output 0–5 volt) and passed
through a noninverting op amp (Gain=2) to produce a 0–10.3 volt drive
signal. The drive signal is sent to the drive system as an analog-
requested speed voltage. The circuitry can be disabled for 2.2 seconds
by a system RESET*, a BRAKE* signal, or by releasing the stop relay. This
permits the watchdog timer to maintain a zero-speed command to the
drive during system power-up and guarantees a zero-speed command
during stop conditions.