Service manual

Revision D 4-4
Troubleshooting : Power PCB Theory
Series 2000 Treadmill
409110-004
Start/Stop Circuitry
When COAST* and BRAKE* are not active (low), the START pulse
command can engage the drive system. These signals are level
converted from CMOS/TTL (0–5 V) levels to (-15 V–0 V) logic by the
74HC14 drivers and level shifting transistors. The 750-ohm resistors
limit the maximum current to 27 mA (+5V -(-15V) /750) and the typical
current to 5.7 mA (+5V - (0.7V) /750). The diodes limit the output voltage
to 0.7 volts. These drivers are connected to the opto-couplers within the
drive system.
The COAST* and BRAKE* signals override the START pulse.
Elevation Relays
A direction control and an enable relay control the elevation motor. A
change in direction should only occur when the elevation motor is
stopped. The enable relay is disabled by the normally-closed limit
switches at the end of travel to prevent damage to the motor. The
LIMIT* signal goes low when a limit switch is activated in a particular
direction.
Drive Connector
Inputs from the brushless motor hall sensor and the control signals are
combined to provide signals to run the drive system. The drive system
provides fault output, which is reset by pulsing the COAST* signal.
Hall Feedback
Five hall sensors monitor the position and speed of the drive motor. The
drive control uses the three primary sensors (HALL1, HALL2, HALL3) to
commutate the three-phases of the DC motor. The other two hall
sensors (HALL4 & HALL5) provide speed and direction feedback by
quadrature to the drive and to the control. HALL1and HALL3 provide
about 4 pulses per revolution and HALL4 and HALL5 provide about 30
pulses per revolution. The higher frequency HALL4 and HALL5 signals
maintain better speed regulation at low motor speeds.
These 5-volt hall signals are squared-up by 74HC14, which is protected
by filter caps, limiting resistors, and Zener diodes.
Power Inlet, Drive Power
Outlet, and Mains
The power comes in on the terminal block, gets fused and filtered, and is
distributed to the isolation transformer and out to the drive system.
Externally accessible 0.5ASB fuses are provided for the control portion
of the circuitry. The 20 Amp internal fuses are for the drive section and
are intended to protect the wiring from major faults within the drive
system. Spacings for creepage and isolation are critical in this whole
section.
Control Board Connector
The control board connector provides 0.5-inches of stand-off spacing
for the rear entry connector on the 800320-001 board.