Life Fitness LS 9100 Service Manual page 3

Life Fitness 9100/9500HR Belt Drive Stairclimbers
THEORY OF OPERATION
The electronics system of the Life Fitness LS 9500HR and LS 9100 belt drive stairclimbers is made up of three
distinct modules; the Power Entry Module, the Display Console, and the Power Control Board.
120 volts AC enters the Power Entry Module. It passes through a transformer and is converted to 14 volts AC. The
14 volts AC is applied to the Power Control Board at connector J4, pins 1 and 2. The voltage passes through a
bridge rectifier, BR1 and is converted to an unregulated positive DC voltage. This unregulated voltage will vary from
11 volts DC to 18 volts DC depending on the wall supply and load. This voltage can be measured by placing the
positive probe of your DVM on Positive Test Point at BR1 and the negative probe on the negative Test Point at
BR1.
The other voltage developed on the Power Control Board is a regulated positive 8 volts DC. The regulated 8 volts
DC is developed by transistor (Q2) . This voltage can be measured by placing the positive probe of your DVM on
the collector (case) of Q2 and the negative probe on the anode of D1.
This 8 volts DC is supplied to the Console at connector J1, pin 4 and is used to power the LED's. The 8 volts DC is
also used as a supply voltage for the positive 5 volt DC regulator (U1) on the Console board, which is VCC for the
Microprocessor. The Keypad entry (user's input), Life Pulse (9500HR only), and Telemetry are all processed by the
Microprocessor.
The Console, by pulse width modulating the field control line, sends a signal to the Power Control Board at J1, pin
1. The Power Control Board switches the field current to the Alternator, through Q1. This field current along with
the energy supplied by the user is sent to the Load Resistors. This places resistance on the rotation, thus providing
the load sensation felt by the user.
The Alternator also provides the source for the RPM sensor circuit. The AC tap output on the Alternator enters the
Power Control Board at J2, pin 3. This AC voltage is wave conditioned and outputted at connector J1, pin 2 to the
Console connector P2, pin 6. Where it is processed and displayed by the Console.
WARNING:
C9
U3
C5
HS1
C11
J4
C13
14 VAC
U1
R8 R5
PIN_PADSTACK
C12 R4
J4
R16 R6
C14
C6
D6
R7 D7
R3 R15
R14 C7
R17
R18
PIN_PADSTACK
J1
8 VDC
Pin 4
8VDC
CONSOLE
See Wiring Diagram for more detailed information
RISK OF FIRE,REPLACE FUSE AS MARKED.
C
LIFE FITNESS A080-92167-A000 1997
Q1
HS4
ADSTACK _P N PI
PIN_PADSTACK
R2
R9 R1
Q2 HS3
PIN_PADSTACK
Q2
AC
+
Pos BR1
+
PIN_PADSTACK
POS AC
PIN_PADSTACK
STACK STACK PIN_PAD STACK PIN_PAD STACK PIN_PAD STACK PIN_PAD STACK PIN_PAD STACK PIN_PAD PIN_PAD _PADSTACK PIN
_
D1
Neg
J2
Pin 3
RPM
ALTERNATOR
C8
Neg
_
BR 1
18 VDC