Nellcor N-180, Manual

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N-180 Pulse Oximeter Service Manual
3-20
• BATT IN USE (LD1)
• LOW BATT (LD2)
• PULSE SEARCH (LD3)
• NEONATAL (LD4)
• HIGH SAT (LD13)
• LOW SAT (LD14)
• HIGH RATE (LD15)
• LOW RATE (LD16)
• AUDIO ALARM OFF (LD17)
and operational information,
• pulse amplitude ( LD5 AND LD6)
• oxygen saturation (LD7, 8 AND 9)
• pulse rate (LD10, 11, AND 12)
Pulse amplitude is represented by active segments of two light bar LEDs that
are stacked vertically. Each light bar has ten segments but only eight of the
respective segments are used.
Oxygen saturation and pulse rate readings come from two banks of seven-
segment LEDs. These LEDs have green and red elements.
Front Panel Controls
Controls are mounted on the front and rear panels of the monitor. Control
signals are found on the CPU PCB, the LED Drive PCB, and the front panel
membrane:
• Alarm push button assembly
• Control knob
• ON /STDBY switch
Alarm Push Button Assembly
The alarm push button assembly has five membrane switches and a flat
cable. The membrane switches and connecting cable are part of the monitor
front panel assembly.
Control Knob
The control knob connects to a sealed, two-phase rotary encoder mounted
behind the front panel. Encoder outputs are
ROTSWA
and
ROTSWB
, which
stands for phase A and phase B. The relationship of the phase A and phase B
output signals from the encoder, relates whether the knob is rotating
clockwise or counterclockwise. The amount of rotation encodes the
corresponding amount of desired change.
ON /STDBY Switch
The ON/ STDBY switch is mounted on the front panel. The three switch
contacts are connected to CN5 on the LED Drive PCB.
AC Power Input and Control
Alternating current input and control elements consist of the AC power input
and control unit (which includes the input receptacle) the Power switch, two
fuses, and a built-in EMI filter. The fused AC routes to the primary of the
power transformer. The filter reduces conducted line noise.