Nellcor NPB-40 Service Manual page 18

Section 4: Troubleshooting
4-4
Table 4-1: Troubleshooting Guide (Continued)
Symptom
One or more keys CPU PCB has failed.
on the front panel
keypad does not
work. (Continued)
One or more An LCD PCB
display segments component has
does not work. failed.
Flex circuit between
LCD and LCD PCB
has come loose.
Beeper does not The beeper has been
beep for pulse turned off or its
indication or no volume is turned
sound can be heard down too low to hear.
from the beeper.
The holes for the
beeper on the back of
the NPB-40 are
blocked.
The external output
port on the CPU PCB
has failed.
The beeper on the
LCD PCB has failed
Pulse rate or SpO The SpO
2
value is not not connected
displayed and the properly.
unit is on.
The SpO
failed.
A component on the
LCD PCB has failed.
A component on the
CPU PCB has failed.
LCD backlight does The Display Light
not come on when key on the front
the Display Light panel keypad is
key is pressed. defective.
The backlight LEDs
on the LCD PCB
have failed.
The unit shuts off The batteries are at
when the LCD or near a voltage too
backlight is turned low for the NPB-40 to
on. operate.
Probable Cause
Replace the CPU PCB with a
known good PCB.
Inspect the LCD PCB
components and circuit board
for cracking, burning, or damage
and replace the LCD PCB if any
are found.
Inspect the flex circuit between
the LCD and the LCD PCB has
come loose and replace the LCD
PCB if loose.
Replace the LCD PCB with a
known good PCB.
Turn the beeper back on.
Clear the holes for the beeper on
the back of the NPB-40.
Replace the CPU PCB with a
known good PCB.
Replace the LCD PCB with a
known good PCB.
sensor is Connect the SpO
2
NPB-40.
sensor has Replace the SpO
2
known good SpO
Replace the LCD PCB with a
known good PCB.
Replace the CPU PCB with a
known good PCB.
See "One or more keys on the
front panel keypad does not
work," above.
Replace the LCD PCB with a
known good PCB.
Install new batteries.
Corrective Action
sensor to the
2
sensor with a
2
sensor.
2