59
UUT Problem
Possible Causes
Further Checks
Incorrect or No LCD
output.
LCD Board fault.
Addressing fault either:-
Switch Board or
Main Board (will usually be
accompanied by an audible
alarm if Main Board Processor
has stopped running).
Negative supply to LCD module,
potted down on the Switch Board
from the -12v supply, out of
spec.
Swap or test LCD Board.
Swap or test Switch Board.
Swap or test Main Board.
Check Negative Supply reaches
LCD Module.
No LCD Backlight.
LCD Board fault.
Display Board fault.
Addressing fault either:-
Switch Board.
Main Board.
Swap or test LCD Board.
Check Operation of backlight
switch TR1 and confirm
+Vbacklight is present on PL31
Pin 2 w.r.t Pin 1.
Swap or test Switch Board.
Swap or test Main Board.
Incorrect or No LED
display output.
Note: If a partial loss of the
LED’s is found the fault is most
likely to reside on the LCD
Display Board.
LED Display Board fault.
Addressing fault either:-
Switch Board or
Main Board (will usually be
accompanied by an audible
alarm if Main Board Processor
has stopped running).
No or low +4.5V VDISP supply.
Swap or test LED Display Board.
Swap or test Switch Board.
Swap or test Main Board.
Swap or test PSU Board.
Check supply continuity from
PSU Board to Display Board.
SpO
2
Probe
disconnected error
reported on LCD
(P00 Error).
Faulty Finger Probe.
Faulty SpO
2
Module to Front
Panel cable.
SpO
2
Module fault.
Test with known good sensor.
Swap or check cable continuity.
Swap module and test unit with
Nellcor SpO
2
Simulator.
SpO
2
No signal error
(P55 Error).
Faulty Finger Probe.
Faulty SpO
2
Module to Front
Panel cable.
SpO
2
Module fault.
Test with known good sensor.
Swap or check cable continuity.
Swap module and test unit with
Nellcor SpO
2
Simulator.
