GE Giraffe OmniBed Carestation CS1, Service Manual

Page: 101 / 308

Chapter 5: Troubleshooting
Servo Controlled Oxygen
Service Manual 5-19
Oxygen System
Failure 1 The sensor plug
thermistor
temperature
reading is out of
the range:
15C-55C. Device is cold:
<15 degrees C. Allow device to warm up.
Cooling fan is not
running when the
sensor housing
temperature gets
above 50 degrees. Test the cooling fan. Refer to the
Tips section (
5.4.4 ).
Defective sensor plug
thermistor or cable Disconnect the cable and measure
the resistance of the thermistor
between J85.4 and J85.5. Refer to
R/T chart (the temperature to
resistance curve) in the Tips
section (
5.4.4 ). If sensor is shorted,
open, or values don’t agree with
the R/T chart, replace the sensor
plug assembly or the cable.
Defective servo
O2 board If resistance is in range replace the
servo O2 board.
Oxygen System
Failure 2 The RH reading is
out of valid
range: 1-99.
When out of
range it displays
0 in service Mode. Defective sensor plug Measure the humidity sensor
voltage between J85.2 and J85.1. If
the voltage is outside the range of
0.7V- 4.0V, replace the sensor plug
assembly.
Defective servo O2
board If it is in the correct range, replace
the servo O2 Board.
Oxygen System
Failure 3 The checksum
test performed
during power up
testing failed. Defective
Microcontroller Replace microcontroller U6 on the
Servo O2 board.
Oxygen System
Failure 4 Analog to digital
converter circuit
self test failed.
The reading of
Vtest is out of the
valid
range:1.216V-
1.254V. Defective Servo O2
board Replace servo O2 board.
Check O2 supply After calibration,
both supply
valves are
opened and after
approximately 20
seconds, sensor1
reading is not
greater than
23%. O2 supply not
connected Verify O2 supply, minimum 45psi
(310kPa) is connected to the inlet.
Kinked hoses in sensor
housing Check hoses.
Alarm Message Meaning Cause Action