Teledyne MX300 - Manual (Page 34)

Service Instructions MX300
Teledyne Analytical Instruments 26
Symptom Why What To Do
C) The sensor output has fal-
len to a level where it is no
longer usable. Replace
sensor.
The oxygen reading
fluctuates or appears to
be incorrect. The sample pressure
may be changing. A) During calibration, make
sure there is no restriction
on exhaust side of sensor. If
the reading changes with
flow, the sensor is pressu-
rized or there may be a leak
in the system.
B) If a high degree of accuracy
is desired, or the concentra-
tion of O2 being analyzed is
in excess of 40%, calibration
with 100% is recommended.
C) If humidified gas is used to
ventilate the patient, water
vapor actually dilutes the
gas. See Section 2.3. .
D) If a blender is used, check
its calibration.
The unit has stopped
working and the LCD is
displaying alphanumer-
ic characters. The MX300 unit is
equipped with an elec-
tronic "watch dog,"
which analyzes the
circuitry within the unit
for potential faults and
renders the unit in-
operable until the con-
dition is corrected. (See
Watch dog section)
Several conditions can
activate the "watch
dog." Dropping the unit,
poor battery connec-
tions, and radio fre-
quency interference are
the most common
causes. See the watch
dog section for addi-
tional information
A) Disconnect the batteries and
inspect the contacts for cor-
rosion. Reconnect the batte-
ries. If the unit functions
properly, calibrate the unit
and reset the alarm values.
B) Try a new set of batteries.
C) Increase the distance be-
tween the unit and any
source of radio frequency in-
terference. The sensor ca-
ble is a prime source of
pickup as it can act like an
antenna. Relocate the sen-
sor cable and if possible
change its coiled length to
“de-tune” its antenna effect.
Placing the cable in a differ-
ent position may also help.
No display. A) Batteries expired.
B) Bad battery connec-
tion.
A) Check/replace batteries.
B) Check battery connections.