Datex-Ohmeda CAPNOMAC ULTIMA, Service Manual

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CAPNOMAC ULTIMA
TM
SERVICE MANUAL
6-15
6.4.4
Gas measurement troubleshooting
Table 6.2 Gas sampling system troubleshooting chart
SYMPTOM
POSSIBLE CAUSE/REMEDY
No response to any
gas
Sampling line or water trap blocked. Internal tubing (constriction
cassettes) blocked or loose.
Water container loose. Pressure valve malfunction. Pump failure.
Supply voltage missing (power supply board failure)
A/D converter faulty.
No response to
neither CO
2
, N
2
O
nor AA
Chopper motor not running.
IR lamp failure. Check the IR lamp resistance (approximately
3.5 Ohm) and the lamp voltage (4 VDC min). If there is no
voltage, check the LAMP ON signal from the ACX measuring
board (connector Xl pin b13). If the line is high the mosfet V7 on
power supply board is faulty, if low, the chopper motor is
probably stalled. Check for timing pulses from the preamplifier
board.
AGC amsrplifier (A4) faulty. Coarsely erroneous or missing
reference voltage. Timing pulses missing.
Either CO
2
, N
2
O or
AA response missing
Analog switch faulty or control pulses missing.
Other components fault in the measuring electronics. Check by
following the signal with an oscilloscope along the amplifier chain.
No O
2
response
O
2
measuring unit tubes loose or blocked.
O
2
measuring unit connecting cable loose or faulty.
O
2
measuring unit internal tubings blocked by water. Disconnect
O
2
measuring unit tubings and try to remove water by pumping air
into the connector “OUT”.
O
2
measuring unit faulty. Replace.
Analog multiplexer faulty.
Zeroing of CO
2
N
2
O
and/or AA fails
Measuring bench contamination.
Replace ACX measuring unit or try to clean the measuring
chamber as per instructions 6.4.13.
Strong drift in all
gases Leak in sampling line or internal tubing (especially in conjunction
with too low readings).
AGC malfunction. Check analog switches and control pulses.
(Continues)
January 15th, 1997/6