93-520-20 Issue 3.3 Page 54 of 60 CirrusPro Engineer’s Manual
7 LED Fault
The unit has detected that insufficient light is being received at the photodiode. This probably means
that the LED, Photodiode or associated wiring has a fault.
The chamber LED lights when a sample is taken, this can usually be seen illuminating through the
mounting medium. The LED current can be checked in the Service Menu on the PC or display unit
(fault levels at < 257uA and > 5.7mA).
If the current is high and the LED illuminates, remove and clean the LED and Photodiode. If the fault
persists, replace the photodiode first, then if not successful replace the LED.
If the current is high and the LED does not illuminate the wiring or the LED is open circuit.
8 Water Fill Fault
The unit has detected that the water fill process has been unsuccessful or there has been no water fill
for more than 21 days.
Check the thermistor:
The two-way header to the thermistor has become detached.
The thermistor is faulty; check the resistance of the thermistor, approximately 8k, at room temperature.
Replace the thermistor (or cloud chamber) if necessary.
If there is no problem with the thermistor, the controller PCB should be changed.
If greater than 21 days since the last fill and everything has been checked, check if the environment is
too cold or humid.
9 Airflow Fault
The unit has detected an out of range airflow, or an out of range airflow has been saved to the unit.
Via the Commission menu, enter the Accept air flow box to identify the airflow. The airflow should
be 15-85%. If it isn’t then either the pipework has changed, or the airflow was not set correctly during
commissioning (too little settling time may have been allowed) or a pipe has become detached or
blocked. If the airflow is too high (>85%) and the pipework is correct, then reduce the airflow by
dropping the output to the blower.
If the airflow is too low, then either the blower is malfunctioning, or the unit is out of specification for
pipe work, and more holes are required in the pipework to increase the airflow. After remedial action
has been taken, transport time and fire testing should be carried out to confirm the operation of the
transport system.
10 Stack Overflow
This is indicated if a problem has been detected with the micro controller program or the Read Only
Memory (ROM). This is a serious failure and usually requires a replacement controller geartray
assembly.
11 Unit Isolated
The units Alarm Relays have been isolated via a monitored input. See Section 3.2.12.
12 Low Supply Voltage
The unit has detected that the power to unit is low (less than approx. 21Volt). Check the voltage levels
at the unit and the power supply. Ensure that all connections are good.
13 Algotech Fault
The Algotech Thist values are too high. Check current levels and change the gain. Send the data to
set Background level.
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