Operating and service manual
70 of 222 pages
109
Tusda 1 open
Warning
Description
USDA 1 Temperature Sensor Open Circuit
Cause
Indication of loose connection, defective or lack of USDA 1 temperature sensor
Trouble
shooting
Possible causes:
•
Temperature sensor Tusda1 or its cable defective.
•
X1 cable is defect.
•
Defective plug inside or cable on the unit backside.
•
Controller PCB defective.
Accompanied alarms:
•
N/A.
Trouble shooting:
1) Disconnect the sensor cable for sensor Tusda1 from the connector on the
interface/terminal block PCB, according to the wiring schematics inside in
the control cabinet.
2) Measure the resistance between the two wires.
a) If the resistance is more than 1.5 MΩ, the cable or the plug on the
backside of the unit or the sensor is defect. Check plug before replacing
the sensor and cable.
b) If the resistance matches the resistance and temperature in
Tables
starting p.204, the temperature sensor and cable are ok.
3) Measure the voltage over the connector for Tusda1. It should be between
4.80 and 5.05V DC
a) If the voltage is inside the above range, connect sensor again. Measure
the voltage over the sensor and check voltage/temperature according to
table
Tables
starting p.204
b) If the voltage is outside the above range, the controller PCB is defect or
other sensors may be defect and pulling the voltage down. Check other
alarms and see
Trouble shooting for Star Cool Controller
p.56 before
replacing controller door.
Criteria
Value below low alarm limit -60°C (-76°F) and the sensor reading has been in the valid
area since power-up.
Controller
action
None
Log
X
Alarm
(X)
Alarm light
Off
Consequence
May be incomplete USDA data logging.
If activated Cold Treatment (CT), it will be affected.
Elimination
When sensor value becomes valid, it is marked as inactive in the alarm list and may then
be deleted.
Log data
Parm 1
Parm 2
Parm 3
Parm 4
Parm 5
Active/Inactive Low limit
High limit
Present
