11
- FAULT FINDING
The led indicator 'power ON' is off, ' LCD display' off, other led indicators are off.
Verify
a. mains supply.
b. that power supply before the transformer (220 - 24 VAC) is 24 Va.c..
c. that the 24 VAC power supply lead is correctly connected.
If at start-up:
an alarm led turns on.
the LCD shows no messages or unusual messages.
the buzzer sounds.
Then verify
a. the correct position (polarity) of the eproms (see page 1).
b. that the pins of the eprom are not damaged.
c. that the microprocessor chip has not be damaged: in this case contact the nearest
Service Centre.
Uncertain alarm indication coming from digital input.
Check
the input alarm signal by measuring the voltage value between common terminal "C" and the
terminal corresponding to the digital input "Cn".
In case of continuous current (c.ca 5 Vd.c.) the contact of the connected alarm device is
open. If voltage is 0 Vd.c. the contact is closed.
The controller will indicate an alarm condition on a closed contact if a normally open
contacts logic is used and viceversa.
Wrong reading of input signals
Verify
a. That the probes are correctly connected (see pages 5-6);
b. That the cables of the probe are placed as far as possible from sources of noises (power
cables, contactors, high tension cables, etc.);
c. the connections between interfaces and controller (flat cables) (see pages 2 and 4);
d. That there is not high thermal resistance between sensor and probe socket. If necessary, put
some conductive paste or oil in the socket to ensure the right transmission of temperature.
e. That there is no probe error or controller conversion error.
Checking procedures depend on the type of probe.
Active temperature/humidity probes with signal -1 V/+1 V: measure the proble output
between terminal Bn and M. The probe output is 10 mV per °C/%RH.
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