Ref: REFLEX/SCANFLEX MANUAL
EDITION 1: JULY ’97 43
G) Relay 3 l.e.d. on:-
Used to indicate 'LOSS OF ECHO' on any or all points of measurement. Also
indicated by 'LOSS OF ECHO' being displayed on the Controller display, replacing
the bar graph.
'LOSS OF ECHO' on all points:-
1. Check that the Multiplexor Unit is powered up.
2. If the neon by terminal 22 on the Controller does not flash disconnect the
transducer cable at the Controller. If the neon now flashes this indicates a
short circuit in the link between the Controller and the Multiplexor. If the
neon does not light with the above transducer link disconnected check fuses
F1 and F2 on the bottom PCB.
3. If the neon does light, check that the green 'comms' l.e.d. on the Multiplexor
unit is flashing. If not check the RS485 link (refer to Page 9). Also check that
the unit selector SW1 is not set to zero, as this will prevent the connection of a
transducer (refer to page 10).
4. If the neon does light, connect a known good transducer to the Controller and
check the operation of the unit at various distances. If it does not work
correctly the Controller is faulty.
5. Check the RG62AU connection between Controller terminals 19 and 20 and
TB3 on the Multiplexor.
6. Check on the Controller that the ST6 eprom is seated correctly at U6 on the
bottom PCB.
'LOSS OF ECHO' on one point:-
1. Select Manual Scan at Pr.53 and the faulty point.
2. If the Controller neon does not flash whilst the Multiplexor is on the
measurement point, disconnect the transducer from the Multiplexor. If the
neon now flashes there is a short circuit in the cabling between the Multiplexor
and the transducer.
3. If the neon does flash, connect a known good transducer on to the Multiplexor
for the measurement point, and check for correct operation. If the point
remains in 'LOSS OF ECHO' check that the relay on the Multiplexor for the
point is operating correctly, the adjacent red l.e.d. should be lit.
4. If the good transducer works, re-connect the original transducer and
programme the Controller for transmitter test (Pr.77) for that point. Check if
the transducer is 'clicking', if not there may be an open circuit in the cable or
the transducer is faulty.
5. Check that empty distance at Pr.4 is correct and that the target is within range.
'LOSS OF ECHO' at short distances from the transducer:-
1. 'LOSS OF ECHO' at short ranges can be caused by poor quality return echoes.
Check the surface conditions for foam, turbulence etc. If these conditions
exist, contact Hycontrol.
2. Change Pr.66 from 2 to 1. This should give adequate gain to clear the
'LOSS OF ECHO'.
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