Sinclair SCV-1400EB, Service Manual

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For SCV-750EB, SCV-1400EB and SCV-1800EB:
E2
Communication wires X Y E have short
circuited, disconnected or are
misconnected 1
Yes
Reconnect the communication wires
No
Communication wires X Y E are not
connected in a daisy chain
Yes
Connect the communication wires in a
daisy chain
No
Wires between outdoor main PCB and
electric control box communication
terminals block are loose
Yes
Ensure the wires are connected properly
No
Interference from high voltage (220V or
higher) wires
Yes
Ensure the communication wires and high
voltage wires are separated
No
Communication wires are close to a source
of electromagnetic radiation such as
transformer or strong fluorescent lamp
Yes
Remove the source of interference, or add
additional shielding to the communication
wires
No
Damaged control box communication
terminals block
Yes
Replacing electric control box
communication terminals block resolves
the error
No
The length of communication wire is over
1200m
Yes
Reduce the wire length to less than
1200mm or strengthen the signal
No
Replace main PCB or user interface
Notes:
1. Measure the resistance among X, Y and E. The normal resistance between X and Y is 120Ω, between X and E is infinite, between Y and E is infinite.
Communication wiring has polarity. Ensure that the P wire is connected to P terminals and the Q wire is connected to Q terminals.
2. Check whether the communication wires X, Y and E between units have disconnected or are misconnected.