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1. To locate the faults in Network
1.If the indicating lamp of fiber optical transceiver or optical module and twisted pair cable port is
light?
a. If the transceiver optical port (FX) indicator is not light, make sure whether the fiber link is a
cross-linked fiber link. A fiber optic patch cord is connected in parallel; the other end is connected
to a cross pattern.
b. If A transceiver optical port (FX) indicator lights but B transceiver optical port (FX) indicator is
not light, then the fault is the A transceiver side. One possibility is: A transceiver (TX) optical
transmitter port is bad and B transceiver optical port (RX) fails to receive optical signal. Another
possibility is: There is a problem in fiber link of A transceiver (TX) optical transmitter port. (fiber
optical cable or fiber optic patch cord may break.)
c. Twisted pair (TP) patch cable indicator is not light, make sure whether the twisted pair wiring is
wrong or the twisted pair connection is incorrect? Please use on-off tester to test. (mind twisted
pair cable indicator of some transceivers will light until the fiber link is connected.)
d. some transceivers have two RJ45 ports: (To HUB) indicates that the cable connect to switch is a
straight line; (To Node) indicates the cable connect to switch is a cross-line;
e. One side of some transceivers with MPR switch: Indicates the cable connect to switch is a
straight line; DTE switch indicates the cable connect to switch is a cross-line;
2.If the fiber optic cable, fiber jumper has been broken?
a. Cable on-off detection: using laser flashlight, sunlight, light to against one side of cable
connector or coupler; see at the other end if there is visible light? If there is visible light, it
indicates that the fiber optic cable is not broken.
b. Fiber optic connection on-off detection: using laser flashlight or sunlight in front of one side of
a fiber jumper, see at the other end if there is visible light? If there is visible light, it indicates that
the fiber jumper is not broken.
3.Whether the half / full duplex mode is wrong?
One side of some transceivers with FDX switch: indicates full duplex; HDX switch: means halfduplex.
4.Using a optical power meter to test
The luminous power of optical transceiver or optical module under normal circumstances:
multimode: -10db-18db; single mode 20 km: -8db-15db; single mode 60 km: -5db-12db. If the
luminous power of fiber optic transceiver is: -30db-5db, then you can determine the transceiver
has a problem.
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