Problem Solving
2–23
2.4.7
Measuring the FI Power
If a failure in the FI port disappears when an FI loopback test is performed, check the
optical signals into and out of the port to determine if they are within specifications.
To measure the power levels of the transmit and receive optical signals at the bridge,
use the SDU optical power meter kit (P/N 29-28384-01). This kit contains an optical
power meter, a receive cable, and cleaning pads. To make the measurements, per-
form the following six steps:
NOTE
If measuring power at a simplex connector (ST), both
the transmit and receive cables must be disconnected in
order to get a proper light-signal pattern and observe
correct power readings.
1. Make sure the bridge is in normal operating mode by placing the External
Loopback switch (switch 7) to the OFF (up) position and removing the loop-
back connector from the FI port (if one is installed).
2. Set up the optical power meter as follows:
a. Remove the protective cap from the input test head.
b. Turn on the meter by pressing the ON/OFF switch.
c. Use the
λ
select switch to select the 1300-nm
wavelength range. The
wavelength value will appear on the LCD display.
3. To ensure a clean test connection, remove the protective caps from the test
cable connectors and use a cleaning pad to wipe the connector faces.
4. To measure the power of the fiber optic signal transmitted by the bridge, refer
to Figure 2–7 and follow these steps:
a. Connect the FDDI connector end of the receive cable to the FI port recep-
tacle on the bridge.
b. The other end of the receive cable has two leads (and fiber optic connec-
tors). The lead with the arrow pointing towards the connector carries the
transmit signal from the bridge. Plug this lead into the test head of the
meter.
