PictureTel III ISA - Manual (Page 77)

Diagnostic Testing Under Windows 3.x 6-3
Follow these steps to run the Group 1 tests:
1 From the Test menu, select Run Tests and press Enter.
The Run Tests dialog box appears with the Start button
already selected.
2 Press Enter to start the tests.
Group 1 tests run 10 times (default setting) unless you specify
otherwise. The test results are displayed in the Results column.
Running the Group 2 Test
The Group 2 test is the Network Loopback Test. It tests whether
the 3C509B-COMBO and 3C509B-TPC NICs can transmit and
receive data over thin Ethernet coaxial wire. This test requires
either installing a loopback plug at the transceiver connection
on the NIC or running the test on an idle network.
A failure in this test usually indicates a cabling problem.
CAUTION: Running the Group 2 test while connected to an active
network can cause intermittent failures.
Assembling a Loopback Plug
If you do not have a loopback plug, you can order one from your
authorized network supplier or you can make your own. You can
purchase the terminators from your network supplier (3Com part
number 3C535).
To assemble the loopback plug, connect two 50-ohm network
cable terminators to a T connector, as shown in
Figure 6-1 .
Figure 6-1 Assembling a Loopback Plug
50 Ω Terminator
50 Ω Terminator
T connector