Building a Wall Box for Tests A - C

To build a wall box to test for transmit/receive pair continuity and transmit/receive phasing, for test cases A through C, you need the following items:

•

Insertion tool

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two pieces of #22 AWG wire 8 cm (3 in.) long

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Two wall boxes

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One 1N4001 diode

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Two 47 cm (18 in.) patch cords

Modify the box as follows:

1.

Remove the cover of the wall box.

The wall labeling of the insulation displacement terminals on the PC board in the wall box may be either by number or color.

2.

Using the wire insertion tool, connect one of these 8 cm (3 in.) wires from Bk (#1, Tx+) to Y (#2, Tx-).

3.

Connect the other wire from R(#3, Rx+) to BU(#4, Rx-).

4.

With the insertion tool, connect the anode of a diode to BK (#1, Tx+) and the Cathode to R (#3, Rx+).

Tests A - C for Transmit/Receive Pair Continuity and Phasing

This section details the test procedure for Transmit/Receive Pair Continuity and Transmit/Receive Phasing testing, test cases A through C.

Follow the instructions below to perform the tests:

1.

Using one of the 47 cm (18 in.) patch cords, connect this modified wall box to the previously installed terminal end wall box of the line you wish to test.

2.

Connect a second wall box (with the cover removed and no wires connected to the insulation displacement terminals) directly to the RJ-45 terminated cable which plugs into the hub at the other end of the line you wish to test. The complete connection should look like that in Figure 3-16.

3.

Determine whether the installation is a 100 percent NCR-recommended Ethernet system or one that uses non-NCR wire and/or equipment. It is necessary to identify the type of Ethernet system since different system configurations have different allowable cable lengths.

With your ohmmeter in the ohm range, perform the appropriate test below:

Case A: Tests to measure the continuity in the transmit pair

Measure the resistance between the BK (#1) and Y (#2) terminals at the wall box at the end of the line you are testing.

The resistance levels should be in the range of the table shown in Figure 3-19. Refer to Figure 3-17 for arrangement of wall boxes and ohm meter probes.

Case B: Tests to measure the continuity in the receive pair

Measure the resistance between the R (#3) and BU (#4) at the wall box t the end of the line you are testing.

The resistance values should be in the range of the table shown in Figure 3-19. Refer to Figure 3-17 for the arrangement of wall boxes and ohmmeter probes.

Case C: Test the phasing between transmit pair and receive pair

At the wall box from which you are testing, measure the resistance between BK (#1) and R (#3) with the positive meter probe on the BK terminal. Use the meter to look for the low forward resistance of the diode with this polarity. If a high resistance is observed, the lines are reversed or there is an open line. Resistance level guidelines are not valid when measuring a diode.

Wire Type	Maximum Cable Length	Max Resistance Per Conductor of 304.8 m (1000 ft) of Cable	Max Resistance (for Maximum Cable Length)
AT&T 1061	100 m (328.1 ft)	28.6 ohms	18.76 ohms
AT&T 1010	50 m (164.0 ft)	28.6 ohms	9.38 ohms
Other 50 m	(164.0 ft)	28.6 ohms	9.38 ohms