Toshiba DK8, DK 16 manual Fault Isolation Flow Charts

1)Disconnect the digital or electronic telephone.

2)Using a DC voltmeter, measure between the wires of the two pairs to verify the readings shown in Table B for electronic telephone ports (PEKU or PESU). Refer to Table D for digital telephone ports. The reading will be a plus or minus depending on meter lead place- ment.

3)An improper reading indicates an open, crossed or shorted wire.

4)For the MDF-to-telephone (digital or elec- tronic) cable, a more precise check is made using an ohmmeter.

8.10Ohmmeter Test

8.11The continuity of the cable run between the KSU and digital or electronic telephone is checked with an ohmmeter as follows:

1)Disconnect the electronic or digital tele- phone.

2)At the MDF, remove the bridging clips.

3)At the MDF, place shorting jumper wires between the T and R of pair #1 (green-red), the T and R of pair #2 (black-yellow) and the T and R of OCA pair #3 (blue-white), for PEKU/PESU only. (For MDF pin numbers, see Section 100-816-208.)

4)At the modular block, measure the resis- tance between all wire combinations. The proper readings are shown in Table C for electronic telephones and HDSSs, and Table E for digital telephones, DDSSs and DDCBs.

8.20Cable Installation

8.21If cable voltmeter and ohmmeter tests are within limits, digital telephones may not operate because of the following:

1)Digital telephone cable runs must be free of cable splits (single or double). Test for and

FAULT FINDING

SECTION 100-816-500

MARCH 1993

eliminate all cable splits.

2)Cable bridge taps – Digital telephones will not operate if cable runs contain any type (short or long) of cable bridge. Test for and eliminate all cable bridges.

3)When installing the station cable, do not run parallel to and within 3 feet of an AC power

line. AC power lines should be crossed at right (90°) angles only. In particular, avoid running station wire pairs near devices that generate electrical noise, such as neon or fluorescent light fixtures.

4)Check Table 8-D, in Section 100-816-208. Verify that your telephone is wired correctly (2-pair or External power) for the options it supports (ADM, PDIU-DI, HHEU, DVSU, etc.).

9 FAULT ISOLATION FLOW CHARTS

9.01The following troubleshooting flow charts are available to aid in fault isolation. It is recommended to read paragraph 1~5 of this section and then proceed to CHART 1, page 7, to begin fault isola- tion.

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