Vodavi Starplus DHS, Technical Manual

Page: 296 / 338

CPU/Power LED 7-3
Table 7-2: Key Telephone / SLT Telephones Dead
SYMPTOM
DIAGNOSTIC
AID
CAUSE CORRECTIVE ACTION
Telephones/station
apparatus dead. CPU Heartbeat /
Power LED Lit Shorted Station
Pair(s)
1. At MDF, remove cross connect (jumper)
wires at the punch-down (66M1-50) block
going to all affected stations.
2 Reconnect stations one by one verifying
that each power up correctly.
Key Telephone Bad Key
Telephone When one is found that will not power up:
1. Disconnect the telephone at the user
location.
2 replace with a known working telephone.
† If the new station power up is normal,
replace the first connected key telephone.
† If the new station also does not power up,
follow the remaining steps for the
individual station.
† If none power up; remove all cross connect
wiring that run between the 3x8 Module
66 block and the station cable 66 block.
3 Connect one station directly to the 3x8
Module 66 block station pair.
Shorted station
cable If the key telephone power up is normal:
inspect, repair or replace the station cable.
Shorted KSU-MDF
cable If the key telephone does not power up:
inspect, repair or replace the 25 pair cable
from the 3x8 Module to the MDF.
Once the 25 pair cable from the 3x8 Module to
the MDF is inspected, repaired or replaced;
connect the
known working telephone directly
to the 3x8 Module 66 block station pair.
3x8 Module
ribbon cable not
properly aligned
during installation If the telephone still will not properly power
up, power down the system and inspect the
3x8 Module ribbon cable for properly aligned
installation. If any problem exists here correct
it and power up the system.
3x8 Module bad If no problems can be found at the ribbon
cable connector, replace the 3x8 Module.
CPU Module bad If the problem persists, replace the KSU.
The key telephones use only one twisted cable pair for power, data control and voice
communications. There are no fuses for station interface protection. Instead, a current sensing
poly-switch limits excessive current going to each station. If a station cable pair is shorted or a
telephone’s DC power supply is damaged, the poly-switch will temporarily open to protect the
KSU 3x8 Module circuitry.