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5.2 Fault in Specific Station Only
Find the cause according to the following table if the fault lies with a specific
station only, not with all stations.
SYMPTOM
Dialing can not be
made at privacy off
mode.
Specific key does not
operate.
Calling tone can
not be heard.
Sound from the
other party can not
be heard.
Sound is not trans-
mitted to the other
party.
On dialing, noise is
heard by the called
party.
Sound of the other
party is broken during
call.
Immediately after the
calling tone, the line
switches to cancel,
busy, dial tone, etc.
CHECK-ITEM
Replace the
station and make
sure that the
station is not
faulty.
Replace the
station and make
sure that the
station is not
faulty.
Same symptom
remains even if
the station is
replaced.
Becomes normal
if the station is
replaced.
Same symptom
remains even if
the station is
replaced.
Becomes normal
if the station is
replaced.
Same symptom
remains even if
the station is
replaced.
Becomes normal
if the station is
replaced.
Same symptom
remains even if
the station is
replaced.
Same symptom
remains even if
the station is
replaced.
Becomes normal
if the station is
replaced.
CAUSE
* Disconnection of both T & R Lines.
* T & R Lines are shorted.
* Fault in key board switch or matrix circuitry.
* Fault in the dial generator. (Replace PCB
board.)
* Short or open in R Line.
* Fault in LAU.
* Disconnection of R Line or improper connec-
tion of the station connector.
* Fault in LAU.
* Station fault.
* Short or open in T Line.
* Fault in LAU.
* Fault in MIC circuitry of the station. (Replace
MIC or
PCB.)
* One of T Lines is disconnected.
* Fault in LAU.
* Fault in MIC element.
* Fault in T Line of the station.
* Low-frequency oscillation of MIC AMP.
(Faulty bypass capacitor.)
* Adjust the volume control of station speaker
if the room produces reverberation. (Lower
the volume.)
* Increase the gain of MIC AMP.
* Replace PCB after checking if MIC unit is not
touching its case.
* One of R Lines is disconnected.
* Fault in LAU.
* Station fault.
* One of the R Lines is disconnected or the
station connector is not connected properly.
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