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CHAPTER 5 NDA-24300
Page 340
Issue 1
FAULT REPAIR PROCEDURES
4.3 Unit Fault - When Dial Tone (DT) Cannot Be Heard
Faulty Situation:
• Dial Tone (DT) cannot be heard except within a unit.
• [4-T] Both MUX Failure / [4-S] MUX Ready Failure
• [23-Y] MUX Clock Failure
Note:
For dual system configuration, if a system message indicates that both systems are faulty, first repair
the fault in the indicated system and then proceed to repair the PIM in the other system.
(1) For Dual Configuration
Check to see if the MUX (PH-PC36) circuit
card is making poor contact.
Set the MUX circuit card into STBY mode by
flipping the MBR key on the active GT (PH-
GT09) card. Refer to Section 12.1.6, Manual
System Changeover of Speech Path System, in
Chapter 6.
Set the MB switch of the MUX circuit card UP.
Extract the MUX circuit card from its mounting
slot and clean the contact portion.
If cleaning cannot be done, repeat insertion and
extraction of the circuit card two or three times.
Set the MB switch of the MUX circuit card UP
and insert the circuit card into its mounting slot.
Set the MB switch of the MUX circuit card
DOWN.
Check to see if a station-to-station connection
can be set up within the faulty unit.
Check by replacing the MUX circuit card
with a spare.
Place the MUX circuit card into STBY mode by
flipping the MBR key on the active GT (PH-
GT09) card. Refer to Section 12.1.6, Manual
System Changeover of Speech Path System, in
Chapter 6.
Replace the MUX circuit card. Refer to Section
3.3.2, MUX Card Replacement Procedure, in
Chapter 4.
ATTENTION
Contents
Static Sensitive
Handling
Precautions Required
START
A
B