Section 363-752-100
Revision 01
Page 6
TABLE 3. FRC-752 CHANNEL UNIT TROUBLESHOOTING
Indication
Problem
Action
FAULT
LED on
The processor in
the RT Line Unit
has stopped.
Remove and replace the RT Line Unit. If the system does not restart, replace the RT Line Unit.
Troubleshooting based on customer-originated trouble reports
No
Dialtone,
Can’t Dial
Short circuit,
faulty COT, or
faulty RT
Channel Unit.
1. Lift the subscriber pair at the RT. If dialtone is present at the RT and calls can be placed,
check for shorts toward the subscriber or on the customer’s premises.
2. If you cannot hear a dialtone and/or cannot make calls at the RT with the subscriber drop
lifted, lift the jumper in the CO between the CO switch and the COT. If you hear a dialtone
and/or can make calls at the switch, replace the COT Channel Unit and/or RT Channel Unit.
Otherwise, the problem is in the CO switch.
Phone
Doesn’t
Ring
High-resistance
short on
subscriber drop,
faulty RT
Channel Unit, or
faulty RT Line
Unit.
1. Check for ringing at the RT. If ringing isn’t present on the line under test, try ringing
another line terminated on the same RT Channel Unit. If ringing is present on other lines,
check for high resistance shorts on the subscriber drop.
2. If ringing isn’t present on a circuit terminated on the same RT Channel Unit, try ringing a
line terminated on another RT Channel Unit. If the line rings, replace the RT Channel Unit. If
the line doesn’t ring, replace the RT Line Unit.
Phone
Doesn’t Stop
Ringing
Faulty subscriber
station instrument,
faulty RT Channel
Unit, or loop length
too long.
Phone stops ringing when using a butt-in at subscriber location:
Subscriber’s station instrument’s internal resistance is too high. Replace instrument according
to local policies.
If phone doesn’t stop ringing when using a butt-in at the subscriber location, re-test at the RT:
If phone still doesn’t stop ringing, replace the RT Channel Unit.
Otherwise, loop length between RT and subscriber is too long.
Can’t Hear,
Can’t Be
Heard
Subscriber
problem, faulty
COT Channel Unit,
or faulty RT
Channel Unit.
1. Lift the subscriber drop at the RT. If audible level is acceptable, there is a problem toward
the subscriber.
2. If audible level is too low at the RT with the subscriber drop lifted, lift the jumper in the
CO between the CO switch and the COT. If audible level is acceptable, replace the COT
Channel Unit and/or RT Channel Unit. Otherwise, the problem is in the CO switch.
Copyright © 1996, PairGain Technologies, Inc. PairGain is a registered trademark, CopperOptics and HiGain are trademarks of
PairGain Technologies, Inc.
