AT&T System 25 - Manual (Page 242)

MAINTENANCE
Table 4-C. Circuit Pack Voltage–Symptoms
Voltage/ +5 volts -5 volts -48 Volts
Circuit Pack (Notes) No+5 V No-5 V No-48 V
Call Proc. (ZTN82,
x
System Failure
x
EIA Failure x ETU Activated
ZTN1 28) for RI
Memory (ZTN81, x System Failure - - - -
ZTN1 27) for RI
CPU/Memory (ZTN129, x System Failure x EIA Failure
x
ETU Activated
for R2, ZTN130
for R3)
STARLAN (ZTN84) x CP Failure
x
CP Failure - -
Service Ckt (ZTN85 x System Failure - - - -
or ZTN131 (R3)
Hybrid Line (ZTN79) x CP Failure x No Voice x Station OS
Tip/Ring (ZTN78)
x
CP Failure
x
No Voice x Station OS
Analog Line (TN742) x CP Failure x No Voice x Station OS
MET Line (TN735)
x
CP Failure x No Voice x Station OS
Loop Start (ZTN77) x CP Failure x No Voice x Trunks OS
Grd Start (ZTN76) x CP Failure x No Voice x Trunks OS
DID Trk (TN753) x CP Failure x No Voice x Trunks OS
Tie Trk (TN760B) x CP Failure x No Voice x Trunks OS
Aux Trk (TN763) x CP Failure x No Voice x A
UX
. Eq. OS
Data Line (TN726) x CP Failure - - - -
Tone Det (TN748) x Tone Failure - - - -
Legend:
Notes: 1
CP—Circuit Pack
ETU—Emergency Transfer Unit
OS-Out-of-Service
X—indicates that the voltage is used by the associated CP.
.Ringing voltage (not shown on table) is used by the ZTN78 and TN742
CPs. Associated stations will not ring if a ringing voltage problem occurs.
2. TN746B same as TN742
3. TN747 same as ZTN76 and ZTN77
4. TN762 same as ZTN79.
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