Stratum-3 Clock LED Strategy

Last Updated : Jul 06, 2015 |
Note:
When looking in the Stratum-3 cabinet, A card is on the left and B card is on the right.
The normal LED scheme is not followed for this device. Green LEDs do not indicate maintenance activity. There are no yellow LEDs, and there are more than three LEDs per circuit pack.
Removal of a card in the Stratum-3 clock may cause alarms to be resolved and the query test to pass. However, the removed cards should still be replaced to restore the Stratum-3 clock to full service.
The Stratum-3 clock has the following components:
  • 2 Clock Input cards (CI)
    Provides the logic to select the DS1 reference or Clock Input card. The red FAIL LED on this card indicates a failure with the card or the DS1 reference connected to it.
  • 2 Stratum-3 Cards (ST3)
    Provides 24-hour holdover. The red FAIL LED on this card indicates a failure with the card. Replace the card.
  • 2 Timing Output Cards (TOC)
    Provides cable length compensation, multiple output ports, selection of the ST3, and CI outputs. This type of card has two red failure LEDs: one indicates a failure of the card, the other indicates a failure in one or more output ports. In either case, replace the card.
  • 1 PBX (Private Branch Exchange) Alarm Interface (PAI)
    Filters power supplied to the clock, provides fuse protection, and provides alarm indications based on inputs supplied by other cards. The six LEDs on this card provide indications for the six alarm or status conditions as follows:
    • Loss of DS1 reference A
    • Loss of DS1 reference B
    • Loss of one clock unit
    • Loss of both clock units
    • Loss of one power supply
    • Loss of both power supplies
The output of the CI and PAI cards go directly to the TN780 Tone-Clock circuit pack via two 25-pair amphenol terminated cables. Every card has red and green LEDs for providing status or alarm indications. The abbreviations used in the table are defined above except for SRC (source) and Phase Locked Loop (PLL).
Stratum-3 Clock LED Indications of
Card
Name
Color
Indication
PAI
REF A
Red
Loss of input reference A or CI A failed
REF B
Red
Loss of input reference B or CI A failed
ST A
Red
Failed Stratum-3 clock A
ST B
Red
Failed Stratum-3 clock B
PWR A
Green
-48VDC A present
PWR B
Green
-48VDC B present
CI
FAIL
Red
Card failure
DS1
Green
DS1 source present
CC
Green
Composite clock source64 present
SRC ACTIVE
Green
Card is currently on-line
ST3
FAIL
Red
Card failure
LOCK
Red
PLL lost sync with reference or holdover mode
REF A
Red
Timing Reference from CI A
REF B
Red
Timing Reference from CI B
TOC
FAIL
Red
Card failure
PORT ALM
Red
Output port alarm (one or more)
ST
Green
Reference present from ST clock
INPUT
Green
Reference present from CI
500’
Green
500-foot phase advance
1000’
Green
1000-foot phase advance
64Composite Clock (CC) source refers to the protocol used to electrically transfer timing from the Stratum-3 clock to the switch. The Composite Clock source is not relevant to the system.