910 NTAK20 Clock Controller daughterboardState DefinitionOn (Green) NTAK20 is equipped, enabled, and is either locked to a reference or is in free runmode.Flashing(Green)NTAK20 is equipped and is attempting to lock (tracking mode) to a reference. If theLED flashes continuously over an extended period of time, check the CC STAT inLD60. If the CC is tracking this may be an acceptable state. Check for slips andrelated clock controller error conditions. If none exist, then this state is acceptable,and the flashing is identifying jitter on the reference.Off NTAK20 is not equipped.Each motherboard has five DTI/PRI LEDs and one clock controller LED.The clock controller LED is dual-color (red and green). The clock controllerLED states are described in Table 372 "Faceplate LEDs" (page 910).Table 372Faceplate LEDsState DefinitionOn (Red) NTAK20 is equipped and disabled.On (Green) NTAK20 is equipped, enabled, and is either locked to areference or is in free run mode.Flashing(Green)NTAK20 is equipped and is attempting to lock (tracking mode) toa reference. If the LED flashes continuously over an extendedperiod of time, check the CC STAT in LD 60. If the CC is trackingthis may be an acceptable state. Check for slips and relatedclock controller error conditions. If none exist, then this state isacceptable, and the flashing is identifying jitter on the reference.Off NTAK20 is not equipped.Functional descriptionThe main functional blocks of the NTAK20 architecture include:• phase difference detector circuit• digital Phase Locked Loop (PLL)• clock detection circuit• digital-to-analog converter• CPU MUX bus interface• signal conditioning drivers and buffers• sanity timer• microprocessor• CPU interfaceNortel Communication Server 1000Circuit Card ReferenceNN43001-311 01.04 StandardRelease 5.0 23 May 2008Copyright © 2003-2008, Nortel Networks.
