Replace Clock Controller on 81c 1

[Norstarguy]

Hello all-

I was wondering if anyone can give me a step by step on replacing the clock controller cards (have two showing aging errors that won't clear even after disable & reseat) Trying to help someone out...

I'm sure we can make it thru, but would love to have a check list since we'll be doing it before the crack of dawn and would prefer to not blow anything up.

 

[Reusser]

Whats the Part number on the card - QPC471 or NTRB53

 

[Norstarguy]

Oops, sorry- QPC471H.

 

[Reusser]

Removing the CC card
1 The clock controller card must be on the inactive CPU. To switch the
active CPU:
LD 135
SCPU
****
2 Disable the clock controller card:
— The card being removed must be inactive:
LD 60
— In a single-CPU system:
DANGER
Module covers are not hinged; do not let go of the
cover. Lift the cover away from the module and set it
out of the work area.
Disable the clock controller card.
DIS CC x “x” is the card number—0 or 1
Check the status of the clock controller card you are removing.
SSCK x “x” is the card number—0 or 1
If the clock is active, switch clocks.
SWCK Switch system clock from active to standby
Make sure the card being removed is disabled and the other clock
controller card is active and in free run mode.
SSCK x
TRCK FRUN
Disable the clock controller card being removed.
DIS CC x “x” is the card number—0 or 1

3 Set the ENB/DIS switch to DIS on the card being removed.
4 Tag and disconnect cables to the card being removed.
5 Unhook the locking devices on the card and pull the card out of the card
cage.

Installing the CC card
1 Set the ENB/DIS switch to DIS on the replacement card.
2 Set option switches on the replacement card.
If there is a vintage change, be sure to check Circuit Card: Description
and Installation (553-3001-211) for any differences.
3 Insert the replacement card into the vacated slot and hook the locking
devices.
4 Connect cables to the replacement card.
5 Set the ENB/DIS switch to ENB on the replacement card.
6 Software-enable the card:
ENL CC x
Note: With a vintage H clock controller card, do not issue the tracking
(TRCK) or status (SSCK) commands at this time. If these commands are
used, the system may respond with an inaccurate error condition.
— In a single-CPU system, complete the replacement procedure
by exiting LD 60:
****
— In a dual-CPU system proceed with the following steps.
7 Switch CPUs:
LD 135
SCPU
****
8 Activate the newly-installed card and verify that it is active:
LD 60
SWCK
SSCK x
9 If applicable, issue a tracking command:
TRCK aaa “aaa” is PCK for track primary clock, SCLK for
track secondary clock, or FRUN for free run mode
Note: Configure the clock source to the status it was in before the
replacement procedure.
10 Verify clock switch-over and tracking:
SWCK
SSCK x
**** exit LD 60
11 Tag defective equipment with a description of the problem and package it
for return to a repair center.

 

[Norstarguy]

Thanks for the info! Star for you.

The only concern I have at this point is I've been told by a couple of other techs that they wouldn't do this procedure without splitting the cores first, followed with a sync/join for each after each card is replaced...

Thoughts?

 

[Reusser]

no need to split cores as clock is not a core card. Important thing is to always have one card active. Once you replace one card, enable and swap and make sure tracking before disabling or removing other clock.

Also make sure clock reference cables are correct.

 

[Norstarguy]

Thanks for the follow up answer. Did take care of this this AM, went without a hitch! Thanks for the help.