Sun Microsystems 6.0005E+11 - Manual (Page 126)

6-2 Ultra Enterprise 6000/5000/4000 Systems Manual—November 1996
6
6.1 Handling Boards and Assemblies
Caution – The chassis AC power cord must remain connected to ensure a
proper ground.
Caution – The clock board and its modules have surface-mount components
that can be broken by flexing the board.
To minimize the amount of board flexing, observe the following precautions:
•
Hold the board only by the edges near the middle of the board, where the
board stiffener is located. Do not hold the board only at the ends.
•
When removing the board from an antistatic bag, keep the board vertical
until you lay it on the Sun ESD mat.
•
Do not place the board on a hard surface. Use a cushioned antistatic mat.
The board connectors and components have very thin pins that bend easily.
• Do not use an oscilloscope probe on the components. The soldered pins are
easily damaged or shorted by the probe point.
•
Transport the board in an antistatic bag.
• Be careful not to drag boards across surfaces as board components are easily
damaged.
6.2 Clock Board
There is one clock board to a system. The clock board provides:
•
Programmable system and processor clock
•
Serial, keyboard, and mouse ports for the console
• Centralized Time-of-day (TOD) chip that includes NVRAM
•
Centralized reset logic
•
Status and control of power supplies
The clock board consists of the following subsystems:
•
Console Bus
•
Clocks
•
Reset logic
•
JTAG
•
Centerplane connector signals
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