Digital Equipment DECmpp 12000/Sx 100, Руководство по обслуживанию оборудования, Страница: 56 / 156

6.3 Replacing DPU Card Cage PCBs
6.3 Replacing DPU Card Cage PCBs
Warning
To avoid personal injury or damage to equipment, make sure the system
is turned off before replacing or adding any PC PCBs. 5 V power supplies
deliver current in the 600 A range.
Proper antistatic protection must be worn while servicing the DPU.
To avoid damage, always handle a PCB correctly:
• Wear antistatic equipment (for instance, a wrist or ankle strap) when
handling a PCB.
• If working on a PCB, use a static-free work surface.
• Handle it gently by the edges.
• Never handle a PCB by the component or etched surfaces.
• Store PCBs in a static-proof container.
Each PCB in the DPU card cage has ejector levers on the top and bottom of
the PCB faceplate, shown in Figure 6–4. Always use the ejector levers when
removing or replacing PCBs:
• To release the PCB, lift up the lower end of the top lever, and press down on
the upper end of the bottom lever, moving the PCB partway out of its slot.
• To secure the PCB in the card cage slot, press down the lower end of the top
lever and the upper end of the bottom lever.
6.3.1 Replacing the Array Control Unit PCB
Caution
Make sure that you are grounded through a wrist or ankle strap before
handling the ACU.
The ACU PCB is in the first I/O slot (labeled ACU) in the DPU card cage. To
replace the ACU PCB, take the following the steps.
1. Turn off the system, as described in Chapter 1.
2. Open the DPU rear door.
3. Loosen the captive screws on the top and bottom of PCB faceplate.
4. Remove the top PCB retainer bar.
5. Use the ejector levers shown in Figure 6–4 to release the PCB and move it
outward from its slot.
6. Carefully remove the PCB from its slot, handling it by the edges, and place it
in a static-proof container.
7. Verify the jumper configuration on the new ACU PCB (Table 6–1).
8. Carefully slide the replacement PCB into the slot.
6–6 Removal and Replacement Procedures