Troubleshooting and Repair 4-19When disassembling the system unit, follow these general rules.n Disconnect all peripherals.n When handling boards or chips, touch the system unit frame to discharge static.n Do not disassemble parts other than those specified in the procedure.n All screws are Phillips-head, unless otherwise specified.n Label all removed connectors. Note where the connector goes and in whatposition it was installed.On completion of any reassembly, perform a power-on test (see “Check” in Section 2). If afault occurs, verify that the reassembly was performed correctly.CAUTION: When handling boards or chips,ground yourself to release static.Top Cover RemovalRemove the top cover as follows.NOTE: Unplug the power cord beforedisassembling the system unit. Voltage is presentinside the system unit even after the power is off.All voltage is removed only when the powercord is unplugged.1. Power off and unplug the keyboard, mouse, power and all other peripheral cablesattached to the system unit.2. Unlock the system unit top cover if locked.3. Remove the four cover screws shown in Figure Section 4-3.
