7-4 Dell PowerEdge 4200 Systems Installation and Troubleshooting GuideFigure 7-3. Removing the Front BezelInside the ChassisIn Figures 7-4 and 7-5 the computer covers are removedto provide interior views from the left and right sides.These illustrations also identify features on the front andback of the computer. Refer to these illustrations to locateinterior features and components discussed later in thisguide.When you look inside the computer, note the direct current(DC) power cables leading from the power supply oroptional power supply paralleling board. These cablessupply power to the system board, small computer sys-tem interface (SCSI) backplane board, externallyaccessible drives, and certain expansion cards that con-nect to external peripherals.The flat ribbon cables are the interface cables for internaldrives. For non-SCSI drives, an interface cable connectseach drive to an interface connector on the system boardor on an expansion card. For SCSI devices, two interfacecables connect externally accessible SCSI devices andthe SCSI backplane board to a SCSI host adapter eitheron the system board or on an expansion card. If youattach external SCSI devices, such as a SCSI tape driveor SCSI scanner, use the upper SCSI connector slot forthe SCSI cable. If you attach a Dell PowerEdge ScalableDisk System 100 (SDS 100), use the SCSI connector onthe back of the expansion card for the SCSI cable and theSMB connector for the SMB cable.The system board—the large, vertical, printed circuitboard at the left side of the chassis near the back—holdsthe computer’s control circuitry and other electroniccomponents. Some hardware options are installeddirectly on the system board. The system board provideseight expansion-card connectors. The external drive baysprovide space for up to four half-height drives, typicallydiskette drives, CD-ROM drives, or tape drives. Theinternal drive bays provide space for up to six half-heightSCSI hard-disk drives. These drives are connected to theSCSI host adapter via the SCSI backplane board, whichmanages the drive bays and monitors the drive environ-ment, including voltages and temperatures.During an installation or troubleshooting procedure, youmay be required to change a jumper or switch setting on thesystem board, an expansion card, or a drive. For informa-tion on the system board jumpers, see Appendix C,“Jumpers and Switches.”tabs (4)
