K Service Source
SCSI Drives
IDE Drives
K Service Source
Hard Drive
Basics |
IDE Drives - 1 |
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Intelligent drive electronics, IDE, incorporates controller hardware into the drive. IDE is offered in 8- and 16-bit interface types. Eight-bit drives are sometimes referred to as XT interface drives, and 16-bit drives are sometimes referred to as AT interface drives.
IDE drives do not use a SCSI bus. Apple computers continue to use an external SCSI chain, which is supported by a SCSI chip on the logic board.
Also, Apple’s HD SC Setup works with IDE drives.
Basics |
WIDE and FAST SCSI Protocols - 2 |
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SCSI chains that use SCSI-2 protocols are faster than SCSI chains using the original SCSI protocols. Two terms used in the SCSI-2 protocol are “WIDE” and “FAST.”
The term “WIDE” defines the 2-byte or 4-byte wide data interface where each data byte uses its corresponding parity bit. The traditional SCSI-1 interface protocol is 1 byte wide. “FAST” SCSI is defined as data transfer rates between 5 MHz and 10 MHz.
Check these protocols against individual drives for comparative data.
Devices using the SCSI-2 WIDE and FAST protocols are compatible with existing SCSI-1 devices.
K Service Source
Hard Drive
Troubleshooting |
General/ - 1 |
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The Symptom Charts included in this chapter will help you diagnose specific symptoms related to your product. Because cures are listed on the charts in the order of most likely solution, try the first cure first. Verify whether or not the product continues to exhibit the symptom. If the symptom persists, try the next cure. (Note: If you have replaced a module, reinstall the original module before you proceed to the next cure.)
If you are not sure what the problem is, or if the Symptom Charts do not resolve the problem, refer to the Flowchart for the product family.
For additional assistance, contact Apple Technical Support.
Troubleshooting |
HD SC Setup/ - 2 |
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Before you replace any drive hardware, run HD SC Setup to update the driver on the drive.
HD SC Setup works with SCSI and IDE drives.
K Service Source
Hard Drives
Upgrades |
Drives in Quadra 900/950 - 1 |
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Hard Drive Carrier
Hard Drive Mechanism
SCSI Select
Cable
Termination
Resistors
SCSI Select
Switch
There are three general procedures for preparing hard drives for Quadra 900/ 950 computers:
• Removing the hard drive mechanism from the carrier.
• Removing resistors from the replacement drives.
• Connecting the SCSI
select cable.
Upgrades
SCSI
Select
Cable
Drive Carrier
Drives in Quadra 900/950 - 2
Removing the Hard
Drive
1Disconnect the SCSI select cable from the hard drive.
2Remove the four Phillips screws.
3Slide the drive out of the carrier.
Hard Drive
Upgrades Drives in Quadra 900/950 - 3
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Tab |
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Removing Resistors |
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from the 160 MB |
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Tab |
Hard Drive |
SCSI |
Terminator |
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Caution: Failure to remove |
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Select |
Resistors |
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Cable |
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the terminator resistors can |
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damage the logic board. |
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1 Pull up on the tab and |
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remove the resistors |
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from a replacement |
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160 MB hard drive. |
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2 Insert the drive in the |
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customer’s carrier and |
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install four screws. |
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3 Attach the SCSI select |
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cable tab-up as shown. |
Upgrades Drives in Quadra 900/950 - 4
SCSI Select |
Removing Resistors |
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Cable |
Tab |
from the 230 MB |
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Hard Drive
Hard Drive
Terminator
Resistors
Caution: Failure to remove the terminator resistors can damage the logic board.
1Using needlenose pliers, remove the resistors from a replacement 230 MB drive.
2Insert the drive in the customer’s carrier and install four screws.
3Attach the SCSI select cable as shown.