Apple Hard Drives Service Manual

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Hard Drives

SCSI Drives

IDE Drives

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Basics

Hard Drive

Basics

IDE Drives - 1

 

 

 

IDE Drives

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

 

 

 

WIDE and FAST SCSI Protocols

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.

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Troubleshooting

Hard Drive

Troubleshooting

General/ - 1

 

 

General

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

 

 

HD SC Setup

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.

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Upgrades

Hard Drives

Upgrades

Drives in Quadra 900/950 - 1

 

 

 

Hard Drive Carrier

Hard Drive Mechanism

SCSI Select

Cable

Termination

Resistors

SCSI Select

Switch

Drives in Quadra 900/950

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

Apple Hard Drives Service Manual

Upgrades Drives in Quadra 900/950 - 3

 

Tab

 

Removing Resistors

 

 

from the 160 MB

 

 

 

 

 

Tab

Hard Drive

SCSI

Terminator

 

 

Caution: Failure to remove

Select

Resistors

 

Cable

 

 

the terminator resistors can

 

 

 

damage the logic board.

 

 

 

1 Pull up on the tab and

 

 

 

remove the resistors

 

 

 

from a replacement

 

 

 

160 MB hard drive.

 

 

 

2 Insert the drive in the

 

 

 

customer’s carrier and

 

 

 

install four screws.

 

 

 

3 Attach the SCSI select

 

 

 

cable tab-up as shown.

Upgrades Drives in Quadra 900/950 - 4

SCSI Select

Removing Resistors

Cable

Tab

from the 230 MB

 

 

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.

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