Apple Power Macintosh G3 User Manual

Service Source

Power Macintosh G3

Desktop

Service Source

Hot Issues

Power Macintosh G3 Desktop

Hot Issues Introduction - 1

Introduction

This chapter is designed to highlight unique or highpriority product issues that you should be aware of before servicing the Power Macintosh G3 Desktop computer.

This chapter alerts you to important issues and provides links to other areas in the manual where more complete information can be found. This chapter is not intended to replace other parts of this manual; it merely provides a pointer to pertinent information in those chapters.

To familiarize yourself with a new product family, always read the Basics chapter in its entirety.

Hot Issues Shared Logic Board - 2

Shared Logic Board

The Power Macintosh G3 Desktop and Minitower computers use the same logic board, but there are jumper settings that differ between them (see “Jumper Location J28” and “Jumper Location J16” in the Troubleshooting chapter).

Processor Module Vs. Card

Whereas previous Power Macintosh computers featured a user-installable processor card, this logic board uses a processor module that must not be removed by the customer (see “Processor Module” in the Take-Apart chapter).

Hot Issues Power Supply Jumper - 3

Power Supply Jumper

The Power Macintosh G3 Desktop logic board has a power supply jumper, which is installed at J28. The setting of this jumper differs between the Power Mac G3 Desktop and Minitower. Failure to install this jumper in the correct position may result in a computer that won’t boot up. (See “Jumper Location J28” in the Troubleshooting chapter.)

Processor Module Jumper

The Power Macintosh G3 Desktop logic board has a processor module jumper, which is installed at J16. The processor jumper is color coded for the speed of processor module used. Failure to install the correct jumper may result in a computer that won’t boot up. (See “Jumper Location J16” in the Troubleshooting chapter.)

Hot Issues Warranty Sticker - 4

Warranty Sticker

There is a warranty sticker that covers the processor module jumper. The customer’s warranty is void if this sticker is tampered with. Service Providers must replace this sticker if they have removed it during servicing to protect the customer’s warranty. (See “Processor Module” in the Take-Apart chapter.)

Power Supply Voltage Setting

There is a switch on the back of the power supply that controls the voltage setting. The voltage switch correctly to avoid damaging the computer. (See “Voltage Switch” in the Basics chapter for more information, including an international voltage chart.)

must

be set

Hot Issues Voltage Regulator - 5

Voltage Regulator

There is a removable voltage regulator on the logic board, which comes with the logic board and can also be ordered as a separate module. (See “Voltage Regulator” in the Troubleshooting chapter.)

I/O Card

Some I/O functions on the logic board are handled through a removable I/O card that must be installed for the computer to operate properly. (See “I/O Cards” in the Troubleshooting chapter.)

Hot Issues ROM DIMM - 6

ROM DIMM

The Power Macintosh G3 Desktop logic board uses a ROM DIMM as opposed to soldered ROM. You should not remove the ROM DIMM from the logic board. (See “Logic Board” in the Take-Apart chapter for instructions on how to prepare the logic board for return to Apple Computer.)

SDRAM DIMMs

The Power Macintosh G3 Desktop uses SDRAM DIMMs. DIMMs from older Macintosh computers, although they will fit, are not compatible and should never be used in the Power Macintosh G3 computers. (See “SDRAM DIMMs” in the Basics chapter and refer to the Power Macintosh G3 Desktop section of the Memory Guide.)

Hot Issues SGRAM Video Memory - 7

SGRAM Video Memory

Power Macintosh G3 computers use SGRAM video memory. Use only SGRAM SO-DIMMs in these machines. Never install the 256K or 512K video memory DIMMs used in older Macintosh computers. (See “SGRAM Video Memory” in the Basics chapter.)

EIDE Bus Issue

If you have only one device connected to the EIDE bus, the device must be plugged into the first EIDE connector on the logic board (the one closer to the rear panel), which is marked J9. If you plug the device into J10 and leave J9 empty, the device may not boot up. (See “Connecting EIDE Devices to the Logic Board” in the Basics chapter.)

Hot Issues Master/Slave Support - 8

Master/Slave Support

Some Power Macintosh G3 Desktop computers support adding two ATA/IDE devices to the same ATA/IDE channel, or what is commonly known as master and slave. This configuration provides user with the ability to add additional hard drives or removal media devices to their system. Because the cabling is different, you cannot replace ATA drives with SCSI drives and vice versa. (See “Support for Master and Slave” in the Basics chapter.)

Ultra Wide SCSI Cable Routing

The Ultra Wide SCSI cable (if present) must be routed inside the computer’s chassis in a very specific manner. Failure to route the cable correctly could result in performance problems. (See “Ultra Wide SCSI PCI Card” in

Hot Issues DVD-ROM Disk Damage - 9

the Take-Apart chapter.)

DVD-ROM Disk Damage

The Power Macintosh G3 Desktop offers DVD-ROM drives as a build-to-order option. It is important to note that DVD disks are much more prone to damage than CD-ROM disks. Any type of scratch or other abuse may result in a disk that is unreadable. (See “DVD-ROM Drive Technology” in the Basics chapter.)

CD-ROM Ejection Problem

If you have a CD-ROM drive in a Power Mac G3 Desktop that fails to eject CDs properly, you may need to install poron bumpers. (See “CD-ROM Drive” in Troubleshooting.)

Hot Issues HFS+ Formatted Drives - 10

HFS+ Formatted Drives

Hard drives that ship with the Version 2 Power Macintosh G3 logic board (part number 661-2063) use a file format called Mac OS Extended format, also referred to as HFS+. Norton Utilities version 3.5 is not compatible with Mac OS and version 3.5.1 and earlier can result in hard drive corruption and loss of all data on the hard drive. If you experience problems with a hard drive in one of these systems, Apple Computer recommends using the version of Disk First Aid included on the system software CD that shipped with the unit. (See “HFS+ Formatted Drives” in the Troubleshooting chapter.)

Hot Issues Power-On Issue - 11

Power-On Issue

If you experience a power-on issue with the Power Macintosh G3 Desktop where the power supply fan is spinning, but there is no boot tone, no hard drive noise, no power LED, and no video, you may have an improperly installed or faulty voltage regulator. You should always reseat and/or replace the voltage regulator before replacing the logic board. (See “System” symptom/cures in the Troubleshooting chapter.)

Service Source

Basics

Power Macintosh G3 Desktop

Basics Overview - 1

Overview

The Power Macintosh G3 desktop chassis design allows you to access the logic board and its components, including the removable processor, without having to remove the power supply or any drives. This flexible design makes this computer easy to service and upgrade.

The Power Macintosh G3 desktop has a unique PERCH slot that accepts an I/O card that provides audio capabilities of the computer.

Basics Overview - 2

Features of the Power Mac G3 Desktop include:

• PowerPC G3 microprocessor running at 233 MHz, 266 MHz, or 300 MHz

• RAM expandable to 384 MB in 3 DIMM card slots using 64-bit 168-pin JEDEC-standard 3.3 V unbuffered SDRAM DIMM cards (Note: to expand to the maximum capacity of 384 MB requires low-profile DIMMs with maximum height of 1.15”. Using higher-profile DIMMs with a height of 1.25”, the maximum SDRAM capacity is 192 MB.)

• 512K backside L2 cache (233 or 266 MHz) or 1 MB backside L2 cache (300 MHz) on processor module

• Built-in 2D and 3D hardware graphics acceleration

• PERCH slot to support I/O card

• One modem slot on the I/O card for optional fax/modem card

• 4 GB or 6 GB ATA hard drive(s)

Basics Overview - 3

• Three expansion bays for adding internal 3.5-inch SCSI devices

• Optional 100 MB SCSI Iomega or ATAPI Zip drive in one of the expansion bays

• CD-ROM ATAPI drive at 24X speed (unless customer orders DVD-ROM drive)

• 1.4 MB SuperDrive

• One SCSI port

• Two GeoPort serial ports

• 10BASE-T Ethernet port

• One ADB port

• Three PCI expansion slots to accept

• three 7-inch or 12-inch PCI cards, or

• three 15 W cards, or

• two 25 W cards

• Voltage switch

• Fan speed thermally controlled

• Energy Saver control panel

Basics Overview - 4

• 2 MB video RAM expandable to 4 MB or 6 MB with

3.3 V, 83 MHz or faster SGRAM on a 144-pin small outline dual inline memory module (SO-DIMM)

Optional Build-to-Order Power Mac G3 Desktop Features:

• ATAPI or SCSI Zip drive

• Ultra Wide SCSI PCI card

• 4 GB or 9 GB Ultra Wide 3.5” SCSI hard drive(s) (replaces 4 GB or 6 GB ATA hard drive(s))

• DVD-ROM Drive (in place of CD-ROM drive)

• 10/100 BaseT ethernet card

• FireWire DVC card

Basics Data Buses - 5

Data Buses

The data buses on the Power Macintosh G3 Desktop include:

• Narrow SCSI-1: The SCSI-1 chain transfers data at up to 5 MB per second. The narrow SCSI-1 chain supports up to seven internal and external SCSI devices. The Narrow SCSI-1 bus is used to connect the ZIP drive (if present) and any SCSI-1 hard drives.

• Ultra Wide SCSI-3 (provided on Ultra Wide SCSI card, which is optional): The Ultra Wide SCSI-3 chain can transfer data at up to 40 MB per second and supports up to three internal devices. This bus is used to connect any Ultra Wide SCSI devices.

• EIDE (Extended Integrated Drive Electronics): There are two EIDE connectors on the logic board (the ATAPI CDROM drive or DVD-ROM drive uses one of these connectors, and if an ATA hard drive is installed, it uses the second connector).

Basics Data Buses - 6

Note:

Some Power Mac G3 system use a Master/Slave interface. See “Support for Master and Slave” later in this section for more information.

The following table gives more information about the data buses in the Power Macintosh G3 Desktop computer.

Basics Data Buses - 7

Table 1: Internal Buses on G3 Desktop

Interface

SCSI-3 (Ultra Wide)

Connector

Type

68-Pin

Requires Ultra Wide SCSI PCI card.

Notes

EIDE 40-Pin There are two EIDE connectors on

the logic board.

SCSI-2

50-Pin Requires Ultra Wide SCSI PCI card.

(Fast) SCSI-1

(Narrow)

50-Pin Standard connector on logic board.

Used to connect internal devices to Narrow SCSI-1 bus (e.g. ZIP drive).

Max # of

Drives

Max Data

Transfer

Rate

40 MB per second

—

10 MB per second

5 MB per second

Basics Data Buses - 8

Notes for Table 1:

The Ultra Wide SCSI PCI card is optional on the G3 Desktop unit. The Apple Ultra Wide

SCSI card and cable allow you to connect a maximum of 2 devices to this bus.

Physical space inside the computer limits this number to 2.

The ATAPI CD-ROM drive, ATAPI DVD-ROM drive, and ATA hard drive (if present) use

this bus.

Ultra Wide SCSI PCI card is optional on the G3 Desktop unit. It’s best not to use this bus because it will cause any Ultra Wide SCSI-3 devices to transfer data at the slower SCSI-2 rate. No cable is provided for the SCSI-2 bus.

The G3 Desktop unit may come with a Zip drive attached to this bus. You can add additional SCSI-1 devices as long as the combined number of internal and external devices is no more than seven.

Basics Data Buses - 9

Narrow SCSI-1 Bus

All internal and external devices on the SCSI-1 chain must have unique ID numbers. SCSI ID numbers 0 through 6 are available. Always terminate the last internal and the last external SCSI-1 device.

Ultra Wide SCSI-3 Bus

Ultra Wide SCSI support is offered on the Power Macintosh G3 Desktop as an optional feature via an Ultra Wide SCSI PCI card (p/n 661-2011). If present, this card is installed in the first PCI slot on the logic board. You can connect a total of two internal devices to the Ultra Wide SCSI-3 bus.

Important

Wide SCSI-3 bus, refer to the information on cable length limits and termination later in this section.

: Before you connect an internal device to the Ultra

Basics Data Buses - 10

Important

Ultra Wide SCSI cable can be found in the Take-Apart chapter in the Hard Drive topic.

All devices on the same SCSI bus must have unique ID numbers, but devices on different SCSI buses may use the same SCSI ID number. (For example, you could have a removable media drive with ID number 3 connected to the Narrow SCSI-1 bus and a hard drive with ID number 3 connected to the Ultra Wide SCSI-3 bus.)

Some of the drives that were installed at the factory, as well as the SCSI card itself, have already reserved certain SCSI ID numbers on the Ultra Wide SCSI-3 bus. Other ID numbers are available for assignment to SCSI devices that are added later.

The following table provides more information on assigning SCSI ID numbers to Ultra Wide devices.

: Detailed information on how to route and tape the

Basics Data Buses - 11

Table 2: Assigning Ultra Wide SCSI ID Numbers

Ultra Wide

SCSI ID #

0 1

2 — 6

8 —15

Important

are both terminated. Other SCSI devices you install and connect to the internal Ultra Wide SCSI-3 bus must not be terminated, or the computer will malfunction.

Factory-installed hard drive (terminated)

Factory-installed hard drive (optional)

Available (but not recommended)

SCSI PCI card (terminated)

Available

: The factory-installed internal hard drive and the SCSI card

Device

Basics Data Buses - 12

EIDE Bus

The internal EIDE bus supports the internal CD-ROM or DVD-ROM drive. You can connect another EIDE device, such as an EIDE hard drive, to the second channel of the EIDE bus. (Note that in the standard G3 Desktop configuration, there is already an ATA hard drive attached to the second EIDE channel. Some build-to-order G3 Desktops, however, come with the optional Ultra Wide SCSI card and Ultra Wide SCSI hard drive, in which case the second EIDE channel is available.) You can install an EIDE device in one of the available expansion bays.

Connecting EIDE Devices to the Logic Board

There are two EIDE connectors on the G3 Desktop logic board, which are marked J9 and J10. Use the internal ribbon cable with the 40-pin connector to connect EIDE

Basics Data Buses - 13

devices to the EIDE bus.

If you are connecting a single device to the EIDE bus, you should use the J9 connector (the one closer to the rear panel). If you plug a single device into the J10 EIDE connector and leave J9 empty, the device may not boot.

If the Power Macintosh G3 Desktop ships with two EIDE devices (a CD-ROM or DVD-ROM drive and an ATA hard drive), both EIDE connectors (J9 and J10) will be automatically used. Service Providers should keep the J9 vs. J10 issue in mind, however, when testing G3 Desktop units.

Support for Master and Slave

Basics Data Buses - 14

hard drives or removal media devices to their system.

The Power Macintosh G3 Desktop units that support this feature can only be identified by looking at the logic board itself and verifying the revision of the built-in video ASIC made by ATI Technologies. If you are looking at the logic board with the rear connector towards you, the video ASIC is located approximately 1” from the built-in video connector on the logic board.

If the ASIC reads: “ATI 3D Rage II+DVD,” the logic board does not support the master and slave configuration; If the controller reads: “ATI 3D Rage Pro PCI,” the logic board does support the master and slave configuration.

Note:

Although the ATI chip is an ideal way to identify the version of the logic board, it does not control the EIDE interface.

Basics Data Buses - 15

Conﬁguring or Connecting Master/Slave Devices

Each IDE channel can support either one or two devices. All Power Macintosh G3's have two ATA/IDe channels. ATA/IDE devices each contain their own integrated controllers, and so in order to maintain order on the channel, it is necessary to have some way of differentiating between the two devices. This is done by giving each device a designation as either master or slave, and then having the controller address commands and data to either one or the other. The drive that is the target of the command responds to it, and the other one remains silent.

Note:

Despite the hierarchical-sounding names of "master" and "slave", the master drive does not have any special status compared to the slave one; they are really equals in most respects. The slave drive doesn't rely on the master drive or anything like that, despite the names.

Basics Data Buses - 16

Devices are designated as master or slave using jumpers, small connectors that fit over pairs of pins to program the drive through hardware. Each hard drive manufacturer uses a different combination of jumpers (usually named differently) for specifying whether its drive is master or slave on the channel. Some disks put this information right on the top label of the drive itself, while many do not; it sometimes takes some hunting around to find where the jumper pins are on the drive even once you know how the jumpers are supposed to go.

ATAPI drives, or ATA/IDE devices that support removable media like CD-ROM's are jumpered in exactly the same way, and they have the advantage of having their jumpers much more universally labeled than their hard disk counterparts.

If you are using two drives on a channel, it is important to ensure that they are jumpered correctly. Making both

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