Macintosh Quadra 800 General Maintenance

Macintosh Quadra 800

Maintenance guidance for the Macintosh Quadra 800 and the Workgroup Server 80, which Apple services in one manual.

Opening the case

Unplug the mains lead. Loosen the four captive cover screws, slide the cover forward about 1/2 inch and lift it off.

The floppy drive, hard drive, CD-ROM drive and tape drive each slide out once their retaining clip is pressed and their cables are disconnected. The power supply comes out after the chassis support brace and the logic board power cable: press the latch, slide the supply forward and pull it out.

To remove the logic board, take off the reset/interrupt actuator and the board's screw, slide the board forward until the slot lines up with the tab, lift the latch at the rear and pivot the front of the board out, then disconnect the power, speaker, LED, SCSI, floppy and CD-ROM audio cables. Apple warns that the LED cable must be reconnected on reassembly for the system to work, and the symptom charts include a "This startup disk will not work on this Macintosh model" message whose cures start with attaching the LED cable.

Expansion cards come out after pinching the two handles of the NuBus card retainer; grasp each end of the card, holding the left side by its metal bracket, and pull it straight out evenly so the connector pins do not bend.

Regular cleaning

• Blow dust out of the power supply vents, the fan and the logic board with compressed air.
• Keep the vents clear. Apple's first cure for intermittent shutdowns is to clear them: the thermal protection circuit can shut the machine down, and it should work again after 30 to 40 minutes.
• Clean the mouse. Apple's chart for a cursor that does not move includes inspecting the inside of the mouse for dirt and cleaning it.
• For yellowed plastics see Retrobrite.

The floppy drive is the 1.4 MB SuperDrive. Apple recommends dust shields on SuperDrives in this machine, and replacement drives ship with them fitted. For cleaning and lubrication see Macintosh Floppy Drive Maintenance.

PRAM battery

The PRAM and clock run from a lithium cell in a latched holder on the logic board. Apple's check needs the cover and the logic board removed:

1. Set the voltmeter to the 10 V DC scale.
2. Hold the positive probe to the positive end of the cell (marked "+" on the logic board) and the negative probe to the negative end.
3. If the cell reads below 3.2 V, replace it.

To replace it, prise open the latch at the end of the holder with a small flat-blade screwdriver, lift off the cover and lift the cell out. Apple's charts also list a battery check for intermittent shutdowns.

If the cell has leaked, remove it and clean the board before powering it again. See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.

Connectors and sockets

Clean with a contact cleaner such as DeoxIT D5 and let it dry before powering on:

• the four 72-pin DRAM SIMM sockets (60 ns SIMMs; these are not the 30-pin SIMMs of older Macintosh models or the 64-pin SIMMs of the Macintosh IIfx);
• the two VRAM SIMM slots, which form one bank (80 ns or faster VRAM SIMMs);
• the three NuBus slots and the processor-direct slot;
• the SCSI data cable at both ends, and the internal drive power cables.

Expansion slots

The three NuBus slots occupy slot addresses $C, $D and $E. The processor-direct slot is in line with slot $E, so a PDS card leaves two NuBus slots. The NuBus includes NuBus '90 features, among them a 20 MHz clock; double-rate block transfers work between cards but not to or from the logic board. Each slot is allowed 15 W.

SCSI

The bus takes up to eight devices including the computer, which is always ID 7. One 53C96 controller drives both the internal and external bus:

• Only the device at the end of the internal SCSI cable may carry terminators. Apple warns that with none the computer will malfunction, and with more than one it will malfunction and the logic board may be damaged. With no internal devices, disconnect the internal cable.
• Do not fit a terminator to an empty external port. When no external device is connected, circuitry on the logic board terminates the bus near the connector; it detects an external terminator at reset and switches itself out.
• An internal CD-300 is jumpered to ID 3. Check that no other device uses 3 before fitting one.

Power supply

Apple's specification is 100-240 V AC, 50-60 Hz single phase, 200 W continuous. After the logic board and expansion cards, the supply has 16.0 A at +5 V and 4.3 A at +12 V left for internal devices. The Service Source has no rail tolerance table and no voltage adjustment; check the rails at a drive power connector against nominal, and watch for a rail that sags when a drive spins up.

The keyboard's power key starts the machine. The mechanical switch on the back can be locked on so the machine restarts after a power failure.

For the power supply's capacitors see Macintosh Quadra 800 Capacitor Replacement Guide.

Specifications for reference

Item	Apple's figure
Size	14.25 × 7.75 × 16 in (360 × 196 × 396 mm)
Weight	24 lb (Apple prints 11.3 kg; 24 lb is 10.9 kg)
Operating temperature	10-40 °C (50-104 °F)
Storage temperature	−40 to 47 °C
Relative humidity	5-90 %, non-condensing

Related pages

• Macintosh Quadra 800
• Macintosh Quadra 800 Troubleshooting
• Macintosh Quadra 800 Capacitor Replacement Guide
• Recommended Tools