Macintosh Quadra 800 Troubleshooting

Macintosh Quadra 800

Fault diagnosis for the Macintosh Quadra 800 and Workgroup Server 80, built on the symptom charts in Apple's Service Source. Apple lists cures in order of likelihood: try the first, check whether the symptom persists, and refit the original part before moving to the next cure. Where Apple says "replace logic board", it also says to keep the customer's SIMMs.

Error chords

Error chords (Apple's cures, in order)

Symptom	Cures
One-part error chord during start-up	Disconnect the SCSI data cable from the hard drive and restart; if start-up is then normal, initialise the hard drive, and if the chord still sounds, replace it. Disconnect the floppy drive cable and restart; if start-up is then normal, replace the floppy drive. Replace the logic board.
Two-part error chord during start-up	Check the SIMMs.

For Sad Mac codes see Sad Mac Error Codes.

System and power

System symptoms (Apple's cures, in order)

Symptom	Cures
Does not power on: screen black, fan not running, LED not lit	Check the power cables; plug the monitor directly into the wall and confirm it has power; replace the power cord; replace the power supply; replace the logic board.
Clicking, chirping or thumping	Replace the power supply; replace the logic board; replace the floppy drive cable; replace the floppy drive.
System shuts down intermittently	Make sure the vents are clear (the thermal protection circuit can shut the system down; it should recover after 30-40 minutes); replace the power cord; check the battery; replace the power supply; replace the logic board.
System crashes or hangs intermittently	Check the system software is 7.1 or later, known-good and System 7 compatible; clear PRAM (hold Command-Option-P-R at start-up); replace the SIMMs; replace the logic board; replace the power supply.
"This startup disk will not work on this Macintosh model" at start-up	Check the start-up disk; attach the LED cable to the logic board; replace the LED cable; replace the logic board.

Apple's take-apart procedure warns that the LED cable must be reconnected after the logic board has been out, or the system will not work.

Apple's electrical specification is 100-240 V AC, 50-60 Hz single phase, 200 W continuous, with no rail tolerance table and no voltage adjustment. The power supply is Apple part 661-1687; its capacitors are covered on the Macintosh Quadra 800 Capacitor Replacement Guide.

The PRAM battery is a lithium cell. Apple's check is made with the logic board out: replace the cell below 3.2 V.

Video

Video symptoms (Apple's cures, in order)

Symptom	Cures
Screen black; audio and drive work, fan running, LED lit	Adjust monitor brightness; replace the monitor; replace the video cable; move any video card to a different slot; replace the video card; clear PRAM; replace the SIMMs; replace the logic board; replace the power supply.
Screen black; audio and drive do not work, fan running, LED lit	Replace the video cable; move any video card to a different slot; replace the video card; replace the SIMMs; replace the logic board; replace the power supply.
Partial or whole screen bright, audio present, no video information	Replace the monitor; replace the video cable; move any video card to a different slot; replace the video card; clear PRAM; replace the logic board.

The built-in video uses one DB-15 port and two VRAM SIMM slots forming one bank; it supports Apple monitors up to 16 bits per pixel as well as VGA and SVGA. Pixel depth depends on the VRAM fitted; see the table on Macintosh Quadra 800.

Floppy drive

Floppy drive symptoms (Apple's cures, in order)

Symptom	Cures
Internal floppy drive does not operate	Try a known-good disk; replace the floppy drive cable; replace the floppy drive; replace the logic board; replace the power supply.
Disk ejects at start-up; icon with blinking "X"	Try a known-good system disk; clear PRAM; replace the floppy drive cable; replace the floppy drive; replace the logic board.
Does not eject disk	Switch off, then hold the mouse button down while switching on; replace the floppy drive cable; replace the floppy drive; replace the logic board.
Tries to eject but the disk does not come out	Push the disk fully in; reseat the floppy bezel and drive so the bezel slot lines up with the drive; eject the disk manually; replace the floppy drive.
Internal floppy drive runs continuously	Try a known-good disk; replace the floppy drive cable; replace the floppy drive; replace the logic board.
An MS-DOS drive does not recognise a disk formatted on the 1.4 MB drive	Format disks in the MS-DOS drive first if they are to be used in both.

For cleaning and lubrication of the SuperDrive see Macintosh Floppy Drive Maintenance.

Hard drive and SCSI

Hard drive symptoms (Apple's cures, in order)

Symptom	Cures
Single internal drive does not operate; drive does not spin	Replace the drive power cable; replace the drive; replace the power supply.
No internal SCSI drives operate	Check for duplicate SCSI IDs; replace the SCSI data cable; replace the power supply; replace the logic board.
Works with internal or external SCSI devices but not both	Check for duplicate SCSI IDs; replace the terminator on the external device; make sure the device at the end of the internal cable is the only terminated internal device; troubleshoot the external device.
Drive does not appear on the desktop	Check for duplicate SCSI IDs; update the driver with Apple HD SC Setup and run Disk First Aid; replace the SCSI cable; initialise the drive with HD SC Setup if it is not initialised; try a known-good drive, and if that does not work either, refit the original and replace the logic board.

The internal and external bus are driven by one 53C96 controller. Only the device at the end of the internal cable may be terminated; Apple warns that terminators in more than one internal device can damage the logic board. With nothing plugged into the external port, the logic board terminates the bus itself, so do not fit a terminator to an empty port. An internal CD-300 is jumpered to ID 3.

CD-ROM drive

CD-ROM symptoms (Apple's cures, in order)

Symptom	Cures
Drive does not accept a disc	Try another disc; replace the CD-ROM mechanism.
No CD-ROM icon on the desktop	Check the CD-ROM software is installed; replace the CD-ROM mechanism; replace the SCSI data cable; replace the power supply.

Keyboard, mouse and printing

Peripheral symptoms (Apple's cures, in order)

Symptom	Cures
Cursor does not move	Check the mouse connection; clean the inside of the mouse; if the mouse was on the keyboard, plug it into a computer ADB port (if it now works, replace the keyboard); if it fails on every port, replace the mouse; replace the logic board.
Cursor moves, but clicking has no effect	Replace the mouse; replace the logic board.
Double-click does not open an application, disk or server	Remove duplicate System folders; clear PRAM; try the mouse on a computer ADB port; replace the mouse; replace the logic board.
No response to any key	Check the keyboard connection; replace the keyboard cable; replace the keyboard; replace the logic board.
Known-good serial printer does not print	Check the system software is 7.1 or later; check the Chooser; replace the printer cable; replace the logic board.
Known-good network printer does not print	Check the system software is 7.1 or later; check the Chooser; replace the logic board.

Sound

No sound from the speaker: check that the Control Panel volume is 1 or above, then replace the speaker, then the logic board.

Related pages

• Macintosh Quadra 800
• Macintosh Quadra 800 General Maintenance
• Macintosh Quadra 800 Capacitor Replacement Guide
• Sad Mac Error Codes
• Macintosh Floppy Drive Maintenance