Macintosh Quadra 700 Troubleshooting

Macintosh Quadra 700

Fault diagnosis for the Macintosh Quadra 700, built on the symptom charts in Apple's Macintosh IIcx/IIci/Quadra 700 Service Source. Apple lists the cures for each symptom in order of likelihood: try the first, check whether the symptom persists, and if it does, 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.

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 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.
System shuts down intermittently	Make sure the vents on the sides and top of the case 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 locks up intermittently	Check the system software version; check the application with known-good software; replace the SIMMs; replace the logic board; replace the power supply.

The Quadra 700 starts from the power key on the ADB keyboard. The logic board's soft-power circuit runs from a +5 V trickle supply that is present whenever the machine is plugged in, and the +5 V feed to the ADB ports passes through a 1.5 A fuse, F3. If neither the power key nor any ADB device works, check F3 as well as the keyboard and its cable.

Apple's electrical specification is 100-240 V AC, automatically configured, 50-60 Hz, 130 W maximum and 90 W continuous, not including the monitor. The Service Source gives no rail tolerance table and no voltage adjustment. Console5 lists the supply as the Astec AA15831, shared with the Macintosh IIci; its capacitor list is on the Macintosh Quadra 700 Capacitor Replacement Guide.

Video

Video symptoms (Apple's cures, in order)

Symptom	Cures
Screen dark; audio and drive work, fan running, LED lit	Adjust monitor brightness; replace the monitor; replace the video cable; move the video card to a different slot; replace the video card; replace the VRAM SIMMs; replace the SIMMs; replace the logic board; replace the power supply.
Screen dark; audio and drive do not work, fan running, LED lit	Replace the video cable; replace the monitor; replace the VRAM SIMMs; remove NuBus cards; remove peripherals; 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 the video card to a different slot; replace the video card; replace the logic board.
Screen completely dark, fan not running, LED not lit	Plug the monitor directly into a wall socket and confirm it has power; check the battery; replace the power supply; replace the logic board.

Built-in video uses one DB-15 port and supports 640 × 480 at up to 8 bits per pixel and 640 × 870 at up to 16 shades of grey. The VRAM SIMMs appear early in both dark-screen charts, so reseat and swap them before condemning the logic board.

Floppy drive

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

Symptom	Cures
Audio and video present, internal drive does not operate	Try a known-good system disk; disconnect all external SCSI devices; replace the floppy drive cable; replace the floppy drive; replace the logic board; replace the power supply.
Disk ejects; display shows an icon with a blinking "X"	Try a known-good system disk; replace the floppy drive cable; replace the floppy drive; replace the logic board.
Will not eject disk	Switch off, then hold the mouse button down while switching on; eject the disk manually; replace the floppy drive.
Attempts to eject but the disk does not come out	Push the disk fully in; eject it manually; replace the floppy drive.

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
Internal hard drive runs continuously	Replace the drive data cable; replace the drive; replace the logic board.
Internal hard drive does not operate	Replace the drive data cable; replace the drive power cable; replace the drive; replace the logic board.
Works with the internal drive or an external SCSI device, but not both	Check that the external device's SCSI ID is not 7 and not the same as the internal drive's; replace the terminator on the external device; check that the internal drive has a terminator.

Every Quadra 700 that shipped without an internal hard drive has a SCSI termination block fitted to the logic board's SCSI connector, and Apple's instruction is to remove it after fitting an internal drive. On a machine that has had a drive added, check for this block first.

The SCSI controller is an NCR 53C96 (U20). Termination power to the external DB-25 and internal 50-pin connectors passes through a 1.5 A fuse, F2.

Keyboard, mouse and printing

Peripheral symptoms (Apple's cures, in order)

Symptom	Cures
Cursor does not move	Restart; check the mouse connection; if the mouse was plugged into the keyboard, plug it into a computer ADB port and disconnect the keyboard (if it now works, replace the keyboard); if it fails on every ADB 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 files; clear parameter RAM (System 7: hold Command-Option-P-R during start-up); 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 ImageWriter or LaserWriter does not print	Make sure the system is 6.0.4 with Finder 6.1 or later; check the Chooser and Control Panel settings; (ImageWriter) replace the printer cable, then the logic board.

Sound and clock

Miscellaneous symptoms (Apple's cures, in order)

Symptom	Cures
No sound from the speaker	Check that the Control Panel volume is 1 or above; replace the speaker; replace the logic board.
Clock not running	Replace the battery; replace the logic board.

The battery is a 3.6 V lithium cell (BT1). Apple's test is to measure it on the 10 V DC range and replace it below 2.8 V. If it has leaked, clean the board before further diagnosis; see Battery Explosion, Capacitor or Corrosion Damage.

Ethernet

Apple's Service Source describes the built-in Ethernet port as an "AUI-15 connector". The schematic shows a 14-pin connector (J7) whose supply to the external transceiver passes through a 1.5 A fuse, F1. Low End Mac identifies it as Apple's AAUI connector; the Quadra 700 and 900 were the first Macintosh models with built-in Ethernet. The port needs an AAUI transceiver; if a known-good transceiver gets no power, check F1.

Start-up tones and Sad Mac codes

The Service Source for this machine has no start-up tone or Sad Mac table. For decoding a Sad Mac code see Sad Mac Error Codes.

Logic board capacitors

The Quadra 700 logic board is built with tantalum capacitors, not the aluminium electrolytics that leak on most Macintosh boards of the period, so leaked capacitor electrolyte is not a usual cause of faults on this machine. The power supply does contain electrolytics; see Macintosh Quadra 700 Capacitor Replacement Guide.

Related pages

• Macintosh Quadra 700
• Macintosh Quadra 700 General Maintenance
• Macintosh Quadra 700 Capacitor Replacement Guide
• Sad Mac Error Codes
• Macintosh Floppy Drive Maintenance