Macintosh Quadra 700 General Maintenance

Maintenance guidance for the Macintosh Quadra 700. Apple services the Quadra 700 in the same manual as the Macintosh IIcx and Macintosh IIci, and much of the service data below is shared with those models.

The Quadra 700 (left) beside a Quadra 900

Opening the machine

Remove the Phillips screw at the rear, pull up on the tabs and lift the cover until it comes free at the front. The power supply is held by a latch and lifts straight out. The drive mount is held by one screw and a latch, and the floppy and hard disk cables come off the logic board before it lifts out. The logic board slides towards the front of the case and lifts out once the expansion cards, power supply, drive mount, reset/interrupt switch and speaker bracket are removed. Before refitting it, check that the metal grounding tabs around the rear port holes are not folded across the holes.

Unplug the mains lead before opening the case. The power supply's primary side is at mains potential and its reservoir capacitors hold a charge after the machine is switched off.

Regular cleaning

• Power off and disconnect everything before opening the case.
• Blow dust off the logic board, power supply and fan with compressed air.
• Keep the vents on the sides and top of the case clear. Apple's symptom chart for intermittent shutdowns starts with them: the thermal protection circuit can shut the system down, and it should be usable again after 30 to 40 minutes.
• For yellowed plastics see Retrobrite.

The floppy drive is the 1.4 MB SuperDrive. Apple ships replacement drives with a dust shield fitted and says a drive must be cleaned before a shield is added to it. For cleaning and lubrication see Macintosh Floppy Drive Maintenance.

PRAM battery

The Quadra 700 uses a 3.6 V lithium cell (BT1 on Apple's schematic). To reach it, remove the cover, the power supply and the drive mount. Apple's check is to set the voltmeter to the 10 V DC range, hold the positive probe to the positive end of the cell (marked "+" on the logic board) and the negative probe to the other end, and replace the cell if it reads below 2.8 V.

The cell sits in a holder with a latched cover. Prise the latch at the end of the holder open with a small flat-blade screwdriver, lift off the cover and lift the cell out.

Apple's symptom charts include a battery check for a machine whose screen is dark with the fan and LED off, for intermittent shutdowns, and for a clock that does not keep time.

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

Capacitors

The Quadra 700 logic board is built with tantalum capacitors, not the surface-mount aluminium electrolytics that leak on most Macintosh boards of the period, and a logic board recap is not part of routine service. A rail shorted to ground can still be a failed tantalum; see Capacitor Failure Symptoms.

The power supply contains aluminium electrolytics and is the part that needs recapping. See Macintosh Quadra 700 Capacitor Replacement Guide.

Connectors and sockets

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

• the DRAM SIMM sockets (Apple fits 80 ns SIMMs; 120 ns SIMMs from a IIcx will not work in a Quadra 700 board);
• the VRAM SIMM sockets. Apple's dark-screen charts list "Quadra 700: Replace VRAM SIMMs" among the early steps;
• the ROM SIMM socket (1 MB of ROM is soldered to the board, with a ROM SIMM socket available);
• the two NuBus slots and the processor-direct slot;
• the power supply connector on the logic board.

Logic board fuses

Apple's schematic shows three 1.5 A fuses on the logic board: F1 on the supply to the Ethernet connector J7, F2 on SCSI termination power, and F3 on the +5 V feed to the ADB ports. If the ADB devices, an Ethernet transceiver or an external terminator get no power, check the matching fuse.

SCSI termination block

Every Quadra 700 that shipped without an internal hard drive has a SCSI termination block fitted to the logic board's SCSI connector. Apple's instruction is to remove the block after installing an internal hard drive. Check for it first on any Quadra 700 that has had a drive retrofitted and has SCSI problems.

Power supply

Apple's electrical specification is 100-240 V AC, automatically configured, 50-60 Hz single phase; 130 W maximum and 90 W continuous, not including monitor power. There is no voltage selector.

Console5 lists the Astec AA15831 as the supply in the Quadra 700 and the IIci, and advises identifying the supply by the maker's label, not by Apple's part number. The Service Source has no voltage-adjustment procedure and no rail tolerance table.

A +5 V trickle supply is present whenever the machine is plugged in and feeds the soft-power control circuit on the logic board, which is how the keyboard's power key starts the machine.

Apple's symptom charts send these to the power supply:

• a machine that does not power on (black screen, fan not running, LED not lit), after checking the cables, the monitor's own power and the mains lead;
• clicking, chirping or thumping noises;
• intermittent shutdowns not explained by blocked vents, the mains lead or the battery.

Fan

To replace the fan, remove the cover and the power supply. Squeeze the two bracket latches to release them from the metal tabs, push them up until the fan cable connector can be reached, disconnect the cable from the power supply and pull the bracket out of the case. Then release the two latches that hold the fan in the bracket. When refitting, push the fan wire far enough into the power supply case that the blades cannot strike it.

Related pages

• Macintosh Quadra 700
• Macintosh Quadra 700 Troubleshooting
• Macintosh Quadra 700 Capacitor Replacement Guide
• Battery Explosion, Capacitor or Corrosion Damage
• Recommended Tools