Editing Macintosh Quadra 700 Troubleshooting

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[[File:Macintosh Quadra 700 (photo).jpg|thumb|right|300px|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.<ref name="ss700">Apple Computer, ''Macintosh IIcx/IIci/Quadra 700'' Service Source. Hosted here as [[Macintosh IIcx/IIci/ Quadra 700 Service Source]] ([[:File:Quadra_700.mac_iicx.iici.pdf]]). Troubleshooting: General (PDF p. 17) and Symptom Charts (PDF pp. 18-29); Specifications (pp. 5-15); Additional Procedures: Battery Verification (pp. 70-71) and SCSI Termination (p. 77).</ref> Where Apple says "replace logic board", it also says to keep the customer's SIMMs.

== System and power ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

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.<ref name="sch700">Apple Computer, ''Macintosh Quadra 700'' logic board schematic, drawing 050-8020 rev. C, sheets 2-31 of 34. Hosted here as [[:File:Macintosh Quadra 700 Schematic.pdf]]. Sheet 19 (53C96 SCSI controller U20, fuse F2 on termination power), sheet 26 (ADB connectors and power control, fuse F3, trickle +5 V), sheet 27 (real-time clock, battery BT1 3.6 V), sheet 31 (SONIC Ethernet, 14-pin connector J7, fuse F1).</ref> 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.<ref name="ss700" /> 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]].<ref name="c5kit">Console5, [https://console5.com/store/macintosh-astec-aa15831-power-supply-cap-kit-mac-iici.html "Macintosh ASTEC AA15831 Power Supply Cap Kit - Mac IIci / Quadra 700"] (retrieved 2026-09-30).</ref>

== Video ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

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.<ref name="ss700" /> The VRAM SIMMs appear early in both dark-screen charts, so reseat and swap them before condemning the logic board.

== Floppy drive ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

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

== Hard drive and SCSI ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

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.<ref name="ss700" /> 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.<ref name="sch700" />

== Keyboard, mouse and printing ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

== Sound and clock ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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.
|}
<ref name="ss700" />

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.<ref name="sch700" /><ref name="ss700" /> 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.<ref name="ss700" /><ref name="sch700" /> Low End Mac identifies it as Apple's AAUI connector; the Quadra 700 and 900 were the first Macintosh models with built-in Ethernet.<ref name="lem900">Adam Geller, [https://lowendmac.com/1991/quadra-900/ "Quadra 900"], Low End Mac (retrieved 2026-09-30): "The Quadra 700 and 900 were the first Macs with built-in ethernet, using Apple's AAUI connector."</ref> 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.<ref name="ramfaq">Recap-a-Mac, [https://recapamac.com.au/recapping-service/ "Recapping Service"], FAQ "Why do you use tantalum capacitors as replacements?" (retrieved 2026-09-30): "Apple actually used tantalum capacitors instead of surface mount electrolytics for some of their vintage Macs (such as the Quadra 700 and Quadra 900)".</ref><ref name="ars700">Chris Wilkinson, [https://arstechnica.com/information-technology/2020/12/it-still-runs-on-your-imagination-passing-2020-time-with-a-macintosh-quadra-700/ "Working from home at 25MHz: You could do worse than a Quadra 700 (even in 2020)"], ''Ars Technica'', 11 December 2020.</ref> 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]]

== References ==

<references />

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[[Category:Apple Vintage Computers]]
[[Category:Apple Troubleshooting Guides]]