Macintosh IIvx Troubleshooting
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Fault-finding for the Macintosh IIvx. The tables are Apple's symptom charts from the Service Source it shares with the Macintosh IIvi and Performa 600, with the cures in Apple's order: try the first, check whether the symptom persists, and if a module swap does not cure it, refit the original before moving on.[1] Apple's cures stop at module level; the known faults follow the charts.
Power and start-up
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Screen completely dark, fan off, LED off | Check the external power cables; remove peripherals; remove the NuBus cards and switch on again (combined cards should not draw more than 45 W); remove the accelerator card; power supply; logic board |
| Screen dark, no audio or drive activity, fan and LED on | Remove peripherals; remove NuBus cards; DRAM SIMMs; VRAM SIMMs; power supply; logic board |
The machine is switched on from the keyboard's power key, which the 68HC05 microcontroller watches using the power supply's +5 V trickle output; that output is live whenever the machine is plugged in. Shut Down turns the supply off through the same controller.[2] A blank screen for some seconds after switching on is normal: RAM is tested and sized before video starts, longer with more RAM fitted.[2]
For the Sad Mac codes of the Macintosh II family, see Sad Mac Error Codes. Apple's charts for this machine do not list them.
Video
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Dark screen; audio and a drive working, fan and LED on | Monitor brightness; monitor; video cable; VRAM SIMMs; logic board |
| Screen bright, audio present, no picture | Monitor; video cable; VRAM SIMMs; logic board |
VRAM SIMMs go in identical pairs, 100 ns or faster. Apple warns that VRAM which does not meet its read-transfer timing can leave visible artefacts on the screen. There is no 1-bit mode on Apple's 12-inch RGB monitor.[2]
Floppy, hard and CD-ROM drives
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Floppy drive does not work | Floppy cable; floppy drive; logic board |
| Disk ejects and a Mac icon with a blinking X appears | Another disk; floppy cable; floppy drive; logic board |
| Disk will not eject | Switch off and hold the mouse button down while switching on; eject manually; floppy cable; floppy drive |
| Drive tries to eject but fails | Push the disk fully in; push a straightened paper clip into the hole beside the slot; floppy drive |
| Hard drive runs continuously | Turn off virtual memory and see whether it stops; SCSI data cable; hard drive; logic board |
| Hard drive does not work | SCSI data cable; SCSI power cable; hard drive; logic board |
| CD-ROM drive will not accept a disc | Try another disc; CD-ROM mechanism |
| No CD-ROM icon on the desktop | Reinstall the CD software and check the CD-ROM extensions are in the System Folder; reinstall system software; CD-ROM mechanism; power supply; SCSI data cable |
| Works with the internal or an external SCSI device, not both | External devices must use different SCSI IDs from internal ones; the hard drive must be terminated and the CD-ROM must not be; external terminator; the external device's SCSI select cable |
The logic board's active terminator ends the internal bus when nothing is plugged into the external port. Apple's internal CD-ROM is SCSI ID 3.[2] See Macintosh HDD Maintenance and Macintosh Floppy Drive Maintenance.
Keyboard and mouse
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Cursor does not move | Restart; mouse connection; connect the mouse to the computer's ADB port, and replace the keyboard if it then works; mouse; logic board |
| Cursor moves, clicking does nothing | Mouse; logic board |
| Double-click does not open anything | Remove duplicate System files; clear PRAM (Command-Option-P-R at start-up, before "Welcome to Macintosh"); check keyboard and mouse as above; logic board |
| No response from the keyboard | Keyboard connection; keyboard cable; keyboard; logic board |
| Beep whenever a key is pressed | Turn off Slow Keys in the Easy Access control panel |
The ADB port supplies +5 V on pin 3 through a 1 A fuse.[2]
Known faults
[edit | edit source]Battery
[edit | edit source]Apple's test is on the 10 V DC range; replace the battery below 2.8 V.[1] Recap-a-Mac's photograph of a IIvi logic board shows the battery holder, BT1, and the area around it destroyed by a leaking cell.[3] Remove the battery from a stored machine, and neutralise lithium residue with bicarbonate of soda. See Battery Explosion, Capacitor or Corrosion Damage.
Capacitors
[edit | edit source]The logic board has six 47 µF surface-mount electrolytics and two 220 µF axials, which leak with age.[3] See Macintosh IIvx Capacitor Replacement Guide and Capacitor Failure Symptoms.
Related pages
[edit | edit source]- Macintosh IIvx
- Macintosh IIvx General Maintenance
- Macintosh IIvx Capacitor Replacement Guide
- Macintosh IIvi Troubleshooting
- Sad Mac Error Codes
References
[edit | edit source]- ↑ 1.0 1.1 Apple Computer, Macintosh IIvx, Macintosh IIvi, Performa 600 Service Source, File:Macintosh iivx.vi.perf 600.pdf; see Macintosh IIvx/IIvi/Performa 600 Service Source. Troubleshooting, PDF pp. 15-24: General p. 15; Video pp. 16-17; Floppy Drive pp. 18-19; Hard Drive p. 20; CD-ROM Drive p. 21; Peripherals pp. 22-24. Battery Verification pp. 68-69.
- ↑ 2.0 2.1 2.2 2.3 2.4 Apple Computer, Macintosh IIvx Developer Note (1992), also covering the IIvi and Performa 600, File:Macintosh IIvx IIvi and Performa 600 Developer Note.pdf; see Macintosh IIvx IIvi and Performa 600 Developer Note. Printed page numbers: video modes and FPU pp. 4-5; RAM p. 9; VRAM p. 10; ADB, clock and PRAM p. 19; soft power p. 20; power supply p. 28; internal SCSI devices and CD-ROM ID pp. 31-32.
- ↑ 3.0 3.1 Macintosh IIvi, Recap-a-Mac—link(accessed 2026-09-30) Annotated photograph of logic board 820-0373-A, hosted here as File:Mac IIvi Recap Guide.jpg; the IIvi is not "immune from leaky capacitors and exploding batteries".
