Macintosh IIvx Troubleshooting

This guide covers common faults with the Macintosh IIvx, including startup failures, video problems, CD-ROM issues, and storage errors.

Preliminary Checks

Before detailed troubleshooting:

**Power Issues**
Symptom	Possible Cause	Action
Completely dead	Blown fuse, failed PSU, bad cord	Check outlet; test power cord; check PSU fuse
Clicking or ticking	Failed PSU capacitors	Recap power supply
Powers on briefly then dies	Overload protection, shorted component	Disconnect cards and drives; test with minimal config
Fan spins but no startup	Dead PRAM battery, failed logic board	Replace PRAM battery; check for capacitor damage

**Startup Problems**
Symptom	Possible Cause	Action
No chime, no video	Dead logic board, failed capacitors	Recap logic board; check PRAM battery
Chime but no video	VRAM issue, video connector	Reseat VRAM SIMMs; check video cable
Sad Mac error	Hardware failure	Decode error code; test RAM
Flashing question mark	No boot device	Check SCSI drive; verify termination
Chimes of death	RAM failure	Reseat or replace RAM SIMMs

**Common Sad Mac Codes**
Code Range	Meaning	Action
01XXXX	ROM test failure	Check for corrosion; may need logic board repair
02XXXX – 05XXXX	RAM test failure	Try different SIMMs; clean SIMM slots
0DXXXX	NuBus card failure	Remove all NuBus cards
0EXXXX	SCSI controller failure	Check for capacitor damage
0FXXXX	Data bus failure	Logic board damage

See Sad Mac Error Codes for complete reference.

**Display Issues**
Symptom	Possible Cause	Action
No video after chime	VRAM failure, cable issue	Reseat VRAM; check video cable and monitor
Distorted or garbled	VRAM configuration, bad VRAM	Ensure matching VRAM SIMMs; try removing VRAM upgrade
Wrong colors	VRAM issue, video DAC	Reseat VRAM; check for capacitor damage
Flickering	Loose cable, monitor issue	Check video cable; test with different monitor

**Sound Issues**
Symptom	Possible Cause	Action
No startup chime	Audio circuit failure, capacitor damage	Recap logic board
Distorted audio	Failed capacitors	Recap logic board
No audio through jack	Jack issue, cable	Test with different cable/speakers

**CD-ROM Problems (if installed)**
Symptom	Possible Cause	Action
Drive not recognized	SCSI ID conflict, loose cable	Check SCSI ID (usually 3); reseat ribbon cable
Disc not reading	Dirty lens, worn laser	Clean lens with CD lens cleaner
Tray won't open	Mechanical failure, stuck tray	Use emergency eject hole (paperclip); lubricate mechanism
Audio CDs work but data CDs don't	Driver issue, laser calibration	Reinstall CD-ROM driver; laser may be failing
Slow performance	Dirty lens, failing drive	Clean lens; 2X drives are slow by design

The IIvx serial ports are limited to 57.6 kbit/s:

**Serial Port Problems**
Symptom	Possible Cause	Action
Modem connection fails	Speed limitation	Configure modem for 57.6 kbit/s or lower
MIDI timing problems	Port speed insufficient	Use external MIDI interface card
Printing slow or fails	Speed setting	Check printer driver settings

**Drive Problems**
Symptom	Possible Cause	Action
Flashing question mark	No bootable System	Check SCSI drive; verify cable; test with boot floppy
Drive not recognized	Wrong SCSI ID, termination	Verify unique SCSI IDs; check termination
System freezes during boot	SCSI bus conflict	Disconnect all SCSI; add one at a time
Floppy not reading	Dirty heads, failed drive	Clean heads; test with different disks