Troubleshooting is essential for diagnosing and resolving issues with your Power Macintosh 6100. This guide covers common problems and their solutions.
Before troubleshooting, verify:
- Power cable is securely connected
- Monitor is connected to DB-15 port and powered on
- Keyboard and mouse are connected to ADB port
- No disks are in the floppy or CD-ROM drives during startup
- SCSI chain is properly terminated (if external devices connected)
Power Issues
| Symptom |
Possible Cause |
Recommended Action
|
| No response when power button pressed |
Failed power supply |
Check power outlet; test with known-good cable; inspect PSU capacitors
|
| Power light on but no startup |
Logic board failure |
Reseat RAM; check for capacitor leakage; reset CUDA
|
| System powers off unexpectedly |
Overheating or PSU failure |
Clean dust from vents; check fan operation; inspect capacitors
|
Startup Problems
| Symptom |
Possible Cause |
Recommended Action
|
| Chime but no video |
Video circuit failure or RAM issue |
Reseat RAM; test with different monitor; check video port
|
| No chime, no video |
Dead logic board or RAM failure |
Remove all RAM and test; reset PRAM (Cmd+Opt+P+R)
|
| Flashing question mark |
No bootable system found |
Check SCSI drive connections; verify SCSI termination; boot from CD
|
| Sad Mac icon |
Hardware failure |
Note error code; see Sad Mac Error Codes
|
| Death chimes |
RAM or ROM failure |
Reseat or replace RAM; test each SIMM pair individually
|
The 6100 may display Sad Mac codes indicating hardware failures. See Sad Mac Error Codes for a complete reference.
Common codes:
- 0000000F / 00000001: RAM failure
- 0000000F / 00000005: ROM checksum failure
- 00000003 / xxxxxxxx: Bus error
Memory Problems
| Symptom |
Possible Cause |
Recommended Action
|
| System reports less RAM than installed |
Bad SIMM or mismatched pair |
SIMMs must be in matched pairs; test each pair
|
| Random crashes or freezes |
Faulty RAM |
Run memory test software; try known-good SIMMs
|
| Death chimes at startup |
RAM not recognized |
Reseat SIMMs; clean contacts; verify 80 ns or faster
|
SCSI Problems
| Symptom |
Possible Cause |
Recommended Action
|
| Drive not recognized |
Termination or ID conflict |
Verify SCSI termination at end of chain; check unique SCSI IDs
|
| Slow performance |
Cable or termination issues |
Use quality SCSI cables; proper termination
|
| Clicking sounds from drive |
Imminent drive failure |
Back up data immediately; replace drive
|
| External devices not seen |
Termination or power issue |
Only terminate at end of chain; verify external device power
|
- Internal drive should NOT be terminated (the logic board provides termination)
- The last device in any external chain MUST be terminated
- SCSI IDs must be unique (0-6, with 7 reserved for the Mac)
- Internal hard drive typically uses ID 0
Display Problems
| Symptom |
Possible Cause |
Recommended Action
|
| No video output |
Bad connection or video circuit failure |
Check monitor cable; test with different monitor
|
| Distorted display |
Refresh rate mismatch |
Adjust monitor settings; use correct adapter if needed
|
| Limited resolution options |
No dedicated VRAM |
Integrated video limited to 640 KB; add NuBus video card for better resolution
|
Sound Problems
| Symptom |
Possible Cause |
Recommended Action
|
| No audio output |
Muted or wrong output selected |
Check Sound control panel; verify speaker connections
|
| Distorted audio |
Bad capacitors |
Recap if necessary; test with headphones
|
| No startup chime |
Logic board or speaker issue |
Check internal speaker connection; may indicate deeper problem
|
If the system loses settings, displays wrong date/time, or has unusual startup behavior:
- Reset PRAM: Hold Cmd+Option+P+R during startup until you hear a second chime
- Reset CUDA: Press the CUDA reset button on the logic board (small button near battery)
- Replace PRAM Battery: The 3.6V lithium battery may be depleted
DOS Card Problems
| Symptom |
Possible Cause |
Recommended Action
|
| DOS card not recognized |
Card not seated properly |
Reseat the NuBus card
|
| Windows won't start |
RAM or configuration issue |
Check DOS card RAM; verify DOS/Windows installation
|
| No video in DOS mode |
Monitor adapter issue |
Use correct adapter; check PC Setup control panel
|
