Power Macintosh 6500 Troubleshooting
Troubleshooting is essential for diagnosing and resolving issues with your Power Macintosh 6500. This guide covers common problems and their solutions.
Preliminary Checks
Before troubleshooting, verify:
- Power cable is securely connected
- Monitor is connected and powered on
- Keyboard and mouse are connected to ADB port
- No disks are in the floppy or CD-ROM drives during startup
No Power
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| 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 and PCI cards; check for capacitor leakage |
| Clicking or ticking sound | Power supply fault | Replace power supply |
| Powers on briefly then shuts off | Short circuit or thermal protection | Check for loose screws or debris; inspect for failed components |
Startup Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Chime but no video | Video circuit failure or RAM issue | Reseat RAM; test with different monitor; check VRAM |
| 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 hard drive connections; boot from CD-ROM; reinstall system |
| Sad Mac icon | Hardware failure | Note error code; see Sad Mac Error Codes |
| Gray screen with no boot | System software corruption | Boot from CD; reinstall system software |
Sad Mac Error Codes
The 6500 may display Sad Mac codes indicating hardware failures. See Sad Mac Error Codes for a complete reference.
Common codes:
- 0000000F / 00000001: RAM failure (check/replace RAM)
- 0000000F / 00000005: ROM checksum failure
- 00000003 / 00000001: Bus error during boot
RAM Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| System reports less RAM than installed | Bad DIMM or incorrect speed | Verify 60 ns or faster DIMMs; test each DIMM individually |
| Random crashes or freezes | Faulty RAM | Run memory test software; try known-good RAM |
| Death chimes at startup | RAM not recognized | Reseat or replace RAM; clean DIMM contacts |
Hard Drive Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Drive not recognized | Cable connection or drive failure | Check IDE cable; verify jumper settings; test drive externally |
| Slow performance | Failing drive or fragmentation | Back up data immediately; consider replacement |
| Clicking sounds from drive | Imminent drive failure | Replace drive immediately; attempt data recovery |
| "This disk is unreadable" | File system corruption | Run Disk First Aid; reformat if necessary |
CD-ROM and Zip Drive Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| CD-ROM not reading discs | Dirty lens or laser failure | Clean lens; check for disc damage; replace drive |
| CD tray won't eject | Belt slippage or mechanical failure | Use paperclip emergency eject; replace belt |
| Zip "click of death" | Drive head or media failure | Replace Zip drive; do not use affected disks in other drives |
| Zip drive not recognized | SCSI termination issue | Check internal SCSI chain; reseat drive |
Video and Display Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| No video output | Bad connection or video circuit failure | Check monitor cable; test with different monitor |
| Distorted or wavy display | Refresh rate mismatch or interference | Adjust monitor settings; move away from interference sources |
| Wrong colors or color banding | VRAM issue | Zap PRAM; check video settings in Monitors control panel |
| Video works only at low resolution | VRAM or video chip failure | Video subsystem may need repair |
Audio Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| No audio output | Muted or disconnected speakers | Check Sound control panel; verify speaker connections |
| Distorted audio | Bad capacitors or speaker damage | Recap if necessary; test with headphones |
| Crackling or popping | Capacitor failure | See Power Macintosh 6500 Capacitor Replacement Guide |
PRAM and Settings Issues
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
- Replace PRAM Battery: The 4.5V alkaline battery may be depleted
⚠️ PRAM battery
The Power Macintosh 6500 uses a 3.6 V 1/2AA lithium PRAM battery that leaks and can burst, corroding the logic board. Remove it from any un-serviced unit and clean/repair any leakage before troubleshooting.[1]
⚠️ Recap (logic board and PSU)
The Power Macintosh 6500 uses aluminium electrolytic capacitors on both the logic board and the power supply, and they leak with age. Recap and clean both boards as a first step; the large 2200 uF PSU filter capacitors in particular are a known failure point, giving a dead machine, failure to power on, or instability.[2]
References
- ↑ 68kMLA — Exploding Maxell PRAM Batteries. Source for the leaking/exploding 3.6 V lithium PRAM battery.
- ↑ Recap-a-Mac — Power Macintosh 6100; Badcaps "Macintosh 6100 power supply"; and the Apple Performa/Power Macintosh 6400/6500 Service Source. Source for the logic-board and power-supply electrolytic failures (including the 2200 uF PSU capacitors) and the recap.