Macintosh Centris 660AV Troubleshooting
Troubleshooting the Macintosh Centris 660AV (also sold as the Quadra 660AV) requires understanding its unique architecture, including the AT&T DSP and GeoPort features. This guide covers the most common problems and their solutions.
Preliminary Checks
Before detailed troubleshooting:
- Verify the power cable is firmly connected
- Check that the power outlet is working
- Ensure all cables (keyboard, mouse, monitor) are properly seated
- Remove any recently added RAM or expansion cards
- Reset PRAM (Cmd-Opt-P-R at startup, hold through three chimes)
- Reset CUDA (remove power and PRAM battery for 10 minutes)
No Power
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| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Dead, no LED | Power supply failure | Check power cable; test outlet; inspect PSU for dust buildup on filter mesh |
| Dead, no LED | PRAM battery dead | Replace 3.6V half-AA lithium battery |
| Ticking sound | Power supply fault | Check for shorts on logic board; inspect capacitors; test with known-good PSU |
| Powers on briefly, then off | Short circuit | Remove all cards and RAM; test with minimal configuration |
| Fan spins but no boot | Logic board failure | Check for capacitor leakage; inspect for corrosion |
No Video
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Chime but no video | PRAM battery dead | Replace battery (common issue on 660AV/840AV per Apple KB TA35928) |
| Chime but no video | VRAM failure | 660AV VRAM is soldered; board repair or replacement required |
| Chime but no video | Monitor cable issue | Test with different monitor and cable |
| Garbled display | VRAM failure | Test with external video card if available |
| No video to TV/VCR | Video mirroring unsupported | This is normal; 660AV does not mirror to TV (monitor goes blank during video output) |
Tip: Hold Cmd-Opt-T-V during startup to force the Mac to use a TV as a monitor.
Chime Codes and Startup Issues
| Sound | Meaning | Action |
|---|---|---|
| Normal chime | Hardware OK | Issue is software or peripheral |
| No chime | RAM failure or no power | Check power supply; reseat/test RAM |
| Broken chime | RAM failure | Reseat or replace RAM SIMMs |
| Series of tones | Hardware diagnostic failure | Count tones; refer to Apple service codes |
Intermittent Booting or Freezing
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Random freezes | Failing capacitors | Inspect logic board for leakage; recap if needed |
| Freezes after warmup | Thermal issue | Clean dust; check fan operation; reseat chips |
| Freezes during disk access | SCSI termination issue | Verify internal drive is terminated; check SCSI ID conflicts |
| Freezes with extensions | Software conflict | Boot with Extensions Off (hold Shift); isolate problem extension |
Sad Mac Error Codes
The 660AV displays Sad Mac codes in the format XXXXXXXX / YYYYYYYY where the first number indicates the error class.
| First Digit(s) | Error Type |
|---|---|
| 01 | ROM test failed |
| 02 | Memory test – bus sub-test failed |
| 03 | Memory test – byte write failed |
| 04 | Memory test – addressing failed |
| 05 | Memory test – pattern failed |
| 0F | Reserved for internal use |
See Sad Mac Error Codes for a complete reference.
Audio Problems
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| No sound | Muted in Sound control panel | Check volume setting |
| No sound | Capacitor failure | Inspect and recap logic board |
| Distorted sound | Failing capacitors | Recap logic board |
| PlainTalk not working | DSP issue | Reinstall system software; check DSP chip |
GeoPort and Modem Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| GeoPort adapter not recognized | Driver issue | Reinstall GeoPort software |
| No dial tone | Adapter not connected properly | Check cable; try other GeoPort |
| Poor modem performance | DSP load | Close other applications using DSP |
Video Capture Problems
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| No video input | Wrong input selected | Check Video control panel settings |
| Grainy capture | Poor signal | Use S-Video instead of composite; check cables |
| Dropped frames | Slow hard drive | Use faster SCSI drive; reduce capture resolution |
| Audio/video sync issues | Buffer settings | Adjust capture software settings |
Floppy Drive Issues
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| Cannot read disks | Dirty heads | Use cleaning disk; clean heads manually |
| Disk eject failure (auto-inject) | Mechanical wear | Lubricate mechanism; replace drive |
| Cannot write to disks | Write protect tab | Check disk; try different disk |
| Disks not recognized | Drive failure | Replace floppy drive |
See Macintosh Floppy Drive Maintenance for detailed drive service procedures.
SCSI Problems
| Symptom | Possible Cause | Recommended Action |
|---|---|---|
| External device not found | Termination issue | Only terminate last device in chain |
| Device conflict | Duplicate SCSI ID | Assign unique IDs (internal drive is usually 0) |
| Slow performance | Cable quality | Use high-quality shielded cables |
| Intermittent device | Loose connection | Check and reseat all SCSI cables |
Software Compatibility
- System 7.5–7.5.3: The Startup Disk control panel is incompatible with Quadra AVs. Upgrade to System 7.5.5.
- 24-bit addressing: Not supported. Ensure 32-bit mode is enabled.
- PowerPC upgrades: Require a "fat" (universal) system installation.
- Mac OS 8.1: Maximum supported version without PowerPC upgrade.
- Mac OS 9.1: Supported with PowerPC upgrade card installed.
⚠️ PRAM battery — remove it now
The Centris 660AV carries a 3.6 V 1/2AA lithium PRAM battery. These leak and can burst, spraying corrosive electrolyte across the logic board and destroying nearby components — often while the machine simply sits in storage. Remove the PRAM battery from any un-serviced unit. If one has leaked, neutralise and clean the residue and repair corroded traces and vias before troubleshooting.[1]
Logic board (tantalum capacitors)
Unlike the LC and Mac II surface-mount-electrolytic boards, the 68040-family Centris 660AV logic board uses tantalum capacitors, which do not leak with age — the logic board does not normally need recapping. If the board misbehaves, look to leaked-PRAM-battery corrosion, socket/connector contacts and the power supply rather than to board capacitors.[2]
Power supply
The power supply uses electrolytic capacitors that fail with age (fails to power on, unexpected power-off, clicking when plugged in). Recap the power supply and confirm the rails.[3]
AV features
The Centris 660AV adds the AT&T DSP3210 digital signal processor and video in/out. If the machine boots but AV functions (video capture/out, enhanced sound) fail, confirm the AV software/extensions are installed and check the DSP and the AV connector before suspecting the main logic.
References
- ↑ "Warning! Exploding Maxell PRAM Batteries", 68kMLA; and MacDat — Macintosh II family. Source for the leaking/exploding lithium PRAM battery that destroys nearby components.
- ↑ "Apple Macintosh Quadra 650", Retro Viator; and the Apple Macintosh Quadra/Centris 650 Service Source. Source for the 68040-family logic boards using tantalum capacitors (no logic-board recap needed) while the power supply uses electrolytics that do need replacing.
- ↑ "Compact/Desktop Power Supply Capacitor Lists (by make and model)", 68kMLA; and "Capacitor Replacement in a Vintage Power Supply", Big Mess o' Wires. Source for the shared desktop PSU form factor (IIci/IIcx/IIvi/IIvx/Performa 600/Quadra 650/Quadra 700), the electrolytic failure symptoms and the PSU capacitor lists.