AppleCD 150 Troubleshooting Guide
Fault-finding for the AppleCD 150 and the AppleCD 300, from Apple's shared Service Source and owners' repair reports. Apple's symptom charts list cures in order of likelihood: try the first, check whether the symptom has gone, and if not, refit the original module before trying the next.[1] The take-apart steps are on AppleCD 150 General Maintenance.
First checks
[edit | edit source]The drive needs a working SCSI chain and Apple's CD-ROM software on the Macintosh. Before opening it:
- Switch the drive on before the Macintosh, so that it is found at startup.[2]
- Check the SCSI ID is unique on the chain. Apple sets its CD-ROM drives to ID 3.[2][3]
- Check the terminators. Apple's external SCSI devices have no internal terminator, so the last device on the chain needs a cable terminator.[2]
- Check that the Apple CD-ROM extension is installed in the System Folder.[2]
- Try a clean, undamaged disc lying flat in the caddy, label side up. Apple's first cure for a drive that will not accept a disc is to exchange the disc.[1][3]
Service Source symptom chart
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Green power light is not on | Power supply; drive mechanism |
| Drive does not accept a disc | Replace the disc if it is dirty or damaged; drive mechanism |
| Headphone jack does not work correctly | Drive mechanism; power supply |
| Volume control does not work correctly | Drive mechanism |
| Speaker jacks do not work | Drive mechanism; audio-out assembly; power supply |
| Macintosh cannot mount the drive | Drive mechanism; power supply; SCSI-device-to-case cable; SCSI select switch |
The exploded view has no separate headphone board, and the chart's first cure for both the headphone jack and the volume control is the drive mechanism.[1]
Drive keeps ejecting the caddy
[edit | edit source]A drive that draws the caddy in and throws it straight back out, every time, is a known fault of the Sony caddy mechanisms used in these drives. On the CDU-541-25 of the AppleCD 150 it is caused by leaking surface-mount electrolytic capacitors on the drive's main board, and llamamusic.com reports the same fault on the CDU-535, CDU-561 and RRD42-AA.[4] Before recapping, rule out a disc that is not lying flat in the caddy; Apple's guides give that as a cause of discs being rejected.[3] Then follow the AppleCD 150 Capacitor Replacement Guide.
Caddy jammed
[edit | edit source]For the internal AppleCD 300i, which uses the same kind of caddy mechanism, Apple's procedure is to switch the computer off, straighten at least 3 inches of a large paper clip and push it firmly and horizontally into the pinhole below and to the right of the drive door. Apple warns that using the paper clip with the power on may damage the drive. If the next caddy then fails to load, shut down, wait about fifteen seconds and start up again.[3] On an external drive, switch the drive itself off before using the paper clip.[5]
No power
[edit | edit source]A green power light that stays off points first to the power supply, then the drive mechanism.[1] Check the mains fuse first: it is behind the rear panel and takes a type MT4, 250 V, 2 A fuse, which Apple does not supply as a service part.[1]
Drive not recognised
[edit | edit source]If the Macintosh cannot mount the drive after the first checks above, Apple's order is drive mechanism, power supply, SCSI-device-to-case cable, then SCSI select switch.[1] After fitting a new mechanism, check the SCSI select switch cable: it plugs onto the left four pairs of pins in the drive's connector with the looped wire facing the audio-out cable, and a new mechanism must have its jumpers over the left three pairs of pins removed first.[1] Do not fit an AppleCD 300 mechanism in an AppleCD 150 case; the SCSI-device-to-case cable will not connect correctly.[1]
On the AppleCD 300, some programs written for single-speed drives play jerkily or lose sound synchronisation at double speed. Set the drive to Standard Speed in the AppleCD 300 Speed Switch control panel.[3]
No audio
[edit | edit source]If the headphone jack or speaker jacks are silent, Apple's cures start with the drive mechanism; for the rear jacks the audio-out assembly comes next.[1] Herb Johnson notes that the AppleCD 150 may not pass CD audio to the Macintosh over SCSI; Apple lists that only for the 300.[6][7]
Related pages
[edit | edit source]- AppleCD 150
- AppleCD 300
- AppleCD 150 General Maintenance
- AppleCD 150 Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Apple Computer, AppleCD 150/300 Service Source, hosted as File:Applecd 150-300.pdf (see AppleCD 150/300 Service Source). Troubleshooting: General p. 1, Symptom Charts pp. 2-3; Take Apart, CD-ROM Drive pp. 4-8; Additional Procedures, Fuse pp. 1-2.
- ↑ 2.0 2.1 2.2 2.3 Apple Computer, AppleCD SC Plus Owner's Guide (1991), Appendix A, pp. 82-83 (PDF pp. 91-92), hosted as File:AppleCD SC Plus Owner's Guide (1991).pdf. Apple's troubleshooting advice for its external SCSI CD-ROM drives: power-on order, termination, unique SCSI ID, software installation.
- ↑ 3.0 3.1 3.2 3.3 3.4 Apple Computer, AppleCD 300i User's Guide (1992), Chapter 6, Troubleshooting, pp. 31-34 (PDF pp. 37-40), archive.org item AppleCD_300i_Users_Guide_1992; hosted as File:AppleCD 300i User's Guide (1992).pdf.
- ↑ llamamusic.com, "AppleCD 150 Caddy Eject Problem: PCB Capacitor Replacements", llamamusic.com/s50s550/AppleCD_150_Repair.html (retrieved 4 October 2026).
- ↑ Apple Computer, AppleCD SC Plus Owner's Guide (1991), Appendix A, p. 84 (PDF p. 93), hosted as File:AppleCD SC Plus Owner's Guide (1991).pdf.
- ↑ Herb Johnson, "Mac Hard and CD-ROM Drives, Technical info", Retrotechnology, retrotechnology.com/herbs_stuff/m_scsi.html (retrieved 4 October 2026).
- ↑ AppleCD 150/300 Service Source, Specifications, Characteristics 300, p. 4 (formats, including CD digital audio data via the SCSI bus).