The Macintosh Classic was released in 1990 and ran until 1992, though runs the same 8MHz Motorola 68000 found in the earlier Macintosh Plus and Macintosh SE models. Similar to the SE model, the Classic has room for an internal hard disk. The Classic wasn't an overly remarkable computer, but we believe it was designed to be a low cost solution ideally for the education market. As a result, the Macintosh Classic was commonly found in schools during the early to mid 1990s.
Secret ROM Disk
There is an embedded copy of Apple System 6 stored in the ROM. Hold down Command + Option + X + O during power-on to boot off the ROM disk.
- Due to the age of this computer, modern usage requires the logic board have the capacitors replaced and the PRAM battery removed or replaced. Capacitors on the analog board may also need to be replaced if you experience issues with the display.
- Another potential Classic issue is the failure to complete the "POST" sequence and the system will stop loading just before the point where the "happy Mac" or blinking disk icon would show up. We suspect this is the result of a defective SCSI bus.
Analog Board Voltage
Some tips on modifying Mac Classic Analog Boards! ------------------------------------------------- If you want to modify a Mac Classic from 110v to 240v (or vice versa) use these tables: Late Revision Classic Analog Board (JP2 marked on PCB across CP13 location) 110v 240v JP1 Wire Link - JP2 - Wire Link CP1 220uF 250V 220uF 400V CP13 220uF 250V - CP19 4.7nF 250V 10nF 250V <-- Must be Class Y Rated CP38 Wire Link 10nF 250V <-- Must be Class Y Rated Early Revision Classic Analog Board (JP2 not marked across CP13) 110v 240v JP1 Wire Link - CP1 220uF 250V 220uF 400V CP13 220uF 250V 220uF 400V CP19 4.7nF 250V 10nF 250V <-- Must be Class Y Rated CP38 Wire Link 10nF 250V <-- Must be Class Y Rated
The SMD capacitors on the logic board will most likely have already started leaking electrolyte out the bottom, and failing to replace them in a timely manner will result in further leakage with possible damage to nearby components. See below list of capacitors to replace:
- 7 x 47uf 16V
- 1 x 1uf 16V
- https://archive.org/details/TheDeadMacScrolls - Troubleshooting/repair information for compact Macs