Macintosh LC III and III+ - Common Faults & Maintenance

From leaking batteries to bad capacitors, Mac LC IIIs require maintenance to remain in good working order. Read below to find out about what issues may need addressing.

Capacitors

The Mac LC III has many surface-mount (SMD) electrolytic capacitors on its logic board. These capacitors have a 100% failure rate and will leak a corrosive and conductive electolyte fluid over the board that will damage components and traces given enough time. These capacitors must be replaced for continued operation of any Mac LC III. Capacitor reference information is available under the resources page, or directly through The Capacitor Reference Library.

The LC III's Power Supply can also be problematic. They shipped with supplies from three vendors - Astec, TDK, and Dyna Comp. All three can be prone to bad or leaking capacitors, but the TDK unit is the worst of the three. It used ELNA LongLife series caps which are probably the most leak-prone through hole caps from the time. These can cause a real mess, so any TDK PSU is a recap on sight. The Astec supplies are better but still can experience issues. Recap if you're having power trouble. The Dyna Comp unit also has cap leaks but I don't know how common they are.


PRAM Battery Leaks!

The Mac LC III uses a 1/2AA size Lithium battery for PRAM backup. This battery is not required on the LC III for operation, and any original battery should be removed. These original batteries often leak, and can cause catastrophic damage that renders logic boards unfixably damaged.


Other Notes

Many original SCSI hard drives for these have gone bad, especially those made by Quantum, which suffer from sticky rubber bumpers in the head assembly.

The floppy drives in these often suffer from eject motor failures due to a gear that falls apart with age. This gear can be replaced without too much trouble. They also suck in tons of dust, so a good cleaning is in order for just about any unserviced unit.

The Mac LC III's case yellows with age. A retrobrite process can be used to correct this, if it bothers you. The plastic is not nearly as brittle as later models though.



Page last updated (MM/DD/YYYY): 04/19/2024
Update Reason: added newnav

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