Macintosh IIfx Issues

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

Capacitors

The Mac IIfx shipped with either tantalum or electolytic capacitors on the logic board. The first thing you should do when you get a IIfx is to check which type you have. Be warned though - most boards with tantalum caps will still have two elecrolytic caps in the power circuit. Any surface mount electrolytic cap in the system must be changed out, as the originals leak and will damage the board if left installed. In addition, capacitor C1, if a factory tantalum, is prone to exploding due to being slightly underrated for its application. It is recommended that this capacitor be changed out with one of a higher voltage rating to prevent this failure.

Capacitor reference information is available under the resources page, or directly through The Capacitor Reference Library.


PRAM Batteries required!

The Mac II, IIx, and IIfx all have two lithium batteries on the logic board, one for backing up the PRAM, and the other to run the soft power startup circuit. If the soft power battery is dead, the Mac IIfx won't turn on. Step two after inspecting for leaking capacitors should be to remove both original batteries, and to at least replace the soft power battery. The original ones have all mostly gone bad and they're very prone to leaking with age, despite being Lithium. Some brands are worse in this regard than others, but any original battery should be removed. They can cause terrible damage if left unchecked.


Other Notes

Power supply reliability is pretty good compared to other Mac II-series computers. They still can be a trouble spot as parts age though. Some of them used RIFA filter caps which are prone to expoding. Other capacitors can also grow weak with age, although the ones used in the Mac IIfx PSUs aren't especially known for failure.

Most 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.

The Mac IIfx'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 Macs from the 90s though.



Page last updated (MM/DD/YYYY): 04/20/2024
Update Reason: added newnav

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