Capacitor Reference - Macintosh IIfx

The Macintosh IIfx's logic board is unique. The 14 47uf 16v surface-mount caps shown in the list below could be populated with electrolytic caps, tantalum caps, or a mix of both. There are actually two sets of pads for each of these caps, one designed for a tantalum cap, and another set designed for electrolytic caps. Note that seeing a mix of BOTH types is common. The most common mix seems to be a configuration of mostly all tantalums, but with 2 electrolytic caps near the battery holders. Make sure to check your board carefully to make sure you don't miss any electolytic caps.

One last important thing to check: If your IIfx has the C1 capacitor populated as a TANTALUM cap, it may have exploded, or may explode in the future. This is due to the characteristics of tantalum caps - a 16V rated cap is actually too low for a voltage rail that's running at around 12V. Using one in this way can cause a shortened lifespan. Check that it hasn't already exploded, and if it has, replace it with a higher rated 47uf 25v cap. See this forum thread for more info.

Logic Board

Reference Image

Click image below to view the full-resolution version.

Note: This IIfx had mostly tantalum caps populated from the factory. My red circles for the 47uf 16v caps are all over the location where there WOULD be electrolytic caps on a IIfx equipped with them. If these pads are unpopulated on your IIfx, you don't need to replace them. Many DO have a mix of both types though, so look carefully. A few of the pads highlighted on this board are populated. Those were replaced by MrFahrenheit, my guess being that they were populated with electrolytics on his board.


Page last updated (MM/DD/YYYY): 05/16/2024
Update Reason: links updated

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