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
| Value | Count | Type |
|---|---|---|
| 1000uf 10v | 1 | Axial Electrolytic |
| 470uf 16v | 3 | Axial Electrolytic |
| 220uf 16v | 1 | Axial Electrolytic |
| 47uf 16v | 14 | Surface-Mount Electrolytic |
| 10uf 16v | 1 | Axial Electrolytic |
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.
