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Saved another IIfx


Well-known member
A rough looking IIfx popped up on eBay US with extraordinardly cheap postage to Europe so I took a gamble. I probably spent more than I should have for a non-working machine, but it's a IIfx so... I couldn't resist.

I couldn't see the PRAM batteries directly and the machine was very dirty so there was a chance it was battery bombed.

It arrived today and thankfully the batteries hadn't exploded. It still had the original Tadirans from May 1990.

Two caps, C9 and C24, were leaky electrolytics, the rest tantalum. I replaced C9 and C24 with tantalums and cleaned the area around them.

Hooked everything up, applied power and ... nothing, even with fresh batteries.

Tried a different known working IIfx PSU, still no go.

I immediately thought it must be the startup circuit. Checked the schematic, and quite early in the startup process there should be continuity between R4 and R23 - well on my board there wasn't. Patched that and ...

Yep, it now works!

This is what the board looked like before I touched it:


The board was pretty dusty and grotty:


After cleaning and patch wire added:


20MB RAM! Someone back in the day meant serious business. Luxury compared to my other IIfx which came with 8MB RAM.



Well-known member
Just great to see these kinds of threads over and over. The more that work, the more will survive!


Well-known member
The Ethernet card in the machine is a bit different to my others. It has its own FPGA, onboard memory and a cartridge fuse. It's a Cabletron card from 1991.