How to Repair a Failed Avant Stellar Keyboard EEPROM
Restore Your Keyboard Functions to Like New
The Avant Stellar keyboard, which is a continuation of the famous Northgate mechanical switch PC keyboards, is a joy to use. It contains Alps key switches which have a wonderful tactile 'click' feedback - way superior to the mushy sponge switch keyboards typically sold these days.
The Avant Stellar has an improvement over the original Northgate keyboards: it is programmable! This means, among other things, that you can relocate the key positions. Specifically, you can move the control, alt, and caplocks keys back to the original IBM keyboard positions. The original keyboard package even included extra keycaps to facilitate this. The problem is, the EEPROM which holds the keyboard layout tends to fail with age.
One would normally think that a failed memory chip would spell the end of the keyboard, but this is not the case. When the EEPROM fails, key functions become completely random and thus, the keyboard becomes useless. But by removing the memory chip, keyboard function is restored - except the key layout reverts back to the factory original locations. This is nice, as your keyboard becomes functional again, but all key remappings are lost. As I am used to the modified locations (I use the CTRL key extensively, and never use CAP LOCK), this was not acceptable.
It turns out, the memory chip, a FM24C16, is still available from DigiKey as a FM24C16-R, in a surface mount package (SOIC-8). The original DIP-8 package is discontinued. I had no idea if one could simply install a new chip and have it work, so I orderes a couple chips (under $3 each) to gave it a try. Turns out it works fine!
For this repair, after removing the failed EEPROM, I replaced it with a DIP-8 socket (in case the fix didn't work, I could simply unplug it). I carefully mounted the new chip onto a DIP-8 header connector. [In retrospect, I would use a readily available SOIC-8 to DIP-8 prototype board, but I didn't have one and didn't think to order one. But it worked out fine.]
FM24C16-R Mounted on Header
Header Installed on Keyboard
After completing the repair, connect the keyboard to your computer. Using the keyboard programming key sequence (info in the keyboard manual ), perform the erase/reset sequence to initialize the new memory chip.
