This is an old post, preserved for reference.
The products and services mentioned within are no longer available.
Every now and then, I get a message along the line of 'I've just installed your upgrade in my broken computer and it is still broken' (also sometimes phrased as 'I just installed your upgrade in my untested machine and now it is broken'). I offer to help where I can. In this case, it was one of my Atari 400 48K RAM upgrades. The owner sent in the main board and CPU board from his 400, along with the 48K RAM upgrade board he had built from the kit.
2022 Update: This sort of thing happened a lot with the Atari 48K RAM board. In every case as far as I can see, it was the Atari that was faulty in one way or another, not the RAM board. After I refunded several rather rude customers I discontinued the product to avoid further issues. Sorry to all the nice people in the Atari community who missed out. Blame the less polite members of your community and their pre-broken machines.