Trying to call my A4000D back to life

[spirantho]

Possibly a Chip RAM problem...? If it works ok with Fast RAM (at least at first) then it'll be using less Chip RAM. Do a memory test on the Chip RAM (there are various memory test programs on Aminet) - and Fast RAM too for that matter. It's possible one of the addressing lines is dodgy.
Have you tried booting a game?

[spirantho]

I think you'll be ok on the VIA connections....

For the sockets, this page is your friend:
http://www.amigawiki.org/doku.php?id=en:service:schematics

The schematics on this page are simply awesome (and searchable). If it didn't always identify all the Fast RAM that sounds like something dodgy that could be a more serious problem.

[spirantho]

The purpose of the RAM test is less to check the RAM and more to check the connections to the RAM. Testing in another machine won't help here.
The purpose of a game test is just to rule out as many variables as possible (bad floppies etc.) - if a simple 512KB A500 game (Which is tested as normally working on an 040) fails, it'll give us a bit more idea. Still sounds like a bus error to me.

That thing about only 8MB RAM detected.... I presume you're fitting 4 4MB SIMMs? If it's supposed to be 16MB but only 8MB is detected, then something's squiffy with the RAM bus or connector, probably.

[spirantho]

How does it behave with all the Fast RAM removed? Does it work like with the A1200 or is still unstable?

[spirantho]

I meant how does it run with the A4000 ROMs and no fast RAM? Very unlikely indeed it's your ROMs at fault.