amiga 4000 simm slots only addressing 1 meg per slot

[magnetic]

Its sounding more and more like a broken/bad trace somewhere. can u ohm them out from ram slots to chips and see? or u mentioned a scope,may be the ticket there.

please let us know what you find!

mech

This RAM Simm problem is very common and symptomatic of battery corrosion ruining traces near the slots as mechy says. Sometimes you cant see it because its deep in the layers of the board. Take the MB out and inspect it underneath and neutralize all corrosion/acid. changing CPU and/or buster makes no difference generally with Ram trouble.

[magnetic]

If jumper 852 is set correctly, you can try use larger simm in fast slots and chip slot and switch J213 and J213 to 8MB and try what change. I noticed, that in my Amiga, when using larger simm on original setting simm wasn't recognized correctly, when set those jumpers to 8MB my Amiga had 2MB chip and 16MB fast.

wow thats the first time i've heard of something like this..