Sure you have the 4040 (have 4 simms slots, made for 4000) instead of the 4030 (2 simm slots, made for 3000)?
The 3000 version has a Int fix via a wire you can connect to your cia chip, which is quite easy and will save you the time of soldering your Motherboard. The 4000 version does not and you will need to make the INT correction yourself. You need to have this for SCSI to work. To hack your 3000 motherboard see
http://vgr.com/int2/ for instructions. That should fix your problem.
Here are the jumper settings:
TP1: Reserved.
TP2: Reserved.
JP1: SCSI Termination Power.
JP2: A Mode Select - Off: 040 Active On: 040 disabled.
B: SIMM Bank Size - Off:Dual Sided. On Single Sided.
C: SIMM Size - Off 16MB On 4Mb
D: Wait State - Off: no wait state On: Wait State.
E. Reserved.
F: MMU disable- Off: MMU enable on: MMU Disabled.
G: Cache diasable Off: Caches enabled.
H: SCSI config jumper
J: SCSI config jumper
K: SCSI config jumper.
L: Reserved ON.
JP3 Reserved.
JP4 Wire Clip for a3000 Version.