SCSI problem on 2000XL

My 2000XL just all of a sudden will not recogonize any external device connected to it. I purchased a new scsi cable and still the same problem. I found a MPC site and it said it was the SCSI fuse. I had a service tech look at it and he said the fuse was good. Anybody that has had this problem get at me so I can get it fixed. I live in Houston and can't find any service to get it repaired.

Is the last Devise in your SCSI-Chain terminated?
Make shure that there is a termination connector pluged, or there is a knob to switch the termination on or off.

Good Luck.