More on the Commdore D9090 hard drive with pics:
I have given up trying to find a 6-head Tandon 603s, and I decided to use a 4-head ST-225 because they are easier to find. I used a B-128 to format the drive.
1) On the controller (top) I snipped J14 jumper to make the D9090 think it was a D9060. This modification is necessary because the D9090 controller is set to use a 6-head drive. Clipping J14 converts the controller into a de-facto D9060 which expects a 4 head drive. The D9060 came with Tandon 602s.
2) I removed the Tandon 603s hard drive that originally came with the drive, reassembled w/o cover.
3) ran a quick test to be sure that the drive was put back together safely:
> ?ds$ [enter]
73, CBM DOS 3.0.0 etc
4) I used the following command:
>header "degnan",d0,i01 [enter]
Are you sure? y [enter]
5) Both drive lights came on solid green, no visible flashing, and I was no longer able to type at the computer.
6) I looked inside the drive at the light of the ST-225, also solid
7) I listened closely, heard nothing other than the drive spinning. A stethoscope would have been useful here.
8) After about 15 minutes I noticed that the drive light would flick once every 10-20 seconds, and the drive would simultaneously click very softly.
9) Left room, had dinner
10) Came back about ~45 minutes later, the drive had returned control to the computer.
11) ran a DIRECTORY command
19441 blocks free
12) The Tandon 603S sits "higher" than the ST-225. As a result I need to use taller risers on the back two posts, and for the front two posts I need slightly taller again front risers.
..geez I think I went through 10 drives before I found a working drive (by first testing in an IBM XT). Hopefully this will help people in the future with the same project. There isn't really anywhere on the web that clearly explains the process of replacing the Tandon 603s brick with the ST-225.