RA81 14" SDI Disk Drive

The top unit in the vax is an RA81 SDI disk drive. It's huge... 14 inche platters are BIG.

When you switch it on about 4 fans start up, at least some of them are 240v fans and they make an increadible noise. The RA81 drive is apparently 450MB with 14" platters. However someone has crossed out the "1" and written "2" in vivid. The RA82 is 650MB, which would be a significant score!

We eventually found out how to open the top. You have to turn the two allen bolts at the front bottom about half a turn each and then the top, including the front panel, lifts up.

Inside is a HUGE drive assembly with 10 or 12" disks inside a large black casing with a transperant front panel. The platters are driven by a seperate motor connected via a belt. The motor looks like it is an AC 240v motor and it gets VERY hot. The lid is held up by a gas strut, which was not at all expected. The drive contains a good sized circuit board on the mechanisim itself, and two boards that fold down from the lid and occupy nearly the entire lid serface area each. These two boards have their own pair of fans!

Initially we couldn't get it to start. The red fault light just lit up and the other lights flashed and it wouldn't do anything. I eventually found this to the wire on the right hand side. In the above picture you can see a wire with a plastic covered loop on the end that curls from the bottom of the right hand wall around a clip and is held some why back from the front of th unit. This wire runs around a pully behind the motor at the back of the unit and forward, over a gate with a microswitch that isn't resolved very well by the camera. The wire is sprung, and you pull it so a tag in the wire passes the gate and then pull it down into the gate where the tag holds it by spring tension. We didn't have it quite at the bottom of the slot and it wasn't operating the microswitch.

Once we closed the microswitch it would start. This is an even more increadible noise. It spins up and the ready light comes on. We once tried booting the vax from whatever is on the drive, and got VMS 5.5 to boot, however after about a minute, it failed and dropped us back to the preboot prompt.

copyright 2001 Tom Parker - last modified 26 Mar 2001