On 02/18/2018 09:34 AM, P Gebhardt via cctalk wrote: > Hello list, > > currently, I am in the process of trying to bring back to life a disk drive > installation from Control Data known as "841 Multiple Disk Drive" ( MDD ). > From the early '70s. It uses hydraulic disk head actuators! Pictures of the > subsystem are here: > > http://www.digitalheritage.de/peripherals/cdc/841/841.htm > > I started with the power supply. Most of the electrolytic capacitors need to > be reformed which is being done. > As far as I know, some computer installations used 400Hz 3-phase back in the > days. Does anybody know, if that is the case for this type of drive systems? > I couldn't find any indication so far, except for the input filter that > supports up to 400Hz (written on it). > I've quite some experience with old linear power supplies, but never worked > with three-phase supplies, yet. > Has anybody experience with this? Anything particular to be considered? > > There is an operator's manual, but there don't seem to be manuals or > schematics about this type of CDC drive nor on bitsavers, neither elsewhere > on the net. How could help me in pointing out where to get these? > A lot of questions, I know.... :)
The claim about the "only CDC disk drive with hydraulic positioner" is false. Starting with the Bryant 6603, I believe that the 808 and very rare 821 also used hydraulics. Voice-coil positioners started to be used with the 844 drives. I don't recall what the 854 used, as it wasn't very common on big CDC iron. --Chuck
