On Tue, Oct 29, 2024 at 7:10 PM Fred Cisin via cctalk <cctalk@classiccmp.org> wrote:
> > I've never seen a 5.25" or smaller floppy drive with a mains > > sychronous motor. > Nor I. I don't recall ever seeing a 5.25", 3", 3.25", nor 3.5" that used > anything other than 5VDC and/or 12VDC Nor have I. On the other hand there are Archive tape drives that used +5 and +24V with the same power connector as a 5.25" floppy drive. Thankfully they kept the 5V and grounds in the same place. I am told some Sun machines had power cables for both disk drives and said tape drive, the only difference was the colour of the wire (yellow for 12V, orange for 24V) Sounds like a source of magic smoke emission. > > Almost all of the 5.25" (and, I think 3") used the same "molex" connector. Certainly the Panasonic (used by Amstrad, 26 pin header for the signals) and Hitachi (34 pin edge connector for the signals, same as a 5.25" drive) 3" drives used the same AMP power connector as the 5.25" drive, pins in the same order. I forget who made the drive in the Tatung Einstein but that was the same power connector too. > I have a 3.25" drive that uses the same connector as 3.5", BUT different > postions for the voltages! ARGH! > > > As an aside, Tektronix used normal 8" drives in some of their > > machines, always fitted with 60Hz pulley sets. They produced a 115V > > 60Hz output in the power supply, frequency contolled by a crystal. As > > a result said machine would run off 50Hz mains, 60Hz and indeed 400Hz > > aircraft supplies without pulley changes > > How much 115VAC power do they produce? Well enough to run a couple of normal 8" Drives. Nothing more, the rest of the electronics including the micropolis hard disk (which can replace one of the floppy disks), DEC 11/03 or 11/23 CPU board and all the Tektronix memory and I/O boards run off the DC outputs of the switch mode PSU > Because one couldn't supply drives with an asterisk? Well the Qumetrak 142 drives have 'IBM' moulded nto the panel so presumably the could have had the asterisk as well. > or because they didn't want to use the crappy Qume 142 drives on anything > else? > The Qume 142 was so slow stepping, that that was one of the reasons for > introducing PC-DOS 2.10, to have a slower step time. Hmm. It's strange, it looks like the thing double-steps. There are some monostables to generate a second step pulse a bit after the normal one. The Qume manual says they can be modified for 6ms step rate but doesn't say how, The IBM TechRef says their 'slimline' drive runs at a 6ms step rate. I've just stripped and cleaned a pair of the IBM-badged ones (ignore the Qume manual, there are better ways to do it!). I've had them on an exerciser and they work reliably at 6ms step rate. -tony
