29 Oct
2024
29 Oct
'24
12:26 p.m.
On Tue, Oct 29, 2024 at 7:10 PM Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
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.
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
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
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? 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