20 Nov
1999
20 Nov
'99
8:13 a.m.
On Sat, 20 Nov 1999, Tony Duell wrote:
The only 24V DC spindle motor that comes to mind at the moment was on
the Tandon 848-02 DSDD half-height 8" drive, Tony.
- don
Re:
Ah... Most 8" drives do have mains-powered induction motors, so the
frequency does matter. I've seen reference to the odd drive with a 24V DC
spindle motor, but I've never seen an actual drive like that (although I
am sure they exist). If the motor 'looks' like a mains motor, has a large
capactor can hung off it, and seems to have mains wiring going to it,
then it's likely to be a mains motor. > I just received an IBM 5120, from Germany.
The back says 200/210/220 volts
> at 50 Hz. However, opening it up and looking at the power supply reveals
...
Well, I don't know this machine, but I can
make some general comments.
Firstly, it's normally safe to ignore the frequency differnce, at least
to start with. Most PSUs are equally happy with 50Hz or 60Hz. A _few_
...
That sounded good, until I read further:
The mains frequency may be important if AC motors
(like disk drive
spindle motors) are run off it, since the speed of induction motors is
because there are two 8" floppy drives in the same case. Also, most of the time, the drive spindle motors exist
in 115V and 230V
forms. A few machines always use 115V drives and run them of an
autotransformer (or the primary of the PSU transformer serving as an
autotransformer), but many of them expect you to have to have the right
drive for your local mains voltage. You might well have had to use an
external step-up transformer anyway....
As to the speed problem. I assume the drives are turning, albeit too
fast. Normally there were 2 motor spindle pulleys, one for 50Hz and one
for 60Hz, all other parts being the same. The 60Hz one was about 5/6 the
diameter of the 50Hz one (the speed of these motors is proportional to
frequency).
In which case you need to make a new spindle pulley. This is a pretty
easy job on a lathe -- if you don't have machine tools, try to find a
friend who does model engineering and who can make you such a part.
I bought a step up transformer and tried powering
up the system
yesterday. It wasn't a total failure. The monitor displays every other
character as a solid white box, and other every character as varying
junk (the junk varies while you watch). If you flip the display control
This is almost certainly another fault, not related to the mains
frequency problem.
-tony