[Coco] Re: Any problem with connecting 2 floppies to one power supply?
gene.heskett at verizon.net
Mon Feb 2 12:43:24 EST 2004
On Monday 02 February 2004 09:06, Amardeep S Chana wrote:
>"Gene Heskett" <gene.heskett at verizon.net> wrote
>in message news:200402012000.33788.gene.heskett at verizon.net...
>> That said, I did it for several years in my grass valley e-disk
>> simulation running on os9, but its duty cycle was quite low.
>> Never had a problem with it, ever, other than dying wd-1773's in
>> the disk controllers, it used up 3 of them in 13 years. I think
>> the purple plague ate them, a well known PMOS chip failure
>According to the data sheets, the WD chips were all NMOS even back
> to the 1771 single density parts.
You are probably correct. Didn't most PMOS parts need a substrate
bias of -5 to -12 volts? In which case these didn't need it. So
maybe the failure mechanism wasn't the plague, but there did seem to
be one as I've seen about 5 or 6 blown ones now. The 3 failures at
the tv station didn't seem to be static related while hooking up the
cables that I could see, but one of just sitting there powered up,
being used maybe 5 or 10 times a day, and the drives would suddenly
disappear. At which point I went chasing around to find yet another
of the short controllers because they were the only ones that would
fit inside a 19" racks width. The last time I had to extract a chip
from a long controller and transplant it. However, down thru
history, the lack of a decent line cord, no third pin ground on any
of that stuff, no doubt did contribute to some failures. I'm pretty
sure I blew one here at home from that effect back before I'd put my
whole system on a single pc power supply.
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Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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