[comp.sys.mac] Static brushes

mo@seismo.CSS.GOV (Mike O'Dell) (11/13/86)

Folks, 
I hate to bring this up, but these statements
flying about that the static drain brushes
are unneed on disk drives is rather worrysome.

There are damn few things in this world as price-
sensitive as small winchester disk drives, particuarly
when it comes to something a Human must install
during assembly.  If the things REALLY weren't
needed, the disk builders would have LONG SINCE
stopped putting them on there.  Yes, they squeek,
and yes, one can lubricate them with just a speck
of graphite to make it much better.  But for all
you out there who wonder why the disk seems to 
develop bad spots over time after removing them,
or the drives get subtly more transient read,
or worse, write errors, it is because the
static is getting into the electronics.
Further, just what do you thing a healthy
discharge into the read preamp is going to do
to your drive?? Right - void the warranty in spades.

So, there are things to do short of  completely
ignoring the engineers who designed the thing
in the first place.  You can lube them,
'cause if you rip them off, you are asking 
for trouble. "Maybe not today, maybe not
tomorrow, but soon, and for the rest
of your life."

	Here's lookin' at your data,
	-Mike

brad@gcc-milo.ARPA (Brad Parker) (11/14/86)

> ... If the things REALLY weren't
> needed, the disk builders would have LONG SINCE
> stopped putting them on there.

Wouldn't it be nice if the world were so simple... Unfortunetly, it
seems (after many discussions with 3 1/2" disk drive vendors) that many
are not sure of the effect of removing the ground springs. These springs
are carried over from 14" winchester designs through 8" and 5 1/4"
winchesters. What's not clear is whether the spindle and platter assemblies
generate enough of a charge to warrant grounding. (it would be a bummer to
have the platter discharge through the head.) 

Anyway, my point is that many of the manufacturers seem confused about
the function of the ground spring on 3 1/2" drives. Most simply place
a small teflon pad on the spring to dampen the oscillation.

-- 

J Bradford Parker
General Computer (HyperDrive Beach, 3rd Cabana)
harvard!gcc-milo!brad

Good Sex is easier than a good slow roll. ("Left Stick! Right Rudder!...")