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From: bane@parcvax.UUCP
Newsgroups: comp.sys.atari.st
Subject: BMS-100, Adaptek 4000, Quantum 540 "feature"
Message-ID: <329@parcvax.Xerox.COM>
Date: Wed, 27-May-87 15:39:25 EDT
Article-I.D.: parcvax.329
Posted: Wed May 27 15:39:25 1987
Date-Received: Sat, 30-May-87 00:39:39 EDT
Organization: Xerox PARC
Lines: 28
Keywords: Interference, shielding

I recently spent an interesting evening in the offices of Berkeley Microsystems.
I was having trouble getting their board set to run a Quantum Q540 hard disk;
the disk would format and run, but with a huge number of bad blocks (3 meg
short out of 36). Since I live within 30 minutes drive of them, they told me to
come on up with my hardware and they'd get it running.

After about two hours of playing with various drives, controllers and interface
boards they had laying around, they discovered that the drive was sending out
some sort of electronic interference whenever it moved its heads, which the
Adaptek was picking up as bad blocks. The BMS folks had suspected this problem
with other customers before, but this was the first time they had seen one fail
so thoroughly and repeatably. The fix is straightforward, fortunately:

	DDDDDDDDDDDDDD
	DDDDDDDDDDDDDD	<- Quantum Q540 drive
	DDDDDDDDDDDDDD
	D            D
	--------------	<- Shielding (clad PC board or metal plate works fine)
Nylon ->S            S
stand-  AAAAAAAAAAAAAA	<- Adaptek 4000 controller
offs  ->S            S
	BBBBBBBBBBBBBB	<- BMS 100 interface board

I have no connection with BMS other than as an extremely satisfied customer.
-- 
	Rene P.S. Bane
	bane.pa@xerox.ARPA
	...!parcvax!bane.UUCP