From owner-freebsd-hackers Mon Dec 6 11:53:38 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from uni4nn.gn.iaf.nl (osmium.gn.iaf.nl [193.67.144.12]) by hub.freebsd.org (Postfix) with ESMTP id A58D414E86 for ; Mon, 6 Dec 1999 11:53:31 -0800 (PST) (envelope-from wilko@yedi.iaf.nl) Received: from yedi.iaf.nl (uucp@localhost) by uni4nn.gn.iaf.nl (8.9.2/8.9.2) with UUCP id UAA31703; Mon, 6 Dec 1999 20:19:28 +0100 (MET) Received: (from wilko@localhost) by yedi.iaf.nl (8.9.3/8.9.3) id UAA01101; Mon, 6 Dec 1999 20:06:26 +0100 (CET) (envelope-from wilko) From: Wilko Bulte Message-Id: <199912061906.UAA01101@yedi.iaf.nl> Subject: Re: Strange SCSI sickness In-Reply-To: from Matthew Jacob at "Dec 5, 1999 2:42:55 pm" To: mjacob@feral.com Date: Mon, 6 Dec 1999 20:06:26 +0100 (CET) Cc: kbyanc@posi.net, jkh@zippy.cdrom.com, dseg@texar.com, billf@chc-chimes.com, rfg@monkeys.com, freebsd-hackers@FreeBSD.ORG X-Organisation: Private FreeBSD site - Arnhem, The Netherlands X-pgp-info: PGP public key at 'finger wilko@freefall.freebsd.org' X-Mailer: ELM [version 2.4ME+ PL43 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG As Matthew Jacob wrote ... > > > Another interesting cause for problems is duff powersupplies. As the > > proverb goes "every machine is as good as it's PSU". E.g. I just struggeled > > with a DLT tape unit that inexplicable reset itself. After examining the > > 5Volts rail with a scope I found glitches on it whenever the drive did a > > bit of rewinding (dropping out of streaming mode). Had me stumped for a > > while. > That's pretty rare these days. It used to happen all the time when > switching power supplies first appeared (motorboating is what we called > it), but even recently I had a marginal supply that supplied 4.4VDC- > *just* enough to function *most* of the time. This was a DLT4500 5 cartridge changer. I've seen multiple failures similar to this one due to degraded electrolytic output caps that made the feedback circuitry of the switching PSU unhappy. DLT4500 has it's PSU stashed away in an ill ventilated spot, the fact that the heatsinks are close to the output caps does not help either. Heat tends to kill electr. caps. Anyway, the topic at hand is more suitable for -hardware (or so) I guess. Wilko -- Wilko Bulte Arnhem, The Netherlands - The FreeBSD Project WWW : http://www.tcja.nl http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message