Date: Sun, 19 Dec 1999 11:43:14 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Louis A. Mamakos" <louie@TransSys.COM> Cc: Tim Tsai <tim@futuresouth.com>, Sergey Babkin <babkin@bellatlantic.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: Cool little 100BaseTX switch - they're coming down in price Message-ID: <199912191943.LAA06826@apollo.backplane.com> References: <199912190410.UAA01049@apollo.backplane.com> <385C60FC.7613CB55@bellatlantic.net> <19991218225758.A23729@futuresouth.com> <199912190556.AAA08484@whizzo.transsys.com>
next in thread | previous in thread | raw e-mail | index | archive | help
:with a *really* big heatsink attached -this is the "bridge on chip". And
:I noticed another, smaller IC which had a hole blown out of the epoxy case
:(which subsequently allowed the smoke to escape.
:
:It was than than I make the connection - Hmm.. SGI LCD monitor don't work.
:Ethernet switch makes smoke. Ethernet switch wants 5VDC power brick.
:SGI LCD monitor wants 12VDC power brick. Ooops!
:
:So, after switching power bricks, the SGI LCD monitor starts working again.
:It really wants 12V and not 5V.
:
:louie
Ouch. That switch is using a terrible design if it blows up with too
high a DC voltage input!
I really hate these switching regulated DC wall plugs. They always use
cheap caps in them to save money and then don't bother adding any
protection to the motherboard. I prefer AC wall plugs or unregulated DC
wall plugs and then a small switching regulator on the motherboard. That
way you can throw anything up to 40V into it and it will still work.
In BEST's early days we were using off the shelf USR sportsters for our
modems. Sportsters have a heat problem mainly due to bad design, but
they *did* have a switching regulator on board and after dissecting it
I determined that we could simply bump up the unregulated AC going into
them by a couple of volts (which reduces the current going through the
switching power supply and thus reduces the heat).
-Matt
Matthew Dillon
<dillon@backplane.com>
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199912191943.LAA06826>