[SI-LIST] Power/GND and fires
- From: "Shawn Arnold" <shawn@xxxxxxxxxxxxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 6 Jun 2006 15:29:06 -0700
Hi All,
I am in the process of diagosing a backplane to plug-in card fire in a
rackmount chassis which erupted after the system was left running
overnight and would appreciate any inputs.
The backplane has/had discrete power planes for +3.3V and +5V along with
multiple GND planes. The powers were delivered to the backplane from
Vicor type power bricks and solidly attached with multiple power tabs
and power bars. As this is a large backplane, the total current
available is 120A.
At the time of the "incident", the 13 slot system was lightly loaded
with only 1-2 cards but all power bricks were supplying voltage to the
backplane. There are no indications of capacitor failures and the fire
seems to have begun on the plug-in card, a single-board-computer (SBC)
immediately at/after the press-fit 2mm hard metric connectors and before
the first row of ASICs. There were no obvious pin shorts due to bent or
misaligned pins
The immediate suspicion is run-away voltage due to thermal/resistance on
the SBC and the lack of current limiting on either the power modules,
backplane, nor SBC, of course this will be addressed. We intend on
measuring the pin-pin resistance at low power and full power for clues
to satisfy customer concerns.
We will also be concentrating on the PCB design/fabrication in this same
area looking for potential shorting mechanisms.
All comments and enlightening fire stories welcome.
Regards,
Shawn
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
