Re: Burnt ATX Connectors on ASUS Motherboard

"Paul" <nospam@xxxxxxxxxx> wrote in message news:eunhf4$paq$1@xxxxxxxxxxx
Eric Wolfe wrote:
"Paul" <nospam@xxxxxxxxxx> wrote in message
deKever wrote:
Does any one have any clue as to where I might get an ATX power
connector set, to replace the ones on the mobo and the cable. I
both ASUS and Antec, the power supply manufacturer, but all they tell
is to request an RMA number. The mobo and PS are out of warranty, so
they are no help. I removed the 5 volt pins on the mobo, they are
totally coroded. I contacted Molex The manufacturer of the Connector,
but they don't bother responding.

ATX spec:

Motherboard - Molex 39-29-9202
PSU shell - Molex 39-01-2200
PSU pins - Molex 39-00-0039

Sample catalog pages and Engineering drawings: actually has all the parts.

Motherboard end - $2.57 for one 20 pin solder connector. Tin plated.

PSU Nylon shell - $1.12 for a 20 pin shell.

20 crimp pins for PSU Nylon shell - $1.80 total*39000039*&Ms
So Mouser wins a prize. Digikey didn't stock the Mobo end.


Very thorough answer! Any speculation as to why such corrosion would
I've never seen it happen before, but I'm sure I'd never like it to
to me!


Well, the OP says "Burnt" in the Subject line, so my guess is
too much current was drawn on the +5V rail. I believe the pins
are rated for 6 amps each, on the main power connector.

While it doesn't happen too often, sometimes the motherboard
designer makes a mistake when working out how much current can
be safely carried. This board powers two AthlonMP processors
from the +5V rail, and that can cause the 6 amp per pin rating
to be exceeded. Leading to some people experiencing burnt
pins, as shown in the pictures below.

Motherboard damage:

PSU connector damage:
Yes. This was a very common problem with the Tyan Tiger (S2460)
motherboards, and quite a few similar ones using processor pairs like this
(and quite a few of the early single P4 boards as well). This was why the
extra 12v connector was added to the ATX power supply specifications. The
processors don't have to be powered from the 5v rail for problems. When
you look at the average consumption, of a pair of these processors, add
some power for other things, and even the 12v rail has problems delivering
this much...
The systems don't have to exceed the specs at all. The 'specs', are a
little generous on their rating for the connector pins, and some
manufacturers use different metals for the pins and sockets. When systems
are left with the plugs reasonably heavily loaded, accelerated dissimilar
metal corrosion can start at the surface, which then heats the pins
further, and things get worse. :-(
It used to be standard advice on some machines with boards that had this
problem, to remove the plugs once a year, and give them a wipe of contact
oil, then re-insert them.

Best Wishes