On Mar 2, 2006, at 4:51 PM, Kevin Worth wrote:
> We RMA'ed our netCF board once because it was not working reliably.
> Gumstix techs tested it, said it worked fine and sent it back. It did
> work when we initially had it back, however, it has gone back to
> working intermittently. The module appears to load correctly most of
> the time (although sometimes it gives some crazy watchdog errors).
> However, it reports that there is no cable plugged in.
It sounds unlikely to be the jack, but more likely actually it sounds
like it'd be the controller chip itself which is having trouble. If
it were just the RJ45 jack, then you'd fail to communicate with the
network, but the gumstix CPU would have no problem loading the driver
and talking to the ethernet controller -- both would be merrily
unaware of any problems down the wire -- they'd just assume there was
no cable plugged in or something, rather than locking up. We
probably checked the board visually if you sent it to us, so it's
probably not anything visible in the solder on the controller chip or
elsewhere on the important parts of the board; it could just be a bad
chip. If the problems which you originally reported have in fact
returned for you, then we'll just go ahead and send you a new board
(no need to return that one to us yet again). I've entered the
request into our system, so you should receive the new board in a day
> I did some testing with a multimeter and found that the pins on the
> RJ45 socket don't seem to connect to the solder points on the board.
> Is this correct or do we have a bad RJ45 unit? The solders look fine
> and I can't get conductivity through ANY of them, so I'm wondering if
> something inside the jack is... jacked up. Should these wires be
> straight through?
I'm not understanding clearly where you're failing to measure
conductivity. Do you mean between the pin inside the RJ45 where the
cable would contact, through to where the pin is soldered into the
board? Those are not just wired through directly -- there is
magnetic voodoo going on inside the RJ45 jack module thingie. See
"Circuit D" on page 2 in this:
You'll notice air between everything on the right and everything on
the left. Oscillating signals will come through, but not constant-