On May 10, 2004, at 12:45 AM, Sean Davis wrote:
>>    I do this sort of work all the time.  Is this a surface mount chip,
>> or a through-hole?
>
> I'm not entirely certain. All I know (since I haven't taken the
> motherboard out) is that it's mounted flush to the motherboard. I am
> assuming by "through-hole" you mean it's stuck through holes on the
> board and soldered on the back? If so, I'm pretty sure that's the
> case: I don't see any solder near it on the board.

   Umm ok..."Through-hole" means there are holes drilled in the board, 
and the chip's pins stick down through those holes and are soldered.  
Usually you can see some solder on both sides of the board, around the 
pins.  A surface-mount chip is just that...its pins generally come out 
of the sides of the chip and fan out horizontally, and are soldered to 
pads on the board with no holes.

   Most of DalSemi's chips are available in through-hole and at least 
one or two different varieties of surface mount packages.  Your first 
step will be ascertaining if the ones you got from DalSemi are in the 
same package as the one on your board, and then seeing if the pinouts 
of the two chips are compatible.

   Argh.  Ok, I overcame laziness for a brief moment and downloaded the 
datasheets.  The DS12887 is only available in a through-hole package.  
Most people will say this makes it easier to deal with, but I work with 
both all the time and I think surface mount is FAR easier.  But no 
matter.  Assuming you don't want to save the chip you're replacing 
(it's dead, right?  otherwise why replace it?), the right thing to do 
is to use flush cutters to snip the old chip's pins as close to the 
chip body as possible, and remove the chip.  Then, using a hot, 
preferably temp-controlled iron, remove each pin from the top of the 
board with tweezers.

   Then carefully solder a socket (ALWAYS replace a through-hole chip 
with a socket) in its place, and plug the new chip in.

   If you're uncomfortable with the idea of doing this, you can send the 
board and chips to me, along with a picture of a beer (I don't think 
it's legal to ship actual beer, is it?) and I'll swap 'em out for you 
and send 'em back.

            -Dave

--
Dave McGuire          "PC users only know two 'solutions'...
Cape Coral, FL          reboot and upgrade."    -Jonathan Patschke