Re: Question on Corvus controller card repair

[et472@FreeNet.Carleton.CA (Michael Black)]

"Kellion" (citaria@hotmail.com) writes:
> Unfortunately the chips are not in sockets so it means I have to pull
> them off the board.  Not a big deal unless you have clumbsy fingers
> like myself. heh,  Chips are cheap so I think I will locate the chips
> and perform some surgery.
> 
Since they are common parts, you might do well to cut the pins on
the ICs (making sure you've marked what goes where), and then desolder
the pins one by one.  To get the ICs off in one gulp, you need heat
and likely leverage, and that does always run the risk of damaging the
board.  If you take them out pin by pin, you only heat one pin at a time,
and it's real easy to pull the pin just as soon as it gets hot enough.

This doesn't work if you want to keep the ICs, but that's not the case
here.  And much of the time when you want ICs off a board, the board
doesn't matter.

> Question: 2 of the chips have a "SN" at the beginning and 2 have a "HD"
> at the beginning.  Do you know what those numbers stand for.  I believe
> the "N" at the end represents it being a "plastic" chip as oppose to
> ceramic.
> 
It's  a manufacturer's prefix.  These are common and standard parts,
so it doesn't matter what manufacturer you get them from.  The key
part is the 74LS20 part (I seem to recall that was on the list) and
who makes it is irrelevant.  You do want the LS part, which denotes
the subfamil (low power schottky), because if that doesn't match 
there may be interface problems with the other ICs.

   Michael

> Any recommendations on a good website where I could easily find the
> chips I need?  Went searching around and kept finding sites that wanted
> me to order 100 at a time.
> 
> Thanks,
> Kellion...
>