Re: Question on Corvus controller card repair

[Charlie Springer <RAM@regnirps.com>]

On Fri, 26 Aug 2005 13:02:30 -0700, Bill Garber wrote
(in article <F86dndw7WebI6JLeRVn-pg@comcast.com>):

> "Kellion" <citaria@hotmail.com> wrote in message 
> 1125083654.765539.165620@g44g2000cwa.googlegroups.com">news:1125083654.765539.165620@g44g2000cwa.googlegroups.com...
>> 
>> 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.
> 
> Put sockets in while you have the chips out.
> 
>> 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.
> 
> The stuff before the number is the MFG signature.
> I'd have to look up the "N" part, but I believe you
> are correct.
> 
>> 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.
> 
> Jameco, Jameco, Jameco, need I say more. I buy most of my
> prototype parts there. Cheap and I can buy 1, 10, 100, 1000,
> if I so choose to.  :o)

Good choice. I used to drive to the storefront part of the business in 
Redwood City (by the giant salt piles). If they don't have it, Digikey.com. I 
used to buy production runs from Digikey and they sell singles. In fact, they 
slaughtered the traditional jobbers by offering large quantity pricing for 
low quantities for the hobbyist (or product developer of course) with super 
quick delivery and easy phone ordering from their now rather huge catalog. 
Fry's did the same thing in Sunnyvale with a retail outlet selling for lower 
cost than the big wholesalers. You could run into ANYBODY picking out parts 
at Fry's.

If you have access to a vacuum desoldering station or are good with a spring 
solder sucker, I agree. Take them all out and put in sockets.

Just Google a generic part like SN7400 and you will get Texas Instruments 
Plastic. HD7400 gives Hitachi. But what really matters is the in between 
part. though there are various compatible families, because of possible 
timing differences it would be best to get the right family member. For 
example, a 74LS244 is not the same as a 74HC244 as far as output levels and 
drive. For 74XX244, look for and XX version. If you can't find it, ask here 
and one of us probably can give compatibility advice.

-- Charlie Springer