Re the Simon's comment now that I am at a real
keyboard and not a mobile phone I'll expand on my experiences.
I did socket those 4164s when I replaced them on
the memory board. However it wasn't plain sailing for the very
reason Simon mentions.
To replace the chips I clipped off the faulty IC's
then extracted the pins by heating the solder pads from underneath and pulling
the pins through. I then cleaned up residual solder from each hole with
solder wick before fitting a socket. In one of the boards this went
smoothly with no problems. On the second board however, I managed to
damage two of the holes (or connections to them) when trying to clear out old
solder. Once i finally cleared it I could see a bit of board damage under
magnification and in one hole I could see I'd damaged a connecting track.
I used thin connecting wire on the bottom of the board to bridge this break
and to take the signal to where it should go.
Firing the board up I found it was still
faulty!? A check of numbers showed it was the same column/row
location. I knew it wasn't the chip so I figured I must have damaged
something else. Eventually I found a connection to the adjacent RAM chip
that wasn't being made, even though I couldn't see any obvious damaged tracks
from the hole in question. Anyway, I wired in a bridging wire and the
board now works as good as gold.
Anyway, as Simon says, resoldering these
boards is not as easy as some. Certainly this is the first time I've
had problems like this and I've done quite a few chip replacements now...mostly
on single layer boards though..
Terry
----- Original Message -----
Sent: Sunday, March 27, 2011 11:26
PM
Subject: Re: Troubleshooting X/Lisa RAM
boards - first draft
Thanks. I replaced the chips before i read your email. As it was i
did use sockets anyway so that was a lucky thing. Both boards work fine
now. Great!
On 27/03/2011 10:08 PM, "simon" <simski@dds.nl> wrote:
use a socket
for the chip. resoldering double layer boards wrecks them a bit. even with a
reflow station.
On 26 mrt 2011, at 23:15, Terry Stewart
wrote:
> James,
>
>> Bit 0 maps to column 22 on
the memory...
--
Groeten,
Simon
simski@dds.nl
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