Re: 7712 info

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Thu, 18 Jun 2020 22:00:28 +0200
Message-ID: <CAESs-_zuKDDddJ_uUagtbeHcaHa7X=KSq+3KUoqN6cdXL-n32A_at_mail.gmail.com>
On Thu, Jun 18, 2020 at 9:49 PM Gerrit Heitsch
<gerrit_at_laosinh.s.bawue.de> wrote:
>

>
> Yes, but often, if you have a dead C64 with a lot of 77xx chips on it
> it's one of those that is the problem (unless it's the PLA, but that is
> also known as '7700-xx' or '8700-xx').

I've repaired dozens of C64 :)
Once I've found a C64 that had almost all 77xx logic chips and one by
one I had to change them all to revive it.
I don't desolder parts before making sure they are really bad usually.
I've never said they're reliable, but they aren't either all failed by
now for sure.

What is really "disturbing" in the MOS reliability issue is that it
appears to  depend on the part number too.
Either some parts were made in different farms, so the less reliable
farms were producing the less reliable part numbers
or it was heat-related maybe (like the hotter parts failing more often)...
I tend to believe it was a "farm" issue.

Frank
Received on 2020-06-18 23:00:03

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