On Wed, 17 Apr 2002, Sellam Ismail wrote:
> On Wed, 17 Apr 2002, Tothwolf wrote:
>
> > > http://www.vintage.org/special/apple-1/apple-1-rear.jpg
> > > (this one has had a couple sockets replaced)
> >
> > Well, I can spot at least one replaced dip socket, bottom right corner of
> > that image, second chip from the right edge. Which others did you notice?
>
> That is one of the monitor ROM sockets, which was defective and was
> replaced when the seller first got it (if you haven't read the
> background info, it was donated in non-working condition to the
> Homebrew Computer Club to raise funds, and he paid something like $80
> for it, which was a real good deal even back then). He also replaced
> the keyboard socket with an Augut socket that was much more robust
> (second row from the bottom, fourth socket over).
That explains why the joints on monitor ROM socket are uneven and not
defluxed. (If you decide to deflux it, be careful what type of cleaner you
use -- some melt certain plastics.) The Augut socket was indeed a good
idea if the keyboard was unplugged regularly. Those copper alloy leaf
sockets won't hold up very well to that kind of (ab)use.
> > I actually would have expected any repairs on a "rare" Apple I to have
> > been much cleaner than what I see from that image, but it's possible they
> > were made by the last owner before he figured out it was "rare". It also
>
> These were made contemporaneously, i.e. in 1976 when it was just
> another computer that needed hacking.
That makes sense. I didn't think about when the repairs were made till
after I sent my last email.
> > seems quite possible to me that one person (especially considering what I
> > read of the board's history) with very good soldering skills and the
> > proper tools did the initial build of the board, and someone else made a
> > few repairs later on.
>
> It was wave soldered. The repairs were made by the seller way back in
> 1976.
I think you are right, I didn't notice the uneven solder on the power
planes near the voltage regulator right away.
> One of the problems with making an Apple-1 replication is that the
> video shift registers are next to impossible to find. One part of the
> lot of the Apple-1 auctioned in 2000 was a set of spare shift
> registers. Those are the only I've ever seen not in an Apple-1 board.
What kind of chip do they use? Is it a custom Apple designed chip, or
something that has just been abandoned by the original chip manufacturers?
If it is the later, there are a couple companies out there now who could
reproduce the chip (in 500-1000 unit batches). I don't think the cost to
make an Apple I reproduction would be all that bad, especially compared to
what an original Apple I system typically sells for ;)
-Toth
Received on Thu Apr 18 2002 - 21:37:22 BST
