RE: A85: Expander SF

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RE: A85: Expander SF



-----Original Message-----
From:	Mel Tsai [SMTP:tsaimelv@pilot.msu.edu]
Sent:	Saturday, August 30, 1997 10:02 PM
To:	assembly-85@lists.ticalc.org
Subject:	Re: A85: Expander SF

>[Jan Zumwalt]  I just went through the same experience and found out that
>the problems is the 2.5mm jack used by TI MUST have a smooth barrel. The
>common ones available at Radio Shack have a detent that helps hold the jack
>in but WILL NOT MAKE CONTACT in the TI female socket. The TI female just uses
>raised bumps in the barrel for contacts while the walkman style has metal 
>fingers that project down.
>
>I ended up cutting my TI link cord in half and splicing onto it. I am now
>going to look in Newark or Allied for the proper jack. If I find the, I will
>order two dozen or so for other people.
>
>--------\/\
>   |   |   >  Walkman style jack     /---  Walkman contact
>--------/\/                       \_/
>
>-----------                        _  _   TI contact
>   |   |   >  TI style jack         \/
>-----------


This is a rumour that needs to be put to rest :).  The "walkman style"
plug *will* make contact!  I've sold about 45 expanders which work and
they all have that style plug.

The problem occurs at the linkport itself.  After heavy use, the
linkport jack starts to wear out, and the walkman-style plugs are the
first ones to notice connection problems, whereas the TI plugs still
work fine.  

[Jan Zumwalt]  I have owned my TI-85 for less than a week and the
new jacks did not work. I opened the calc and took a VOM meter to
discover the problem. I would guess that I have put a jack in it less 
than 20 times.

However, the TI style plugs will soon follow!  Opening
your 85/92/whatever will quickly reveal that TI made a piece-O-shit
linkport that fails very quickly after moderate to heavy use.  This is
the main reason why many expanders I sold didn't work, because
people's linkports were worn out.  They would take their expander to a
friend's calculator and it would "mysteriously" work, but really it
was because their friend had a less-used linkport.

[Jan Zumwalt]  TI used a surface mount female connector so it would be
pretty easy to replace if a miniature one could be found.

 Basically the linkport is the #1 issue when it comes to expanders.
Often times the only solution is complete linkport replacement.

-Mel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The TI-Memory Expansion Homepage
-http://www.egr.msu.edu/~tsaimelv/expander.htm
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