trs-80 model II trouble--problem solved..and follow-up

Ethan Dicks ethan.dicks at
Wed Dec 16 15:42:59 CST 2009

On Wed, Dec 16, 2009 at 3:21 PM, Tony Duell <ard at> wrote:
>> Thanks to everyone's advice.  You were all right (as was my original
>> suspicion)...that it was the video memory.
> Well done!/ Repairing this old hardware can be fun, and it's a great
> feeling when it works again (or at least is is for me).


>> So...a couple of questions:
>> 1)    How can I get just 1 2114...
> Get more 2114s :-). In my experience it's one of the most unreliable
> chips there is, to the extend that I've replaced them in just about
> everything I've got that uses 2114s at some time or another.

I second that.  I've replaced many 2114s over the years.  One
commercial board I worked on in the past (the COMBOARD-I), had a field
of 32 chips.  Memory failures were one of the most common reasons
boards ended up back on the bench.  I learned to cleanly unsolder
parts from 4-layer boards because of them (clip the leads at the IC
body, then extract the pins one-by-one).  I got lots of practice.


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