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From: beatyr@pur-ee.UUCP (Robert Beaty)
Newsgroups: net.micro.atari16
Subject: 1Meg Upgrade Warning
Message-ID: <3806@pur-ee.UUCP>
Date: Mon, 24-Feb-86 23:28:07 EST
Article-I.D.: pur-ee.3806
Posted: Mon Feb 24 23:28:07 1986
Date-Received: Fri, 28-Feb-86 01:08:15 EST
Reply-To: beatyr@pur-ee.UUCP (Robert Beaty)
Organization: Electrical Engineering Department , Purdue University
Lines: 25

<<>>

  This is just a subtle warning to all of those interested in upgrading
their Atari 520ST's to 1Meg. I attempted to do so two weekends ago and
the result was a non-functional 520ST and about 24 hrs. of wasted time.
  Now there will be those out there that will say that I might have
used a wood burning gun instead of a nice soldering iron, but that is not
the case. I am getting my Ph.D in EE and have worked as a tech. for many
a summer. I have performed similiar upgrades to H-19's and Radio Shack
Color Computers ( piggy-backing chips and the like ). This upgrade is
NOT a simple one. It is not due to the fact that the techniques are that
difficult, just that the component values are VERY touchy.
  For instance, I tried BOTH the resistor and non-resistor upgrades -
neither worked. I have seen ( since I tried my upgrade ) about the fact
that the values of the resistors are sensitive to the manufacturer of
the 256K DRAM chip. This is not my idea of a good, safe upgrade.
  My only warning is this, DO NOT try this if your 520ST is AT ALL as
valuable to you as mine is to me ( doing without it for 2 wks. was very
tough ). If you have the time and the persistance to MAKE it work then
you might want to try it. If possible, find out EXACTLY what combination
of components worked for someone else ( any offers out there? ).
  I am not trying to bad-mouth anyone, only trying to save someone like
myself a LOT of grief.

                   Bob