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From: s37837k@saha.hut.fi (Jari Lehto)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: GCR / MegaST problem?
Message-ID: <1991Mar21.114110.8813@santra.uucp>
Date: 21 Mar 91 11:41:10 GMT
References: <28122@dime.cs.umass.edu>
Sender: news@santra.uucp (Cnews - USENET news system)
Reply-To: s37837k@saha.hut.fi (Jari Lehto)
Organization: Helsinki University of Technology, FINLAND
Lines: 38

In article <28122@dime.cs.umass.edu> SNYDERS@process.com (John Snyders) writes:
>I just purchased a used spectre GCR. When I started using it in mac mode it
>would crash. I looked in the documentation and it says that some Mega2s had
>some marginal chips in them and the solution was to replace them.
>
>I checked my machine and sure enough I have the bad chips (SGS 74LS373).
>
>I am thinking of doing the work myself and would like to hear from anyone
>who has had this problem and can offer any advice such as.
>
>- Replacement chips used. I would hate to put in new chips that have the same
>problem.

Non-SGS 74LS... OR: For improved handling 74HCT373 or even better 74ACT373.
They are 100% compatible, but much more faster and reliable. They are
essential if you are planning to install an accelerator later...

I changed my 1040 to Mega4 and first thing was: 74LS's out and 74ACT back...

>- Tips on soldering. My main concern is heat damage to other chips and the new
>chips. I have done soldering before but not on a pc board.

Small enough tip and keep it well cleaned! Not too hot. Loose the old chips
one pin at a time, warm the pin and pull it up with a small screwdriver.
If you have IC desoldering tip, use that. Vacuum tin-removers are not reliable
for taking ICs off from a pc board... The holes are so small.

>- How difficult is the job. Is there any thing else I should know.

Not very, but takes a little time... Don't burn your fingers!

>Thanks,
>
>John Snyders                                email: snyders@process.com

			Jartsu

	*** Jari Lehto, jartsu@otax.hut.fi, s37837k@saha.hut.fi ***