[Coco] RE: 512 Upgrade

[Bob Devries]

The coco3 service manual is on the maltedmedia ftp site.

--
Regards, Bob Devries, Dalby, Queensland, Australia

Isaiah 50:4 The sovereign Lord has given me
the capacity to be his spokesman,
so that I know how to help the weary.

website: http://www.home.gil.com.au/~bdevasl
my blog: http://bdevries.invigorated.org/

----- Original Message ----- 
From: "Andrew" <keeper63 at cox.net>
To: <coco at maltedmedia.com>
Sent: Wednesday, August 09, 2006 11:42 AM
Subject: [Coco] RE: 512 Upgrade


> Longshot, but check for cold solder joints on the board itself. Also, 
> try putting the 128K back in, jumper the caps you removed back in place, 
> and make sure the machine still works as a 128K machine. If so, then it 
> has to be the board, but if not - your CoCo may have problems of its own.
> 
> Check CoCo3.com and/or Google for the CoCo 3 service manual - it might 
> help out.
> 
> Also, check for lifted traces, corrosion on solder joints, possible 
> broken connections on the chips themselves and any other hinkyness with 
> the board. Boards that old can get flakey. Plus, from what I remember, 
> the RS upgrade wasn't the best to begin with.
> 
> You might also try (though I have no clue if this is possible or if it 
> can be done with the board?) to pull out 1/2 to 3/4 the memory from the 
> board - what I am thinking is that one or more (but only maybe a couple) 
> of the RAM chips are bad, and maybe you could get it to run (though 
> maybe not perfectly, but enough to boot) as a 256 or 384K "upgrade". If 
> so, then maybe swap in one chip at a time in the banks and see when it 
> crashes/hangs. If this is even possible, of course (maybe someone here 
> can tell us more if this is possible?)...
> 
> -- Andrew L. Ayers
>    Glendale (Phoenix), Arizona
> 
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