[Coco] Re: [Color Computer] Video garbage on CoCo

[Phill Harvey-Smith]

brunkfordbraun wrote:
> My CoCo is outputting random video junk, does not respond to
> keypresses, and does not go to the command prompt. There are many
> different things the video has done, but here are two samples:
> 
> http://img56.imageshack.us/img56/4391/junk17wt.jpg
> http://img56.imageshack.us/img56/3977/junk29os.jpg
> 
> Is this a common problem? Is this something I could fix with my own
> soldering skills, is there someone out there who still fixes these
> things, or am I just better off tossing it? 

You don't say what sort of CoCo it is (1,2,3), but to me it looks a 
little like a RAM fault. If it where a CoCo 1 or 2 could also be the 
SAM, or possibly the video data latch.

If it is a RAM fault, you may be able to identify the faulty chip(s), by 
leaving the machine on for a short time, and checking to see which chips 
are getting hot, the 6809, SAM and VDG normally get reasonable warm anyway.

Also, if you are going to try and diagnose the problem, excersise 
caution as the CoCo has potentially leathal mains voltages inside the case.

As to wether it's fixable that depends on your soldering skills :)

HTH

Phill.



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