[Coco] Help! A CoCo2 died on me!

[Gene Heskett]

Fedor Steeman wrote:
> Hello all,
> 
> I have now uploaded some pictures of the inside of the CoCo2 to show the
> video mod. More technical details and pictures will follow later:
> 
> http://www.coco3.com/gallery/v/User+Albums/CoCougar/BrokenCoCo2/
> 
> Any help is greatly appreciated!
> 
> Cheers,
> 
> Fedor
> 
The only thought that comes to my mind is that a portion of that board 
projects under the heat sink for the pass transistor, possibly touching, 
and wearing thin the black anodic coating on the heat sink.  This 
normally has a 50-400 volt dielectric withstand, but if something on the 
video board is touching that heat sink, it might short to it.  Its not 
clear how that extra board is mounted and if its not pretty solid it 
could short something on the board to the heat sink.  ISTR the full 8+ 
volt output of the rectifier is on the heat sink.  I blew both pics up 
to full resolution but nothing else jumps out at me.  I've never seen a 
memory board like that one either, except in a project kit the shack 
used to sell 20? years ago.

Whoever did this, I must say it looks pretty well done.

-- 
Cheers, Gene