[Coco] Coco1 repair parts ?? & Results of Repair!!

[Robert Gault]

Robert Emery wrote:
><snip>
> So I changed tacks... rather than trying to make the broken one work, I'll put
> chips into the working one until it breaks. Not only the SAM chip, but all the
> ram died as well. The dead one has 8040517's and the good one has 8040665(?).
> Can these be intermixed? CoCo was dead with any one of them in the board.
> 
> At any rate, by putting the good SAM & RAM into ol'grey, I got to see her
> cursor flash again, so I know she's fixable.
> 
> Bob
> 

I don't have all the info needed to answer this. The 8040665 part # is 
listed as 32K RAM, 8040016 as 16K RAM. 8040517, I assume is a different 
sized RAM chip, perhaps 4K or 64K? I don't have a reference for that 
number and my Coco1 service manual does not mention 64K chips even 
though my F board has jumpers labeled 16/64K.

In any case, the SAM and RAM are interchangeable with each other but not 
necessarily with the Coco. The F board manual says, " The new p,c, 
boards accept 16K or 32K RAMs only. They do not accept the old 4K RAMs." 
Also you must correctly select the RAM jumper settings and with 32K RAM 
remove bypass caps on each IC.

My guess is that you may be trying 4K RAMs on an F type board.
You're sure both boards are type F? You're sure the "bad" board did work 
for you at some time? Are the jumper settings the same on both boards?