[Coco] CoCo2 black and gray video only -- need help!

[Keith Monahan]

Yeah, will do Dave. What doesn't fill me with joy, however, is that even 
a brand new in-spec crystal is potentially already too slow. If it still 
meets spec.

I'm sorry if I'm fixating here, but the Jamco/Arndt Electronics 
XTAL-14.31818MHZ-HC49U I ordered is a 50ppm crystal. That puts the 
minimum, but still in-crystal-spec value at 14.31818 * .999950 = 
14.31746. This is below the needed 14.31814 that is needed for the VDG.

Digi-key offers better parts -- a 30ppm crystal, which improves things, 
but the math still doesn't work out.

Maybe that's precisely why they include that trimcap in the design.

Keith


On 10/23/2021 11:51 AM, Dave Philipsen wrote:
> Let us know if the new crystal fixes the problem. I'm curious to know 
> the outcome.
> 
> 
> Dave
> 
> 
> On 10/23/2021 10:43 AM, Keith Monahan via Coco wrote:
>> Removed TC1 completely. No effect. I think the crystal is too far out.
>>
>> Thanks
>>
> 
>