[Coco] Coco RGB to SVGA

[lciotti at lrlc.us]

Roy put me down for one.

Sent from my iPhone

> On Jun 20, 2015, at 4:36 PM, John B <trymyz at gmail.com> wrote:
> 
> Roy,
> 
> Great news.  Put me on the list for one with an enclosure.  How long do
> they take to produce?
> 
> Thanks,
> 
> John
> 
> On Sat, Jun 20, 2015 at 4:30 PM, Roy Justus via Coco <coco at maltedmedia.com>
> wrote:
> 
>> Dear coco friends,
>> 
>> 
>>      I have nearly recovered   from illness and loss of my data files
>> so I am getting ready to restart production of my converter.
>> 
>>      I also  want to discuss some aspects of the process of conversion
>> of Coco RGB.     First is the noise some see with early version of my
>> converter.   Most common is the vertical bands seen during use.
>> Another is the distortion seen with some foreground/backround
>> when viewing 80 column text.   Typically the blue in a cls(7) backround
>> in SECB.   At first I tried to eliminate this noise  but had little
>> success doing it.
>> 
>>     The basic problem is this noise comes out of the GIME chip and
>> not from any outside source.    The reason it didn't show up in the old
>> 15 khz CRT displays is that they naturally filtered the signal due to thier
>> low bandwidth response.
>> 
>>    The second problem is that my earlier converters and other commercially
>> availible units have a hard time keeping an LCD display locked.    LCD's
>> have
>> such highbandwith the noise coming out of the GIME confuses them and they
>> shut down.
>> 
>>    If you want to use a converter that won't sync to an LCD try it on a
>> older CRT SVGA
>> display.    This applys to my old units and commercially availible ones.
>> 
>>    To  address these problems I have lowered the bandwith of my converter
>> with
>> some low pass filtering on both the data lines and sync inputs.    I have
>> also changed
>> the PLL tank circuit values to address the phase lock problems.   I have
>> tried my
>> new converter on no less than five "picky" LCD's and they stay on and
>> sharp.
>> 
>>     Another problem is the price of my converter.      It cost
>> approximately $100 per
>> unit to build but I think that is way too high.     I  am going to offer a
>> board level
>> unit for $40  and  a unit with enclosure for $60.   I don't do this to
>> make money.
>> i do it because monitors for the Coco3 are becoming very rare and I enjoy
>> it.
>> 
>>   So let's light up the summer with coco3 displays and send me your
>> order for one.    A board level unit comes with all the connections for
>> a great repak project and the unit in with enclosure looks good on the
>> shelf with the coco3.
>> 
>> 
>> 
>> Roy Justus
>> rjrtty at aol.com
>> 
>> 
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> 
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