[Coco] Cross Post from the Facebook Page about the RGB2VGA Board

Sun Jul 19 22:23:09 EDT 2015

I agree, definitely very good quality.  The screen is acceptable.  Maybe I
am too picky about these things and expect it to be perfect.  I have a few
things to try.  One being another monitor and the other being a shorter
cable from the CC3 to the board.  This one is almost 2 feet.

On Sun, Jul 19, 2015 at 10:15 PM, Zippster <zippster278 at gmail.com> wrote:

> If you’re running without the ground fix (much more stable), and Roger’s
> resistor
> values, I think that is about as good as it gets with this particular PCB
> without
> improvements to the FPGA code.
>
> Although I seem to be able to dial in an acceptable screen for any mode no
> problem,
> but finding one that’s perfect across all of them…. well, I guess it is
> what it is.
>
> Still darn good though.  :)
>
> - Ed
>
>
>
> > On Jul 19, 2015, at 9:02 PM, John B <trymyz at gmail.com> wrote:
> >
> > I did both.  The ground fix makes the text more unstable.
> >
> > On Sun, Jul 19, 2015 at 10:00 PM, Zippster <zippster278 at gmail.com>
> wrote:
> >
> >> Hi John,
> >>
> >> Are you running with or without the ground fix on the hsync input?
> >>
> >> - Ed
> >>
> >>
> >>> On Jul 19, 2015, at 8:41 PM, John B <trymyz at gmail.com> wrote:
> >>>
> >>> Steve,
> >>>
> >>> I built a second board this weekend with the new resistor values.  Your
> >>> sheet was quite handy.  Thank you again.  The text has definitely
> >>> stabilized but a few other things are off.  The left edge of the screen
> >> is
> >>> kind of wavy and gray lines are wavy.  For example in KQ3, everything
> >> else
> >>> is stable, except the gray lines (lines in the stairs and wall).  They
> >> seem
> >>> to shimmer.  I have adjusted the potentiometer but going to far either
> >> way
> >>> causes other issues with the image.  I know you recommeneded a
> multi-turn
> >>> potentiometer.  Which one are you using?  Anyway, I will most likely
> try
> >> a
> >>> higher quality monitor and see if the image improves.  Currently I am
> >> using
> >>> a cheap Dell 17 inch that was in the attic.  Maybe I am being too picky
> >> and
> >>> this is as good as it gets.
> >>>
> >>> John
> >>>
> >>> On Sun, Jul 12, 2015 at 4:53 PM, John B <trymyz at gmail.com> wrote:
> >>>
> >>>> I am pretty sure it will stabilize with new resistor values.  Compared
> >> to
> >>>> composite, it looks pretty darn good now.  OSH Park only sold the
> >> boards in
> >>>> lots of 3 so I have 2 spares.  I will definitely complete the other
> one
> >>>> with the new values.  Haven't decided if I will build the third one
> yet.
> >>>>
> >>>> On Sun, Jul 12, 2015 at 1:04 AM, Steve Batson via Coco <
> >>>> coco at maltedmedia.com> wrote:
> >>>>
> >>>>> John,
> >>>>>
> >>>>> Trust me, unless you have something else wrong with the board,
> Roger's
> >>>>> recommended resistor changes will clean things right up. Mine looks
> >> awesome
> >>>>> and I simply duplicated his changes. Since I had a few resistor
> >> changes, I
> >>>>> may end up buying another board and building one up fresh with the
> >> right
> >>>>> resistors the first time. The board will certainly look better and it
> >> won't
> >>>>> hurt to have a spare. I'm not going to buy a spare FPGA
> >>>>> though...hehehehe...that's a bit pricey.
> >>>>>
> >>>>> On Jul 11, 2015, at 9:48 PM, John B <trymyz at gmail.com> wrote:
> >>>>>
> >>>>>> Definitely great news.  Hopefully the new resistors will take care
> of
> >> my
> >>>>>> jitter/wavy lines and text problem.  I will find out next week.
> >>>>>>
> >>>>>> On Sun, Jul 12, 2015 at 12:42 AM, Steve Batson via Coco <
> >>>>>> coco at maltedmedia.com> wrote:
> >>>>>>
> >>>>>>> I changed the last 4 resistors and didn't really notice much
> >>>>> difference,
> >>>>>>> but since values were based on Roger's research and testing and
> that
> >>>>> his
> >>>>>>> board is now solid, I figured I'd do the same. I've Tested all of
> the
> >>>>>>> features and it's incredible results.
> >>>>>>>
> >>>>>>> The output is rock solid. Colors are Rich. Text looks fantastic in
> >> 32,
> >>>>> 40
> >>>>>>> and 80 columns. I've tested Zaxxon, Grabber, Tetra3, Brewmaster,
> >> Donkey
> >>>>>>> King. And The biggie, Sockmaster's port of the Original Donkey Kong
> >>>>> and it
> >>>>>>> Looks Awesome! Very happy with the results of this thing. It was a
> >> lot
> >>>>> of
> >>>>>>> work, but it was well worth it.
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On Jul 9, 2015, at 8:45 PM, Steve Batson <
> >> steve at batsonphotography.com>
> >>>>>>> wrote:
> >>>>>>>
> >>>>>>>> I figured I'd post the following here too. Some discussion
> occurred
> >> on
> >>>>>>> the FB page, but a lot of discussion was done between Roger and
> >> Myself
> >>>>> in
> >>>>>>> email as Roger made several discoveries that stabilized some very
> >>>>> annoying
> >>>>>>> jitter problems with video.
> >>>>>>>>
> >>>>>>>> RGB2VGA Stabilized!
> >>>>>>>> First thanks to Felipe for a very cool Solution to bring the CoCo3
> >>>>> video
> >>>>>>> to Modern VGA Monitors. Originally, I missed a few resistors that I
> >>>>> somehow
> >>>>>>> thought were optional and Felipe straightened me out on those.
> >>>>>>>> Then I was getting Jitter just like Roger was experiencing. I had
> >>>>>>> several email discussions with Roger as he was doing some research
> >> and
> >>>>>>> experimenting based on what he found about the VGA standards and
> >> found
> >>>>> that
> >>>>>>> changing some resistor values stabilized the output from his
> board. I
> >>>>> have
> >>>>>>> pretty much duplicated Roger's resistor values on my board with the
> >>>>>>> exception of 4 that I'm waiting to come in, but mine is crisp and
> >>>>> jitter is
> >>>>>>> gone. I will most likely change those 4 resistors when the parts
> come
> >>>>> in
> >>>>>>> unless it doesn't make sense.
> >>>>>>>> Anyway, Finally fantastic output on my VGA monitor. Very Cool!!!
> >>>>>>>> Very Big thanks to Roger!!!
> >>>>>>>>
> >>>>>>>> --
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> >>>>>>>
> >>>>>>>
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> >>>>
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