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

Mon Jul 20 00:37:23 EDT 2015

Steve,

The video quality is very good.  If I have to adjust the POT depending on
what I am running, I am perfectly fine with that.  Luis did a great job and
I am very thankful for all the work that everyone has put into this
project.  I am sure there will be improvements along the way.  With  Roger
and Ed we are in good hands. :)

On Mon, Jul 20, 2015 at 12:06 AM, Steve Batson via Coco <
coco at maltedmedia.com> wrote:

> I think I've pretty much confirmed number 2 below, I swapped out my VGA
> cable and things got better...I can still see improvement or degradation
> moving the ribbon cable around. I'm going to attack that as I have time and
> find the appropriate parts to build a better, shorter, possibly shielded
> ribbon cable. I will be interesting to see what you come up with.
>
>
>
> On Jul 19, 2015, at 9:03 PM, Steve Batson via Coco <coco at maltedmedia.com>
> wrote:
>
> > John,
> >
> > I agree with Ed. It is darn good. Keep in mind that Roger's resistor
> values were found through a lot of work on his part. He did mention that
> some changes to the code could probably clean it up more, but the code used
> to build the .JIC file doesn't seem to be available. When he tried to
> compile what is available, he had issues. That's when he was told to use
> the included .JIC file. Like Ed, I do have mine pretty darned stable but
> it's not perfect. When I adjust the POT, I can get it to look really good
> on most stuff, but haven't found a sweet spot for everything.
> >
> > From everything I've seen so far and from what Roger found, I think
> there are two main things going on.
> >
> > 1) There is some noise needs to be dealt with in the FPGA Code, possibly
> in combination with further tweaking with the board components. And while
> I'm not a Video Expert or electrical engineer, I find it extremely
> interesting that there are no RF filtering circuits on the RGB2VGA board. I
> would think that any noise that makes it way to the card could ride the
> signals right out to the VGA port. Possibly there are still some signal
> level issues that are creating some noise or allowing to the vga port.
> >
> > 2) I'm almost certain that some of the noise I'm seeing, and sounds like
> you too, is RF Interference. The waves or rolling effect. And I think you
> are on the right track of looking to a shorter ribbon cable as it may be
> picking it up from outside from computer or monitor powers supplies. The
> reason I say this is that when I move the cable around and reposition it,
> it sometimes gets better and sometimes worse. I'm thinking a shorter cable,
> or maybe a shielded cable will help. You must have come to this conclusion
> about the same time I did. :)
> >
> > Anyway, as several of us have mentioned, it's still an outstanding
> product and much better than most of us had before. And not having a
> working RGB Monitor, it's awesome to be able to use with LCD monitors of
> today.
> >
> > In any case, if enough of us keep at it, we should be able to get this
> thing darn near perfect. I think Roger has a a pretty solid understanding
> of it now as is evident from his work. Now with Ed involved, there are two
> very talented people looking at it. I will help anyway I can, test, etc.
> but currently Roger and Ed have much more knowledge than I do about the
> CoCo and hardware interfacing to it.
> >
> > I'll be building a second board soon to use as a spare, maybe it will be
> cleaner...we'll see. If even newer resistor or other changes come up, I
> could test those.
> >
> >
> > Steve
> >
> > On Jul 19, 2015, at 7:23 PM, John B <trymyz at gmail.com> wrote:
> >
> >> 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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