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

[John B]

Thank you very much Steve.  I should be able to test it out today.  I will
report back either way.  I might put my DigiKey order in anyway.  You can
never have too many resistors :)

On Fri, Jul 10, 2015 at 9:07 AM, Steve Batson <steve at batsonphotography.com>
wrote:

> John,
>
> No, the resistor from R7 to Pos 8 on the GPIO1 connector is what was
> referred to as Rx, that resistor should be 1.8K. The drawing on Luis' site
> shows a jumper wire to fix a ground issue. If that jumper is in place after
> all the resistors in place, you will most likely have Jitter. There should
> be no Jumper wires installed. The jumper Luis refers to is between R21 and
> R18. I'd only install that if Jitter is present with all the resistor
> changes. If necessary, try it both ways, but on Roger and my board it
> wasn't necessary. All of these changes were Roger's findings. I only
> duplicated his setup and it's awesome!
>
>
>
> On Jul 9, 2015, at 10:22 PM, John B <trymyz at gmail.com> wrote:
>
> > I will be testing it tomorrow.  Thank you for the new values.  Hopefully
> > everything will work as intended.  You refer to the additional wires not
> > being needed.  Is this the resistor from R7 to Position 8 on GPIO1 and
> the
> > wire between R18 and R21?
> >
> > On Fri, Jul 10, 2015 at 12:56 AM, Steve Batson <
> steve at batsonphotography.com>
> > wrote:
> >
> >> John,
> >>
> >> Yes, this is Luis' RGB2VGA board used with the DENano FPGA.
> >>
> >> Since you have just finished it, I'd test it out first to see if you see
> >> any jitter or other problems. However Roger did a lot of investigation
> and
> >> found these values produce voltages in line with the VGA Standard and to
> >> help the board properly sync from the CoCo output. I don't have all the
> >> technical details, I just know it worked for Roger and works for me.
> >>
> >> These are what Roger came up with and I simply duplicated what he found.
> >> Also, the Variable resistor, he recommended a 10K Multi Turn for finer
> >> control when tuning for the best appearance. Another thing to know is
> that
> >> there are some additional wires recommended but they were not needed on
> >> Roger's or my case and jitter did not go away until removed.
> >>
> >> Top Left
> >>
> >> 82 Ohms - Grey-Red-Black-Gold-Brown
> >> R22
> >> R23
> >> R25
> >>
> >> * * * Bottom Left
> >>
> >> 1.2K Brown-Red-Black-Brown-Brown
> >> R18
> >> R19
> >> R20
> >> R21
> >>
> >> * * * Top Right 10
> >>
> >> R9  47
> >> R10 47
> >>
> >> 390 ohms
> >> R1
> >> R4
> >> R7
> >>
> >> 820 ohms
> >> R2
> >> R5
> >> R8
> >>
> >> 1.8K ohms
> >> R3
> >> R6
> >> Rx (this is the resistor soldered to R7 and the GPIO1 Connector)
> >>
> >> * * * Bottom Right
> >>
> >> 2K Red-Black-Red-Gold
> >> R17
> >> R14
> >> R12
> >> R11
> >>
> >> 1K Brown-Black-black-Brown-Brown
> >> R15
> >> R16
> >>
> >>
> >>
> >>
> >> On Jul 9, 2015, at 9:31 PM, John B <trymyz at gmail.com> wrote:
> >>
> >>> Steve,
> >>>
> >>> Are you referring to Luis' RGB2VGA board?  The reason I ask is I
> >> literally
> >>> (15 min ago) just finished assmebling my board.  I used the resistors
> he
> >>> outlined on his page under the "Modifications" section.
> >>> https://sites.google.com/site/tandycocoloco/rgb2vga  Are those the
> >>> resistors that produced the video jitter?  If so, can you give us the
> new
> >>> values that fixed the issue?
> >>>
> >>> Thanks,
> >>>
> >>> John
> >>>
> >>> On Thu, Jul 9, 2015 at 11:45 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!!!
> >>>>
> >>>> --
> >>>> Coco mailing list
> >>>> Coco at maltedmedia.com
> >>>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>>>
> >>>
> >>> --
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> >>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>
> >>
> >>
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> >>
> >
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