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

[John B]

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!!!
> >>
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> >>
> >
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