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

[John B]

Steve,

I still have the recommended resistor values from Luis' design.
Unfortunately no one locally has the values you recommended so I am placing
my DigiKey order tonight.  I will just create another board since I have 2
spares.  Then I can really compare the two.  I have taken care of
recommendations 1-3.  I will pull that wire tonight.  Also, did you use the
.sof and/or .jic from Luis' Github page?

On Fri, Jul 10, 2015 at 10:39 PM, Steve Batson <steve at batsonphotography.com>
wrote:

> John,
>
> Have you changed the resistors yet, or are you using the resistors
> recommended for the design? I was seeing jitter, where the entire screen
> would jerk and occasional waves going through it mostly noticeable on the
> edges. Also, it didn't seem consistent, sometimes it was worse than others.
> Based on what Roger had found, it sounded like there were a number of
> issues being caused by the original resistor values. Voltage Levels were
> not what they should be. Also there was issues with the HSYNC and VSYNC
> again caused by original resistor values. Luis and posted on the FB page a
> response to one of my questions that some CoCo's are noisier than others
> and this may very well be true, but I'd guess symptoms could be worse on
> some systems then others which could be the combination of the CoCo and
> Monitor. From discussions with Roger about this and how he fixed it, I'm
> going to go out on a limb here and suggest that with his suggested resistor
> values, the video will most likely be crisp, clean and jitter free on most
> any CoCo and VGA monitor unless they have problems of their own.
>
> It was a bit of a pain in the butt pulling a bunch of resistors out and
> replacing them with Rogers suggested values, but I'd highly recommend it if
> you haven't done so already. It was totally worth it! If you have already
> replaced the resistors with the new values and are still having issues, I'd
> suggest the following:
>
> 1) Inspect your board and make sure you have no possible shorts. Clean it
> real good with alcohol or other good electronic board cleaner and
> thoroughly dry.
> 2) Check all the cables including power going to the board and make sure
> all is well
> 3) Make sure the ribbon cable isn't right next to a transformer including
> the CoCo power power supply (thought I am not having issues even if set the
> board right on top of the CoCo above the transformer). This probably is NOT
> an issue.
> 4) Remove wire I mentioned that was a ground fix.
>
> Anyway, let me know if you have changed the resistors yet or not. I'm very
> curious to see where you are at.
>
>
> On Jul 10, 2015, at 7:18 PM, John B <trymyz at gmail.com> wrote:
>
> > Steve,
> >
> > I tested the board out.  The display comes out fine, colors display
> > properly, etc.  However, the edge of any line looks slightly wavy.
> Hardly
> > noticeable.  This is more evident with graphics opposed to text.  Of
> course
> > I played with the trim pot, but that only helped so much.  Is this what
> you
> > experienced before u swapped the resistors?
> >
> > On Fri, Jul 10, 2015 at 11:36 AM, Steve Batson <
> steve at batsonphotography.com>
> > wrote:
> >
> >>
> >>
> >>
> >> No problem, Roger deserves the credit all this work. I just duplicated
> >> what he did and putting info here hoping it's helpful.
> >>
> >>
> >>
> >> I had no stock of resistors and trying to find just a few either wasn't
> >> economical or easy. Needless to say, I've got a pretty good stock now!
> >> :D
> >>
> >>> 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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> >>
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> >>
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> >>
> >>>>>>
> >>
> >>>>>>
> >>
> >>>>>>
> >>
> >>>>>> --
> >>
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> >>
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> >>
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> >>
> >>>>>>
> >>
> >>>>>
> >>
> >>>>> --
> >>
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> >>
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> >>
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> >>
> >>>>
> >>
> >>>>
> >>
> >>>> --
> >>
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> >>
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> >>
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> >>
> >>>>
> >>
> >>>
> >>
> >>> --
> >>
> >>> Coco mailing list
> >>
> >>> Coco at maltedmedia.com
> >>
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> >>
> >>>
> >>
> >>
> >>
> >>
> >>
> >> --
> >>
> >> Steve Batson
> >>
> >> Website: http://www.batsonphotography.com
> >>
> >> Facebook:
> >> https://www.facebook.com/pages/Batson-Photography/313748145356
> >>
> >> Gallery: http://gallery.batsonphotography.com
> >>
> >> --
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> >>
> >
> > --
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>
>
>
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