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

Steve Batson steve_batson at yahoo.com
Mon Jul 20 09:00:46 EDT 2015 

John,

I agree. At some point soon, I'm going to put mine in a project case. When I do that, I may extend the POT out so it can be adjusted without closing the case and I'll do the same for the CoCo Applicable DIP switches.


> 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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