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

[Steve Batson]

Great tips Ed...Thanks!

On Jul 10, 2015, at 9:46 PM, Edward Snider <zippster278 at gmail.com> wrote:

> In that case I guess I'll have to change those resistors as well.
> 
> Electrolytics are well sealed, no problem there.  A transformer might take
> a while to dry out, I think I might avoid dunking that.  For the rare
> component that can't be submerged I usually finish the board except for
> those, clean the board, add those components and spot clean where they were
> installed.
> 
> - Ed
> On Jul 10, 2015 11:34 PM, "Steve Batson" <steve at batsonphotography.com>
> wrote:
> 
>> Ed, the recommended resistors do not provide the proper voltage levels for
>> the VGA circuit, that's what Roger found out after much painful research
>> and experimenting. Neither of our boards were stable with the design
>> recommended voltages. With Roger's recommendation, Both Roger's and mine
>> are Rock Solid.
>> 
>> I have the 91% Isopropyl myself, a little dispenser and a small acid
>> brush...works good, but I like our idea about soaking the board for a
>> bit...that might not be a good idea for all components would it?
>> Electrolytic caps, transformers, etc. Way back when, I used to use
>> denatured alcohol with the acid brush and it worked awesome.
>> 
>> 
>> On Jul 10, 2015, at 8:05 PM, Zippster <zippster278 at gmail.com> wrote:
>> 
>>> I’m following this thread with interest, as I’m going to be finishing up
>> theRGB2VGA boards that people had ordered from Kip
>>> to get that project successfully completed.
>>> 
>>> It is true that different monitors are more or less tolerant to certain
>> differences in signals, that could explain
>>> some of what is being seen here.
>>> 
>>> Regarding cleaning boards, 91% isopropyl alcohol works wonderfully.
>> What I do is submerge the boards in the iso in a small
>>> tupperware type container, soak for 10 minutes or so, brush them with a
>> toothbrush while in the bath, then rinse with fresh iso and air dry.
>>> Be sure to use the 91%, the lower concentrations have too much water in
>> them.  It’s available at drug stores, walmart, etc.
>>> 
>>> - Ed
>>> 
>>> 
>>>> On Jul 10, 2015, at 9:39 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.
>>>> 
>>>> 
>>> 
>>> 
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