RGB to VGA pin out?

Sam Latella

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Dec 3, 2010, 6:24:01 AM12/3/10

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Hi,

I'm looking for drawing or diagram which shows the correct pinouts for a RGB
video cable to a VGA cable. I've just purchased the RGB/CGA to VGA
converter to get my IIgs to run off a VGA monitor.

So far the results are fantastic on bootup... to a VGA monitor. However,
some of the colours are off and I think I have my pinouts wrong on the cable
I'm using.

Any help would be greatly appreciated.

Thanks,
Sam

IUnknown

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Dec 3, 2010, 9:29:56 AM12/3/10

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If some of the colors are off, but others are fine, then your pinouts
should be OK.

RGB signals the three primary colors of red/green/blue on separate
wires, and if one of them was mis/disconnected, *all* non-primary
colors would be affected.

What model/brand of converter did you purchase?

Sam Latella

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Dec 4, 2010, 6:50:09 AM12/4/10

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The converter I have is a rgb/cga 15khz to vga converter. It is the popular
model being sold on ebay (whitebox). I suspect that one or two of the
pinouts is wrong, but have no diagram of the crossover between rgb and vga.

Sam

Toinet

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Dec 4, 2010, 8:19:10 AM12/4/10

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Hi,

IIgs RGB pinout:
http://stason.org/TULARC/pc/apple2/faq/16-026-What-are-the-specs-and-pin-out-for-the-GS-RGB-monitor.html

VGA pinout:
http://pinouts.ru/Video/VGA15_pinout.shtml

I hope it is correct, I am no HW guy...
antoine

Mark Frischknecht

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Dec 4, 2010, 2:15:42 PM12/4/10

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Here is the pinout I used to get my RGB to VGA converter working.

>> IIGS CGA to VGA Input
>> Pin 1 Gnd --------> Pin 5 Gnd
>> Pin 2 Red --------> Pin 1 Red
>> Pin 3 CSYNC ---> Pin 13 HSYNC / CSYNC
>> Pin 5 Grn ---------> Pin 2 Grn
>> Pin 9 Blu ---------> Pin 3 Blu
--
Close this world. txen eht nepO
|
Mark Frischknecht

Apple2Steward

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Dec 4, 2010, 4:33:45 PM12/4/10

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"Sam Latella" <pow...@macgui.com> wrote in message
news:powergs-1...@macgui.com...

> The converter I have is a rgb/cga 15khz to vga converter. It
> is the popular
> model being sold on ebay (whitebox). I suspect that one or two
> of the
> pinouts is wrong, but have no diagram of the crossover between
> rgb and vga.
>
> Sam

--snip--

Is it this one?
http://cgi.ebay.com/15Khz-RGB-CGA-Component-Video-VGA-Converter-Scaler-/350244621369?pt=LH_DefaultDomain_0&hash=item518c34cc39#ht_4557wt_934

Steven Hirsch

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Dec 4, 2010, 5:50:14 PM12/4/10

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On 12/04/2010 06:50 AM, Sam Latella wrote:
> The converter I have is a rgb/cga 15khz to vga converter. It is the popular
> model being sold on ebay (whitebox). I suspect that one or two of the
> pinouts is wrong, but have no diagram of the crossover between rgb and vga.

If you have stable sync and any of the colors are correct, then I doubt you
have a wiring issue. One thing to try: Use the IIGS composite video output to
supply composite sync to the converter. There are slight timing differences
between the raw sync and the corresponding information in the composite out.
Some folks have reported better results when using it.

Steve

Sam Latella

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Dec 5, 2010, 3:53:53 AM12/5/10

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Hi,

Yes, I have this one.

The reason, why I think the pinouts are wrong... is that I cheated a bit. I
used a ---mac adapter which goes from an rgb connection to a vga--- then I
added the rgb to vga converter on the end.

The mac adapters were given with some NEC Multisync monitors years ago, so
instead of creating my own cable I tested out the adapter first with the
converter. So, if the pinouts are not right on this mac adapter, I'll have
to create a new cable or source one out that would work with the IIgs.

Sam

Mark Frischknecht

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Dec 5, 2010, 1:21:04 PM12/5/10

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That
>
is the one i use. You can see the results on my LCD monitor here.

http://picasaweb.google.com/AppleIIguy/CGAComponentToVGA#

Sam Latella

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Dec 6, 2010, 9:20:28 AM12/6/10

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Great!

The Mac adapter RGB to VGA works the the way it should. The pinouts seem to
be right on... Now with with the rgb/cga to vga converter I get the same
results. The system 6.01 desktop looks terrible, but still useable (which
I'm not sure why it looks like that?). The rest of the programs look great
on a 22inch Samsung LCD monitor.

Sam

Mark Frischknecht

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Dec 7, 2010, 12:12:34 AM12/7/10

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Its due to how the iigs dithers colors.

That

Michael J. Mahon

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Dec 7, 2010, 3:01:00 PM12/7/10

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Mark Frischknecht wrote:
> Its due to how the iigs dithers colors.

In particular, it's because the video dot clock for SHR mode is
16MHz, not the usual 14.3MHz, so that the alternating blue-white
background pattern beats strongly with the VGA converter's video
sampling clock.

Search for IIgs VGA adapter in csa2 on Google Groups and you'll
find a long and winding discussion of this and other conversion
issues.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page: http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
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