DCEmulation

dreamcast development • homebrew software • hardware hacking • indie games • emulators • and more!
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 Post subject: My VGA box from scratch!
PostPosted: Tue Aug 05, 2003 6:09 pm 
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DCEmu Crazy Poster
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Joined: Sun May 25, 2003 2:27 pm
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http://www.angelfire.com/gundam/geoffnaked/DCVGA_1.html

I never thought to order a RGB cable when I bought my VGA box, so I made a Dreamcast connector from two S-video cables...Now that I think about it, someone may have done this before me, but the extra wire on the connector looks pretty funny.

Anyway, I think this is a pretty good solution for people who want to build VGA boxes and have access to A/V cables or S-video cables locally and don't want to pay massive shipping costs for SCART cables.

And the link is not really a tutorial, just a documentation of my progress (I kind of only took pictures right at the beginning, and right at the end though)


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PostPosted: Wed Aug 06, 2003 12:10 pm 
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Insane DCEmu
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Joined: Fri Jan 17, 2003 2:42 am
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You wanna whip up a tutorial or somthing? Im interested in how you got this thing to work without using the 74HCT244 chip. Thanks.

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PostPosted: Wed Aug 06, 2003 2:13 pm 
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DCEmu Mega Poster
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Nice man. I might use some pics for on my site. Cool.

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PostPosted: Wed Aug 06, 2003 8:53 pm 
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DCEmu Crazy Poster
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Omigosh...I don't know if I can write a tutorial for this, I already gave the thing to my friend today.

I think the thing (with and without the chip) is explained here
http://www.dcemulation.com/phpBB/viewtopic.php?t=1782
And if you download any of the circuit diagrams from the links people have posted, I can explain what you need and what you don't need to make just the bare bones VGA box. Bare bones meaning it can only boot in VGA mode, and doesn't have the S-video and composite outputs, and no safety net if somehow you get the Dreamcast to send an invalid signal to an old monitor (for example, the reindeer image on Utopia 1.2)

Anyway, if you look at the picture of the Dreamcast connector with all the pin numbers, you only need 1,2,3, 6,7,8,9, and 14,15,16.

Pins 2 and 3 go straight to the proper pins on the headphone jack.
Pins 6 and 7 are connected straight to pin 1 (or to the metal covering of the Dreamcast connector, both are ground).
Pin 8 goes through a 150 ohm resistor to pin 14 of the VGA connector.
Pin 9 goes through a 150 ohm resistor to pin 13 of the VGA connector.
Pins 14,15,16 each go through a 10V 220 uF capacitor to pins 3,2,1 of the VGA connector respectively. (+) of capacitor is towards DC, (-) is towards VGA. I think 10V is preferable, I used 16V with no problem.
Pin 1 (or any other ground wires available, I had 3) connect to the remaining pin on the headphone jack, and pins 5-8 and 10 of the VGA connector.

Sorry if that might have been a pain to read, the schematic diagram for the thing is actually pretty dead simple without the chip. I don't have any proper tool for drawing these, maybe someone can do me a favour and make a simple schematic for this? Or maybe draw one for yourself on paper..

As for the Dreamcast connector itself, that's the tougher part, and I don't really think I can help with that. All I can say is I used 3rd party cables made by Performance, you won't really know if the cables you get can be used until you slice them up and have a look inside. But I think once you get the look inside, you'll know what to do ;) As long as the individual pins look like they can be removed and moved around you should be fine..

Well here's my lousy attempt at a schematic, can somebody please help me clean this up? Fear my moderately angry MS Paint skills.
http://www.angelfire.com/gundam/geoffnaked/images/dcvga/uglyVGA.gif


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PostPosted: Thu Aug 07, 2003 6:48 am 
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Soul Sold for DCEmu
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Sweet :mrgreen:

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PostPosted: Thu Aug 07, 2003 8:42 pm 
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DCEmu Veteran
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So what does VGA box do exactly?

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PostPosted: Thu Aug 07, 2003 9:02 pm 
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Jim Dandy!
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Joined: Thu Jul 25, 2002 7:48 pm
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Warmachine wrote:
So what does VGA box do exactly?
DC on the PC :mrgreen:


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PostPosted: Fri Aug 08, 2003 12:40 am 
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Jabba2442 wrote:
Warmachine wrote:
So what does VGA box do exactly?
DC on the PC :mrgreen:


oh ok :lol: . Thats pretty cool. Was it really hard to do?

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PostPosted: Fri Aug 08, 2003 2:04 am 
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Insane DCEmu
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Joined: Mon Jan 06, 2003 5:32 pm
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Jabba2442 wrote:
Warmachine wrote:
So what does VGA box do exactly?
DC on the PC :mrgreen:


DC on the computer monitor, actually.


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PostPosted: Fri Jan 30, 2015 8:08 pm 
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DCEmu Cool Newbie
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Joined: Sat Dec 06, 2014 7:14 pm
Posts: 10
Hi. Thanks for sharing. That's a cool hack and a great God-given skill, you're quite skilled.

I use the affordable but alright retrobit VGA box for the my Dreamcast (it'd be nice to have Adam Koralik's latest setup for VGA boxes and the biggest PC CRT Montor with the sharpest image- saving up for it. I'm on the no scanlines camp too).

How does this hack compare to boxes from Retrobit or Tomee (not so good they say) when it comes to image quality? If it's the same, I'd probably sell my retrobit coz' it's a bit expensive and build one myself too.

The links are gone (the schematics and the other links related to building it).

Thank you in advance.

God bless, Rev. 21:4


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