Dreamcast Internal VGA Mod

Dreamcast Internal VGA Mod

August 9, 2012 · by Pete · in , ,

The Dreamcast picture in VGA is stunning, the cost of VGA boxes is rising and falling all the time.  It is quite easy to make your own VGA box or even add a VGA out socket onto your console.  Only a small number of parts are needed so it’s quite cheap :)

This is basically 99% the same as the guide on DCEMU, I did alter it a bit as when I plugged in an RGB lead it also grounded Pin 6 on the DC motherboard which then enabled VGA mode again and caused my TV some problems!  So instead of linking pins 6 and 7 and then grouding them, I kept them seperate and grounded them individually (still using a single switch – a double pole, double throw switch).

So here’s my slightly modified diagram, pin 7  labelled as RGB Select, and a different switch used.

DC VGA Diagram

I can’t find the original post now, but I’m sure that ptr.exe on DCEMU also posted a stripboard layout for the above diagram.  I did scribble it down on a piece of paper, I reversed it so that I could hide it in the case a bit easier and leave room for a modchip.  Here’s my slightly modified design.

 

Here’s a picture showing you the necessary solder points on the back of the DC motherboard (again, source from DCEMU, I’ve marked some extra Ground points you may want to use, you can also see I have added some solder to the pads to make soldering easier later on – oh, and I’ve soldered the audio wires also!) (second picture by Link83 :)  cheers)

DC VGA Pinout

DC VGA Pinout (link83)

Finally, a picture showing all the components

DC VGA Components

First prepare the stripboard, 11 holes wide and 7 holes tall.  Make some cuts/breaks as shown in the diagram above and the following photo.

DC VGA Cutting the Board

It’s a very simple stripboard (great design by prt.exe), soldering up should be quick, here’s the diodes and resistors soldered on.

DC VGA Resistors and Diodes in Place

Followed by the capacitors and the underside of the board.

DC VGA Capacitors in Place

DC VGA Capacitors in Place

Next up I soldered the VGA socket, the following photo isn’t very clear – but I put some solder in the holes on the back of the pins, I also linked up the ground points using a cut off piece of resistor leg.  After that it was just heat the solder up and put the wires in the holes.

DC VGA Linking Ground on Socket

DC VGA Socket Wired Up

Using the photos, diagrams and info above solder up the wires for the VGA signal, VGA switch and if needed Audio.

Here’s how I wired up my VGA switch

DC VGA Switch

I *think* you could use the standard DC composite lead and get sound from that, BUT I decided to mount a 3.5mm audio socket on the back of my console.  Here’s how the socket I bought needed to be soldered up

DC VGA Audio Socket

Here’s my motherboard soldered up, it took me a while to decide how to route the wires (more info on that in a moment)

DC VGA Wire Routing

DC VGA Wired Up

I made this hole in the bottom metal shielding so that VGA wires can escape without getting squashed (I also insulated it so that they don’t snag on the edges).  The Audio and Switch wires come up at the rear of the console by the modem connector.

DC VGA Wire Route Modification

DC VGA Board Installed

Now it comes to mounting the sockets and switch, I forgot to take many photos of this bit, IF I was doing it again then I would have mounted them all a little bit higher, in this position the interfere with the metal base of the GD-ROM drive, I had to hack away at it to get it all to fit in.  I glued the wires in place just to strengthen them.

DC VGA Glued Wires

DC VGA Finished Sockets and Switch

Again, here’s the original guide that this is based on, I just altered it to suite my needs but you might find my page helpful too!

Just a few notes

On my Samsung LCD the image shifts to the left (or was it right?!) when the DC is in VGA mode, it doesn’t do this on my PC Monitor or on a mate Hanspree TV (I have since found out it does this with a VGA box too, so it’s the TV rather than this mod). I think it would be possible to do with without a switch by utilising the ground points on the VGA socket and linking them up to AV pins 6 and 7 (instead of linking the VGA ground pins together).

Summary of Components needed

  • 1 x Double Pole, Double Throw switch
  • 2 x 1N4148 Diodes
  • 3 x 220uf Capacitors
  • 2 x 4K7 ohm Resistors
  • 2 x 150 (or 100) ohm Resistors
  • 1 x female HD 15 socket
  • 1 x  3.5mm audio socket/2 phono sockets (something for Audio!)

 

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