Sega Dreamcast VGA Mod

If you've ever had a Sega Dreamcast, you know how awesome of a console it was. I love the dreamcast, but I got rid of the TV in my bedroom. Crap. What was I ever to do? Why, hack it open of course! Oh, sure, I could just as easily go out and buy Sega's "VGA box" for about $30 This mod will tell you how (assuming you have some decent soldering skills) to add a vga port to the back of your Dreamcast, for considerably less than the cost of a commercial VGA box which does the exact same thing. No IC's are involved here, just regular components, like capacitors, resistors and diodes. I plugged my Dreamcast into my LCD monitor, and it works like a charm.

Tools Needed:
No. 2 Phillips screwdriver
Wire cutters/strippers
Soldering iron
Dremel + cutting bit (steel bur or cutting wheel works well)

Materials Needed:
3x 220uF capacitors
2x Silicon diodes
2x 4.7Kohm resistors
2x 150ohm resistors
1x Slide or toggle switch
1x Female VGA port
1x 3.5mm stereo audio jack
Electrical tape

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Step 1: Removal of the Top Cover.

Remove the four screws on the underside of the dreamcast. There will be one in each corner. If you have a modem for your Dreamcast, remove it to expose the 4th screw.

Flip the whole thing right-side up and take off the top panel. Make sure you didn't leave a disc in the drive (I made that mistake several times while troubleshooting).

Step 2: Remove the GD-ROM Drive.

Remove the screws holding the metal assembly to the other metal chassis. The whole GD-ROM drive assembly lifts out, metal chassis and everything. Don't lift out only the plastic part, take the whole thing.

Step 3: Remove the Power Supply.

Remove the screws that hold the power supply in place. Unplug that white connector that connects up to the power switch. After that, pull the power supply straight up off the chassis. The power supply just clamps itself onto 6 thick wire terminals, so you don't want to put any undue stress on either part.

Step 4: Remove the Metal Motherboard Shield.

Remove the ribbon cable from the controller plug connector board to the motherboard. Do yourself a favour and remove the fan power cable (which is being covered by my thumb in this picture). Remove the four screws that hold the board in place, but don't try to remove the board just yet. Remove the screws which secure the metal shield in place, and lift it off, enabling you to remove the connector board. You'll have to remove the plastic bezel as well.

Step 5: Remove the Motherboard

If there are any screws at this point, remove them. You'll have a much easier time if you lift it from the front of the board, as shown in the photo. In this picture, you can see the power connector I was talking about earlier, in the upper right-hand corner of the board. Don't worry about the rubber heatsinks on those two square chips, the heat-paste will keep it adhered adequately onto the chip. If it does come off, just put it aside until you're ready to put the Dreamcast back together. The heatsink is important. Your Dreamcast won't last more than about 10 seconds without crashing if it's missing (first-hand experience).

Step 6: Let's Go Over the Circuit...

The circuit we're going to use is made of reasonably standard components, so you should have no problem getting what you need from your local electronics supplier (in Vancouver, I highly recommend RP Electronics) You could probably get this stuff at the CrapShack, but you may have trouble finding 150ohm resistors. Everything else will be there, but will be overpriced.

Anyway, as for the capacitors, the negative side should go towards the VGA connector. All of the pins on the VGA connector marked with a black dot must be grounded. The ones with white dots are unused.

By the way, if you want to add an audio jack, just use pins 2 and 3 and wire that to the right and left terminals on the jack. Ground the ground pin on the jack. I can't tell you, by the way, which one's left and which one's right, so you have a 50/50 chance of getting it right. My stereo's messed, so I can't tell you whether I picked the right one.

Do yourself a favour and don't try to solder on the top of the board. Flip it over, and you'll see some solder dots that are spaced further apart. (It's like Sega made the Dreamcast easy to hack on purpose)

The pinouts and their corresponding numbers are the same on both diagrams.

Step 7: Now You Can Start Soldering.

Using the pinout diagram from the previous step, you can see that I don't have anything grounded in the first picture. I chose to take the ground and supply voltage from the power supply terminals just to make soldering a little easier (as seen in the second photo). By the way, that yellow stuff on the solder joints isn't flux, it's actually glue that I added afterwards to make the joints a bit more secure.

Now, I used wires about 20-25cm long, but that may have been a bit excessive. Not a problem, but make sure you have some cable ties if the wires are too long.

Step 8: Solder the Circuit

This is a real ratsnest of wires, but it works. I used standard strip-board to mount the circuit, although if you really wanted to, you could etch a printed circuit board. The wires are each threaded through a couple holes before they are soldered, just for added strength. After you've soldered all of the stuff to the board, cover the bottom of it with electrical tape to avoid shorting it out on something.

Don't solder the wires to the VGA connector until you've made a hole in the case in which to mount it. Thread the wires through the hole and then solder them to the connector. It's just easier to mount if you do it that way. Also, if you made the hole too big, the metal tabs on the VGA connector will cover the gaps.

Step 9: Reassembly

Follow steps 1-5 in reverse order, making sure you don't miss any connectors. Screw everything back in. If the heatsink came off, put it back on. Don't force anything, and make sure there's nothing that could short out the mainboard (like a loose screw underneath)

I routed the wires through to the front of the Dreamcast, and put the circuit board on the corner of the GD-ROM drive, where there's that little flat spot in front of the black plastic. Whatever works in your situation I guess.

Put the cover back on, and screw everything in place, and make sure the disc can spin freely when put in, otherwise you need to crack it open again and just move some things around until it fits well.

Mount the VGA port, VGA select switch, as well as the stereo jack, and plug it all in.

Step 10: The Moment of Truth...

Sweet, if you did everything correctly, you should be seeing video with all 3 colour channels. The first time I started mine up, it was missing the green channel. No problem, I just had neglected to cut some copper trace on the stripboard, and the green was shorting out on the blue capacitor. Whoops.

If it doesn't work, turn it off, flip the switch and try again. If it still doesn't work, a wire's probalby loose. Open it up again and double check all of your connections. If everything's connected correctly, check that you don't have a diode or capacitor installed backwards.

Wow, look at that detail! Well, you can't really see it too well because the exposure on my camera was set just a bit too long. I have yet to try it on a CRT monitor, but on my LCD, it works great. Give this mod a try with your old Dreamcast, and you'll be glad you did.

I've heard that in the commercial VGA box, there are op-amps on the audio outputs, but the sound will still work on this mod even if you don't add them.

By the way, I've read that you can do a mod extremely similar to this with the XBOX 360 (different pinouts of course. You can do your own research on that one). It won't work with the Wii, Gamecube, or regular XBOX, as none of those output in VGA natively, and I'm not sure on the PS3. This just shows one more example of how advanced the Dreamcast was for its time. I still say the Dreamcast had slightly better graphics than the Gamecube, but I won't fight anyone if they say otherwise.



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    61 Discussions


    1 year ago

    I don't have any 1n4148 diodes, but I have 1N4001s. Would that work or do they not switch fast enough?


    2 years ago

    Avete la capacità tecnica di un bisonte, una modifica del genere con quel casino e groviglio di fili è disarmante!


    4 years ago on Introduction

    Very very good instructables, i might do this after i do the heavenly light mode for my dreamcast

    1 reply

    Reply 3 years ago

    Any way of adding a scanlines option to this?


    4 years ago on Introduction

    This is a very useful instructable, i think i might make it for my dreamcast too


    5 years ago on Step 7

    Ma che cazzo di saldature fai...sono terrificanti


    6 years ago on Introduction

    220uF capacitors on these can they be electrolyte and wat voltage do they gotta be?


    6 years ago on Step 6

    thanks for the info bro!!!!


    7 years ago on Step 6

    Thanks for this instructable.
    The connector schematics are very useful.


    8 years ago on Introduction

    I suppose the alternative to actually making teh vga connections would be to simply get a vga box, rip it open, and just internalise everything, then it would be a lot quicker


    8 years ago on Introduction

    Personally I would have just bought the VGA box instead of opening up the dreamcast, but if this works it does. I still need to get a dreamcast though....


    8 years ago on Introduction

    On all the VGA boxes you can buy that I have seen, none of them have had op amps. They were all hard wired to both ends (rca and headphone jack) at the same time.

    Other than that, awesome write up. I should really do this, being as I will usually play my dreamcast on a pc monitor, which you have to do because once you start using the VGA output, you can't go back to standard signal again.


    I keep having an "Out of Range" message on my monitor, accompanied by khz values that vary from time to time.  Dunno what I'm doing wrong.

    3 replies

    yah.... Got the same problem here. Also Out of range. But i dont Understand why? Everything is soltered correctly, everything has contact, should work - but No, a f***ing out of range instead.

    Great ~_~


    Reply 9 years ago on Introduction

     Are you certain you didn't switch the h/v sync wires? Or bridge them? Do you have access to an oscilloscope to check the waveforms?


    Reply 9 years ago on Introduction


    unfortunately I don't have access to an oscilloscope, but I allready solved the Problem! It's because the RGB/AV Switch. I soldered the Cables wrong. I soldered it like this: Position 1: VGA with GND, Position 2: RGB with GND, but when you look @ the schematic, VGA AND RGB must be grounded mit GND!

    Now it just works fine ^_^


    9 years ago on Introduction

    This works! I just finished -- holy crap did it take me a long time to get it working. Almost all day today. I ran into problems when I wired it up with the H/V syncs running though the 150ohm resistors like a commenter said.. DON'T DO THAT. Follow the instructions in this instructable carefully and you can succeed. I'll try to follow this post up later with some photos of it running.