Dreamcast to arcade monitor: Complete (update)

[Frosty]

I've done a good amount of searching and found some good answers, but had a few remaining questions regarding attaching a Dreamcast to a standard resolution arcade monitor...

I recently purchased a Dreamcast VGA cable (see below), but I don't think this alone will allow me to hook up the Dreamcast to the monitor. Most threads I've seen (for example, this one) talk about a VGA box that needs to be hacked to output the 15hHz signal for the arcade monitor. Is this a requirement or will the cable I have--once stripped down and hacked for RGB & sync--work on its own?

[richms]

Is there any reason you cant get a scart cable and use that? I recall seeing a schematic for a sync seperator somewhere online that used an off the shelf chip and a handfull of other components if you need to go that far.

[Frosty]

I guess I could...but I'm here in the States and want to see if I can get this baby up and running without buying any additional parts.

[Dave_K.]

Although possible, I imagine hacking that VGA cable pictured would be much more difficult than hacking a vga "box".  What you need to do is remove one of the wires from ground, which means you have to tear into it somewhere.  Its easy to open up a vga box...I don't know how you will open this cable and do it.

Unfortunally, you'll be on your own.
Good luck.

[Dave_K.]

Is there any reason you cant get a scart cable and use that? I recall seeing a schematic for a sync seperator somewhere online that used an off the shelf chip and a handfull of other components if you need to go that far.

You can certainly hack a scart cable, but building the LM1881 circuit is usually more technical than people on this board can handel.  On the other hand, unscrewing a VGA box and snipping one wire is about as simple as you can get.

[Frosty]

Dave--

Yeah, I thought this was the case.

[Dave_K.]

What you have there is a "VGA" cable...so it grounds out both pins 6+7 on the dreamcast AV connector, which enables 31khz output.  If only pin 7 is grounded, then the cable will output 15khz.  The hack for the VGA box is to snip wire #6 (so it no longer connects to the Dreamcast AV connector).

This is all covered in the Game Consoles FAQ on this site (I wrote it back in 2002).  I think some people don't even know the rest of this site exists.
http://arcadecontrols.com/arcade_consoles.shtml#dc2arcade

[Frosty]

Thanks for clearing up the confusion--I thought that the 6/7 ground pins had something to do with the 15/31 kHz signal, but should have looked a little further on the site <grin>.

I'll post again with the results of the progress...

[forbiddenlyrics]

Snipping wire 6 on my VGA box worked great for me and I got my dreamcast working on my arcade monitor on my first try. I don't know about the VGA cable you are you using but I assume it is pretty similar to a VGA box. If you need any help just PM me and I'll try my best!

[Frosty]

Thanks Forbidden...I'm gonna give this a shot at some point this weekend and see how it goes.  I'll post with details...

[stellarola]

Once you tear into the cable, be sure to use a multimeter to check which pin it tis  .

[Frosty]

For anyone who's interested, here's the results of this weekend's work.  More details on the next post...

[Frosty]

Well, after tearing into the Dreamcast VGA cable, the results are pretty good...

First, I removed the 15 pin D-sub connection from the cable and mapped the wire colors to the corresponding outputs (multimeter not available to me at that point).

[Dave_K.]

That being said, anyone see any problems with having both the DC VGA cable and regular VGA cable wired at the same time?

Yes, you shouldn't be mixing the ground wires from one system (DC) with another system (PC).  If you have both on at the same time, you have a potential to do lots of damage to one or both systems!

I've herd it said a thousand times, that ground is a ground is a ground.  This is true, only if your ground is referencing a single power source.  The minute you introduce another power supply, now grounds can have different "potential".  This is what causes fuses to blow in one or both systems.

[Frosty]

Good point.  Aside from seperating the grounds (yeah, I heard the ground is a ground line, too), you think I'd face any other issues?

[Dave_K.]

Good point.  Aside from seperating the grounds (yeah, I heard the ground is a ground line, too), you think I'd face any other issues?

Well besides the ground lines, you don't want to mix any of the other lines as they may drain some of the sigal.  In my setup, I hacked a single VGA extenstion cable to my arcade monitor.  I then plug this cable into my vga box or pc.  Its that simple. 

Since your vga box is a cable unto itself, it complicates things as now you need a seperate cable for PC and DC.  Its not very friendly to reach behind the monitor and unplug/replug the molex connector for your particular setup.  So I'd recommend just getting a db9 switch box, and hacking one more extension cable like I did.  Then you can more easily switch between the two and keep them isolated at the same time.

[stellarola]

Dude, yea don't mix the wires like that. You should get a VGA switch box A/B style  .

[Frosty]

Here's a pic of the VGA cable with pin 6 removed for only a 15 kHz signal output.  Also, here's the list of the colors of the VGA cable and their corresponding output.  Each cable may have diffrent colors, but if it's the same model as I have, it will probably match up....

DC cable	Monitor
White	Ground
Green	R
Blue	G
Yellow	B
Orange	V sync
Black	H sync

[sammaz]

Dam ! thanx for the images Frosty!!!

I have the exact same cable and use a J-PAC ...just needed 3 220Uf caps on R,G,B but thanx to you I know exctly where they are now...Its one of those projects that have been on the backburner waiting for a nice easy diagram...I dont have a line checker so its been tough to do until now!

Thanx again!

J-PAC gives white image without (3) 220Uf caps on RGB because it gets overloaded...adding the caps is only necessary for J-PAC owners.

[Frosty]

Nice! Glad I could help.  I figured the colors on the cable are pretty universal...

Those are two good looking cabinets you have there.  That vertical candy looks great!

[TheOtherBob]

I'd like to thank you for the pics too.    I didn't look close enough at this thread while searching for ideas on hooking up my Dreamcast to my Daytona sitdown.... I thought I'd need to get an actual box type adapter.  But seeing how you just ganked pin 6 out like that seems simple enough.  I realize I won't easily be able to use it on a regular vga monitor after that but that won't bother me much.... if I ever need to, I'll just buy another adapter...

Now I just gotta figure out how to properly hack a Daytona steering wheel into the Dreamcast.....

[Mike615]

I would like to thank you for the pics and info also. I finally got the Dreamcast to work on my New Astro City.


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So I tried the SCART way and it's currently a failure. heh.
Then I tried using the VGA cable to JPAC with the 6 pin removed but got the rolling screen (cause the H&V sync wires weren't twist?) and it would fade out to black after some seconds. (http://forum.arcadecontrols.com/index.php?topic=9451.0) <-Like in this post.
So then came the scissors  as you can see. I cut off the end of the vga cable and did it this way.
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Also I read somewhere That it's not good to run just the arcade monitor and its bad for the power supply. So what are you guys doing?

*My ultimarc PS2 AV to JPAC the black color on screen is pretty dark? Is anyone else like this? Should I add the 220uF to R,G,B? And which color is what on the ultimarc PS2 AV. Like the R,G,B or is the actually wire the right color?

[Dave_K.]

So you are basically using your astro as a TV only? (since I don't see any controls hooked up to your fingerboard). 

Ideally you'd want some sort of load on the +5 (maybe also the +12) lines, so the regulator circuit in your power supply doesn't burn out over time without load.  You probably saw some of my old posts on this.  What someone suggested was to use a simple +5 (and maybe a +12) led/lamp/small-bulb wired to the board to give it some load.  I never finished building my custom DC->Jamma adapter, as I opted for an MGCD boad (which also has an audio amp onboard).

[Mike615]

I'm trying to use the original DC controllers and solder it to the buttons and joysticks. I'm  following the DC>JAMMA controller part, but I dont get it. I'm missing something.What does he mean by control line? What about ground? Anyone have any images of the dreamcast controller to joystick and buttons that I can see. I tried 1 button, I soldered that one wire from the DC controller X --> 1P button 1. Theres something else I gotta do. I think I'm missing something.

I think I'm gonna try that led/lamp/bulb thing. Aint the MGCD limited to some games?

[Dave_K.]

MGCD in 255 time mode is compatible with all games.

I believe what you read was that each button has a control line and ground line.  When these two touch, you get a button press.  Use a multimeter on continuity test to see which of the button contacts is ground, and which is control.  You only need to wire one ground wire to the jamma fingerboard since they all use the same ground.

Picture at the bottom of this page:
http://www.mameworld.net/pc2jamma/arc_dc4.html

[Frosty]

Wow...nice to see so many Dreamcast projects coming to fruition...

[TheOtherBob]

Hell I'll just throw my Daytona conversion (Thanks APfelon!) pic into here now that it's playing Crazy Taxi 2.....

Interfacing the steering wheel/pedals wasn't all that hard at all.  I was even able to use the existing amp in there to hook up the speakers to.  The original Sega mixer board had a nice set of rca jacks to plug into....

(the screen looks dark on the pic cuz of the flash)

Still gotta figure out how to do the shifter tho.... gotta get one first!

[Marky_1979]

I have this vga box and am wanting to use my Dreamcast with my arcade monitor can you tell me what I need to do to get it working.

I read the guide and noticed that on the pcb board the wires were numbered 1 - 15 I snipped the 6th (White) wire and removed the connector to the pcb. I tried it out and it didn't work have I missed something or missunderstood the instructions. Help Please

[Marky_1979]

Help please what do I need to do have I missed something vital here??





If you look closely you can see the wires are numbered 1 on the left and 15 on the far right I snipped the white 6th wire and tried to use vga box on my arcade monitor but its not working.

[clanggedin]

I thought you are supposed to snip the 6th wire on the connector that you plug into the dramcast. That's all I did to get mine working.

[Marky_1979]

Ok so I really have missunderstood this guide could you explain more please? and if possible add pics. I take it i'll need a whole new vga box?

[clanggedin]

Look at the 18th post in this thread by Frosty. He has a photo of the connector and which pin to cut.

[Marky_1979]

Ok cool does it matter that I have snipped this white wire? and any help on how I remove this pin? Pliers? *Update* I have removed this pin I get a picture now on my arcade monitor only issue now is it rolls from top to bottom can this be resolved?

[clanggedin]

I just used needle nose pliars and trimmed the plastic behond it so I could cut it completely out. I would re-solder the white wire you cut.

[Marky_1979]

Think this white wire is why its rolling? Any ideas on how to stop rolling guys?

[Samstag]

If you cut the vertical sync wire, this would cause it to roll.  I'm not familiar with your adaptor so I can't tell you whether the white wire really is the sync.

[Marky_1979]

I soldered the white wire back to its original connection on the board and tried it again but it still rolled what do you guys suggests I do?

[northerngames]

marky adjust your H and V on the monitor chassis

[Dave_K.]

I thought you are supposed to snip the 6th wire on the connector that you plug into the dramcast. That's all I did to get mine working.

Yes, this is exactly what the instructions say to do. 

Use a multimeter on continuity test to find which are the 6+7 wires (they will both read they are connected) and try cutting one of them.  The ordering of the wires on the PCB could be completely random or different than the AV plug end.

Also its not a good idea to test this mod directly on your arcade monitor as you can surely damage it sending a 31khz signal.  Test on a PC monitor, and if you get absolutly no signal (out or range) then test on your arcade monitor.

[Dave_K.]

Double post, sorry.