Dreamcast's are going crazy... Help!

[Link83]

The official Dreamcast RGB cable doesn't have the pin for Composite video wired up.

Actually your half right (No offence intended)

The official RGB Scart cable has the Composite pin connected, but the cable purposefully grounds one pin on the Dreamcast AV port to let the video chip know to output 15kHz RGB (RGB Scart) instead of Composite/S-Video. A similar thing happens when you enable 31kHz RGB (VGA Mode) which grounds two pins instead of just one.

Once RGB is enabled (Either 15kHz or 31kHz) Composite Video is purposefully disabled and replaced by a Composite Sync signal instead on the same pin. If a Scart cable didnt have a 'Composite pin' at all your TV would not be able to sync with the picture!

P.S. What the heck does FAMMYDODD mean?!

[^Katsu]

Actually your half right (No offence intended)

The official RGB Scart cable has the Composite pin connected, but the cable purposefully grounds one pin on the Dreamcast AV port to let the video chip know to output 15kHz RGB (RGB Scart) instead of Composite/S-Video. A similar thing happens when you enable 31kHz RGB (VGA Mode) which grounds two pins instead of just one.

Once RGB is enabled (Either 15kHz or 31kHz) Composite Video is purposefully disabled and replaced by a Composite Sync signal instead on the same pin. If a Scart cable didnt have a 'Composite pin' at all your TV would not be able to sync with the picture!

P.S. What the heck does FAMMYDODD mean?!

http://ntsc-uk.domino.org/showpost.php?p=1426776&postcount=1617

Cheers for the replies, will do some further investigation

[fallenangle]

I knew the official DC RGB cable had less pins but, of course, still has the composite pin for sync. I'd always assumed that for manufacturing reasons they'd just omitted the unnecessary audio and video output pins.

I wasn't aware, if that is what you're saying, that the DC won't output composite via SCART using the official lead. What about non-DC RGB cables?

Like many, I suspect, I use a fully wired version with AV block. Took me ages to find a couple which worked (I've bought 4 which turned out to have manufacturing faults).

[Link83]

http://ntsc-uk.domino.org/showpost.p...postcount=1617

Cheers for the replies, will do some further investigation

Thanks for the link!

I knew the official DC RGB cable had less pins but, of course, still has the composite pin for sync. I'd always assumed that for manufacturing reasons they'd just omitted the unnecessary audio and video output pins.

A fully wired Scart cable should have 21 pins/connections, but you only actually need 9 for an RGB connection, so many console manufacturers leave out all the unnecessary pins. For RGB you only need:-

3 Pins for Red, Green & Blue
2 Pins for Audio Left and Right (Stereo)
2 Pins for Switching Voltages (Switch to AV1/RGB channel)
1 Pin for Composite Video/Sync
1 Pin (or more) for Ground

A full scart pinout can be found on Wikipedia here (Down the right hand side):-

http://en.wikipedia.org/wiki/Scart

As you can hopefully see, all the other pins are for things like extra grounds (8 possible grounds!) and Composite Video and Stereo Audio output from your TV. Scart is actually bi-directional with Composite Video and Stereo Audio, eg. you could connect a fully wired Scart cable from your TV to a VCR Scart input to record the composite picture and sound - although I have never seen anybody really use it this way!

Any game console Scart cable you buy that has all 21 pins in it wont be using them all.

I wasn't aware, if that is what you're saying, that the DC won't output composite via SCART using the official lead. What about non-DC RGB cables?

Yes the Dreamcast doesnt output a Composite picture at all when using an RGB Scart cable (It doesnt matter if its a first or third party cable) If the Dreamcast is outputting RGB you cant have a Composite picture aswell. The Composite Video Pin still has to be connected though as your TV gets the Sync signal from it. (RGB always has to have a Sync signal aswell, and Scart TV's usually 'strip' this Sync signal from the Composite Video signal)

On your second point, do you mean for games consoles other than Dreamcast? If so, then yes all other games consoles seem to continue to output a Composite Video signal aswell as RGB - the Dreamcast is the only console I know of that decides to disable Composite Video when RGB is enabled - no idea why! I can only assume the video chip can only do one or the other. There is nothing wrong with just a Composite Sync signal though (except for the fact you cant watch the Composite picture)

Like many, I suspect, I use a fully wired version with AV block. Took me ages to find a couple which worked (I've bought 4 which turned out to have manufacturing faults).

I have read that alot of people choose to buy a scart cable with an AV block in order to connect the sound to an amp/reciever, but before I bought a proper scart switcher that has left and right phono outputs, what I used to do was use the spare Scart socket on my TV (Usually the second [or third] scart socket that only supports S-Video and Composite) and connect a 'Scart adaptor' up to it that has a 'input/output' switch, like this:-

http://www.ebest24.co.uk/images/products_images/unfurl/ebest24b548em.jpg

Then I use a straight though left and right phono cable direct to my amp for the sound, and then switched the adaptor to 'output' to get stereo sound from any Scart device connected to my TV! (Actually, my Scart adaptor was labelled backwards and I had to select 'input' to get the sound 'output' ) Im not sure if this method would work for all input types though (eg Component, S-Video, etc) but it certainly worked for all my devices connected by Scart.

btw, I have pictures of the insides of the Official Dreamcast Scart cable if anybody is interested...

--------------------------------------------------------------

Back on topic, I really dont know why those specific games are jumping back to the main menu - it does sound alot like the Dreamcast 'resetting problem' but why it would only happen on certain games at certain points is beyond me!

Is it possible that the GD drives are dying, and that they are only able to read certain sections of the disks?

The whole 'no support for RGB Scart cables' thing probably applies to a few of those games (Pretty sure JPN PenPen and SFZ3 dont support RGB Scart) but the others shouldnt work abit then stop part way though! They should either work or not work with the RGB Scart cable, if that makes sense!

Anyway, sorry for such a long post - I hope it helped somewhat

[JamesS]

Yes the Dreamcast doesnt output a Composite picture at all when using an RGB Scart cable (It doesnt matter if its a first or third party cable) If the Dreamcast is outputting RGB you cant have a Composite picture aswell.

I thought some 3rd party leads did carry both? The DC video output has a composite sync pin and a separate composite video pin.

It's a while ago now, but I thought that the official lead wired to the composite sync, but that some 3rd party leads used the composite video pin, and that the composite video pin still carried a picture when RGB was enabled.

[Link83]

I thought some 3rd party leads did carry both? The DC video output has a composite sync pin and a separate composite video pin.

It's a while ago now, but I thought that the official lead wired to the composite sync, but that some 3rd party leads used the composite video pin, and that the composite video pin still carried a picture when RGB was enabled.

OK you have got me wondering now!.... i'll have to double check this <goes to find his official DC scart cable and a multimeter>

...But just to say, I previously read about Composite Sync replacing Composite Video at the GamesX forums from some very knowledgeable people...

<EDIT> Nope, just confirmed that Composite Video isnt present when using an Official Dreamcast Scart cable - you will just get a black picture with sound which is just your TV locking onto the Composite Sync signal. I checked with a third party cable aswell (White one with AV block) and got the same result.

<SECOND EDIT> Just checked aswell which pins are used on the official cable - as you suggested Composite Sync is used (Pin10), but Composite Video isnt (Pin13) There isnt even a pin on the DC plug end for it! Which means there was never even any possibilty of me getting a Composite Video picture.

I suppose its possible for other third party cables to try and use the Composite Video pin instead - however if Composite Video is totally disabled when using RGB as I have previously read, then these RGB cables would not work properly as the TV would not have any Sync signal to lock on to - perhaps this is what fallenangle has experienced with his faulty Dreamcast Scart cables?

[Papercut]

The official RGB scart cable doesn't carry composite video, only sync.

It also notifies the Dreamcast that an RGB cable is connected, hence some games then behaving differently.

There were third party scart cables that had a phono socket block part-way down the cable, but the ones I saw didn't also carry RGB.

[Link83]

The official RGB scart cable doesn't carry composite video, only sync.

It also notifies the Dreamcast that an RGB cable is connected, hence some games then behaving differently.

There were third party scart cables that had a phono socket block part-way down the cable, but the ones I saw didn't also carry RGB.

Cheers for the info, just confirmed it for myself

So there were third party Scart cables made that only carried Composite? I wonder how many people think they are using RGB when its just Composite over a Scart connection...

[fallenangle]

Thanks Link83 for the extensive reply but I do know about SCART cabling and the pins used/required. My questions were specific to the ODC RGB SCART cable in relation to the OPs problem.

BTW the ODC RGB cable is the only console cable I know which actually has the unused SCART plug pins removed.

After I posted I also remembered I did already know that the ODC RGB SCART cable doesn't carry a composite signal as well as RGB. That is one reason why the one I bought is sitting in it's original box in my loft now.

The independent RGB DC SCART cables I've bought have all had the full compliment of pins both ends (whether wire up or not they're still there) and happily carry both RGB and composite signals, in the latter case also via the AV block too.

What you and the others here have said though about the pin outs of the DC might explain some of the problems I've had with DC RGB SCART cables with AV blocks. I've just had the thought that those cables might have been wired up just to give composite via the AV block and only RGB via the SCART plug. Is that possible?

My preferred method of getting audio out of a DC or any other SCART console cable is now not to use the inbuilt AV block cables at all. I use a separate quality SCART audio L/R breakout block. Very useful, particularly if it is one with a switch and S-Video input and I have found far less prone to cross-talk interference even when used on a cable with an inbuilt AV block.

[Link83]

Thanks Link83 for the extensive reply but I do know about SCART cabling and the pins used/required. My questions were specific to the ODC RGB SCART cable in relation to the OPs problem.

Sorry, I didnt realise

BTW the ODC RGB cable is the only console cable I know which actually has the unused SCART plug pins removed.

Nintendo does the same for all their official SNES, GameCube and Wii RGB Scart cables - they dont have all the pins either.

In fact in some ways its beneficial to have just the necessary pins as then theres zero chance of crosstalk from the scart output pins (A common problem on fully wired scart plugs which if poorly shielded can often have ghosting on screen due to the output signal crosstalking with the input signal)

The independent RGB DC SCART cables I've bought have all had the full compliment of pins both ends (whether wire up or not they're still there) and happily carry both RGB and composite signals, in the latter case also via the AV block too.

Curious to know if these cables definitely show an RGB picture and not just Composite? (As Papercut said) I only ask as I have just double checked with someone who really knows their stuff on the Dreamcast, and they have confirmed that Composite Video and S-Video output is disabled when in either 15kHz or 31kHz RGB modes. Does your TV have an 'RGB channel' or any way to see what the incoming signal actually is?

In curious as to why having all the pins on the plugs or not is important? To me it just makes it even more difficult to know what connections the cable supports (As they wont all be wired up)

What you and the others here have said though about the pin outs of the DC might explain some of the problems I've had with DC RGB SCART cables with AV blocks. I've just had the thought that those cables might have been wired up just to give composite via the AV block and only RGB via the SCART plug. Is that possible?

I dont think so, not unless the cable has a switch - either pin 7 is grounded and you get RGB, or its not grounded and the cable is only capable of Composite (or S-Video) So unless everything I have read is wrong im not sure how both RGB and Composite Video would be possible from a Dreamcast scart cable (Without a switch at least) It would have to be wired for one or the other, but not both.

My preferred method of getting audio out of a DC or any other SCART console cable is now not to use the inbuilt AV block cables at all. I use a separate quality SCART audio L/R breakout block. Very useful, particularly if it is one with a switch and S-Video input and I have found far less prone to cross-talk interference even when used on a cable with an inbuilt AV block.

Thats sounds abit like what I used - it means I can use higher quality original Scart cables as opposed to third party ones just for the AV blocks.

-Sorry to the OP for taking this thread off topic!

[Papercut]

On the SCART end the same pin is used for composite sync or composite video - a TV will take the sync part of the signal from composite video on that pin, if that is what is provided by the source device.

On the DC side composite sync and composite video are separate pins:

http://www.gamesx.com/wiki/doku.php?id=av:dreamcastav

I don't know if enabling RGB disables composite video or not. If not, there is nothing to stop third parties using composite video instead of composite sync in their RGB scart cables.

The third party SCART cables I've seen either had the phono socket block and used composite video only, or had the same wiring as the official Sega ones, without composite video.

You'd think if it were possible Sega would have used composite video instead of composite sync in their official RGB SCART cable to reduce problem calls from people plugging their Dreamcast in to a SCART socket that doesn't support RGB (no picture), but who knows.

Enabling VGA (which is just prog scan RGB) disables s-video and composite video. although that makes sense as the horizontal sync is doubled so they wouldn't work.

[fallenangle]

Having all the pins present doesn't make a difference I was just saying that of what must be now at least 10 differrent independent brand RGB DC SCART cables I've owned all were fully pinned up both ends. I agree it would be better if they weren't for precisely the reasons you mentioned.

As regards the AV block - you say a switch would be needed but if the DC composite out and composite sync pins are separate as stated and the SCART cable was wired to connect the AV block video-out to the composite pin and the composite sync to SCART pin 20 wouldn't that work and bypass a need for a switch?

My TV is a bit unusual (JVC WS CRT) in that it is not PAL60 compatible (annoying with the DC) and when presented with a 60Hz signal via SCART defaults to composite even when using a a RGB enabled TV socket.

When I use my PAL DC with it at 50Hz it is definitely RGB (just swapping to a non-RGB socket makes that clear). The trouble of course comes with NTSC import games and using the 60Hz (PAL60) option with PAL games. However I discovered that with the DC-X boot disc I could get import games and PAL60 ones displaying properly if I just changed the format from NTSC to PAL or visa versa.

When I do this I'm 99% certain PAL games are running at 60Hz and surely the NTSC ones must be too. My point is that because of this TV's quirky response to 60Hz RGB/PAL60 neither can be in RGB (it looks good but it certainly doesn't look like RGB) yet I am using exactly the same DC cable. So the same DC RGB cable connected to the same RGB enabled socket does seem to be outputting composite.
If you or anybody else has an explanation as to how and why this is possible if what has been said about the DC and RGB cables is correct I'd be interested to know.

None of this helps the OP though so sorry to have gone off at a tangent like this.

[Papercut]

I know the DC-X disk switches to 60Hz for ntsc games, you can check this with Cool Cool Toon - at 50Hz the music doesn't play back correctly. Booting CCT with DC-X on a PAL DC gives you 60Hz, with Utopia or a chip gives you 50Hz (other ntsc games switch to 60Hz on boot so chip/utopia is fine, it depends on the game). My copy does this automatically, and choosing ntsc or pal I always seemed to get 60Hz with ntsc games (I don't think this option actually has any effect). There was a video out select menu (rgb, composite, s-video) if you held a button down though.

For normal booting PAL games when you have chosen 60Hz, can you force the TV to RGB to get it working? For pal60 you are normally getting black and white?

One way to know for sure whether the cable is RGB would be to try one of the Japanese games that refuses to boot with RGB Or crack open the scart plug (hopefully just a simple screw collar) and check the R, G and B pins are connected would give a pretty good idea.

I didn't think it was possible to change composite/s-video from pal60 to ntsc without the R422 hardware mod. A colour picture at 60Hz when pal60 is normally black and white should mean it really is RGB. Some CRT sets do look a lot worse at one of 60Hz or 50Hz, RGB or not, perhaps that is the reason.

Tangents are good. Just think, in a few years time we will be able to discuss the pal/ntsc compatibility problems of the PS3.

[^Katsu]

Ok i'l read thru that techy shizzle 2mo, but I picked up MK Gold (PAL)... And this plays fine on the PAL console but, DCX JAP wont go past the insert disc screen

[Link83]

As regards the AV block - you say a switch would be needed but if the DC composite out and composite sync pins are separate as stated and the SCART cable was wired to connect the AV block video-out to the composite pin and the composite sync to SCART pin 20 wouldn't that work and bypass a need for a switch?

I see what you saying, but I really cant see how that would work. If the Dreamcast realy does disable Composite and S-Video output when in RGB mode (and I have been told that by more than one person) then it wouldnt be possible without a switch of some kind on the cable. Even if both the Composite Video and Composite Sync pins were wired up as you suggest, only RGB or Composite Video can be 'active' at any given time, not both - and this is determined by one pin on the DC's AV plug either being grounded, or not grounded by the cable, so unless there a switch on the cable you cant choose between the two.

The only concievable way I could see this working without user interaction is if the AV Blocks Composite plug has a switch below it (internally) so that when you insert the Composite phono plug it disconnects the Ground to Pin 7 - but this is very unlikely.

I cant say for certain what connection your really getting, I would imagine the only way to be certain is as Papercut said - use an import game that doesnt support the RGB scart cable and see if you still get a picture, or open the scart plug and take a peek (Although id imagine this method still wont give you a definite answer, as if the cable hasnt got pin 7 grounded on the DC's AV plug, and also uses the Composite Video wire aswell, then even if the RGB wires are all connected it wont be RGB!) Is there any way you can test your Dreamcast setup on another TV, perhaps one that can tell you what signal is being recieved?

Also as Papercut said - its not unusual for the picture to look 'better' (or worse) when in 50Hz mode - either because the black borders are compressing the picture and giving the impression of extra detail, or because the console is outputting 576i 50Hz as opposed to 480i 60Hz so has extra lines (Although this is not the case with the Dreamcast) Sometimes its simply because your TV is better at handling 50Hz or 60Hz signals.

The other thing to bear in mind is that RGB is neither PAL nor NTSC, so you should never get a black and white picture if your using RGB. Your TV might not like 50Hz or 60Hz, but it should still be in colour, and if it isnt you'll know that it isnt RGB.

Forgive me if you already knew any of this, im only trying to help.