Help with the AV/Composite cable pin-out.

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Gollot
noob
Posts: 1

Help with the AV/Composite cable pin-out.

Post#1 » Mon May 30, 2022 2:29 pm

Hello people, I'm trying to "improve" my Dreamcast composite (RCA composite) cable with an original Xbox 360 composite cable that is in much better condition (My original Dreamcast cable is kinda mangled and it looks like crap on composite compared to other consoles on composite on the same TV (I already know that composite is the second worst video option after RF... composite generally looks pretty decent on CRT TVs that's where I use my consoles and other consoles don't look as noisy as my DC)).

So the pins that I have are pin 1 for ground, pins 2 and 3 for left and right audio, and pin 13 for composite video. I followed that and soldered the corresponding wires to the DC Cable video connector, tested everything with a multimeter, and looks like everything is fine but when I hook up the console I get no image at all, am I missing something? Do the DC cables have any extra hardware inside that I'm missing?
Here is a pic of the insides of the cable video port.

Image

and here is the pin-out I'm using for reference.

Image

Reasons why I have decided to make the cable myself (Everywhere I have asked people tell me to just buy a third party one lol) It will take months to get where I live, most third party cables are of a very low quality and lack shielding (Microsoft cables are known for being extremely well shielded and are often used to make cables for other consoles, I have done it for the Wii,PS2,OG Xbox)

Thanks for your time!

Odyssey113
shadow
Posts: 6

Re: Help with the AV/Composite cable pin-out.

Post#2 » Mon Feb 20, 2023 12:36 pm

Pin 6 may or may not have something to do with your issue as I believe it does some sort of signal selction at boot. I'm still trying to learn more about it though. I'm working on trying to solve a similar issue, more-so tying into how the console is trying to sync with either my VGA or my RGB tv setups...

I'd be curious to hear if you ever got anywhere with this.

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aldair
Metallic
Posts: 802

Re: Help with the AV/Composite cable pin-out.

Post#3 » Mon Feb 20, 2023 1:40 pm

I also use composite cable from the 360.

Image



Image

User avatar
aldair
Metallic
Posts: 802

Re: Help with the AV/Composite cable pin-out.

Post#4 » Mon Feb 20, 2023 1:44 pm

Odyssey113 wrote:Pin 6 may or may not have something to do with your issue as I believe it does some sort of signal selction at boot. I'm still trying to learn more about it though. I'm working on trying to solve a similar issue, more-so tying into how the console is trying to sync with either my VGA or my RGB tv setups...

I'd be curious to hear if you ever got anywhere with this.

-Pin 7 on GND is RGB.
-6 and 7 on GND is VGA.
Image

https://i.imgur.com/3kjRoDP.jpg


[img][img]http://i.imgur.com/VsYa9JR.png[/img][/img]
Last edited by aldair on Mon Feb 20, 2023 2:25 pm, edited 1 time in total.

User avatar
aldair
Metallic
Posts: 802

Re: Help with the AV/Composite cable pin-out.

Post#5 » Mon Feb 20, 2023 2:23 pm

Gollot wrote:Hello people, I'm trying to "improve" my Dreamcast composite (RCA composite) cable with an original Xbox 360 composite cable that is in much better condition (My original Dreamcast cable is kinda mangled and it looks like crap on composite compared to other consoles on composite on the same TV (I already know that composite is the second worst video option after RF... composite generally looks pretty decent on CRT TVs that's where I use my consoles and other consoles don't look as noisy as my DC)).

So the pins that I have are pin 1 for ground, pins 2 and 3 for left and right audio, and pin 13 for composite video. I followed that and soldered the corresponding wires to the DC Cable video connector, tested everything with a multimeter, and looks like everything is fine but when I hook up the console I get no image at all, am I missing something? Do the DC cables have any extra hardware inside that I'm missing?
Here is a pic of the insides of the cable video port.

Image

and here is the pin-out I'm using for reference.


Reasons why I have decided to make the cable myself (Everywhere I have asked people tell me to just buy a third party one lol) It will take months to get where I live, most third party cables are of a very low quality and lack shielding (Microsoft cables are known for being extremely well shielded and are often used to make cables for other consoles, I have done it for the Wii,PS2,OG Xbox)

Thanks for your time!

Pin 1 only on GND is not good, it needs GND from the metallic part of the connector.
Image

Odyssey113
shadow
Posts: 6

Re: Help with the AV/Composite cable pin-out.

Post#6 » Tue Feb 21, 2023 11:00 am

aldair wrote:
Odyssey113 wrote:Pin 6 may or may not have something to do with your issue as I believe it does some sort of signal selction at boot. I'm still trying to learn more about it though. I'm working on trying to solve a similar issue, more-so tying into how the console is trying to sync with either my VGA or my RGB tv setups...

I'd be curious to hear if you ever got anywhere with this.

-Pin 7 on GND is RGB.
-6 and 7 on GND is VGA.



Where exactly does pin 6 and 7 get it's grounding from in the normal boot process?

I have a 2nd DC I picked up that will not sync by default when using an RGB modded CRT, and it works on VGA (thru a kaico adapter), but it won't sync on first boot without unplugging and plugging back in the Kaico adapter. My other DC works perfectly with both setups.

Any thoughts on what could be causing that? The AV port looks in good shape and I know all my cables work, it's just this one DC.

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megavolt85
Developer
Posts: 1823

Re: Help with the AV/Composite cable pin-out.

Post#7 » Tue Feb 21, 2023 3:55 pm

Odyssey113 wrote:Where exactly does pin 6 and 7 get it's grounding from in the normal boot process?


pins 6 and 7 are connected directly to the GPIO of the central processor, BIOS and games read the state of these pins and turn on the desired video mode in the graphics library, and also write the value to the GPIO register AICA (Yamaha Sound Processor Unit), GPIO AICA are connected to the legs of the Digital Video Encoder , which are responsible for selecting the type of output signal and color coding

Odyssey113
shadow
Posts: 6

Re: Help with the AV/Composite cable pin-out.

Post#8 » Tue Feb 21, 2023 4:44 pm

megavolt85 wrote:
Odyssey113 wrote:Where exactly does pin 6 and 7 get it's grounding from in the normal boot process?


pins 6 and 7 are connected directly to the GPIO of the central processor, BIOS and games read the state of these pins and turn on the desired video mode in the graphics library, and also write the value to the GPIO register AICA (Yamaha Sound Processor Unit), GPIO AICA are connected to the legs of the Digital Video Encoder , which are responsible for selecting the type of output signal and color coding


I appreciate you explaining that.

With my explanation listed above, is there anything that would jump out to you as far as where to check? Nothing obvious I'm seeing. Port looks fine inside and out. My cables are known working 100% with my other DC.

I did actually do a full electrolytic cap replacement to this, and no major changes.

And this console does work fine on composite video, just refuses to sync with my RGB modded TV (that syncs luma) and then with the VGA it works, but only if I unplug/ then replug in the AV cord?, which I know is not recommended. Kinda at a loss on this one and don't know where to look anymore. I've checked continuity on a handful of components.

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megavolt85
Developer
Posts: 1823

Re: Help with the AV/Composite cable pin-out.

Post#9 » Wed Feb 22, 2023 6:05 pm

Odyssey113 wrote:and then with the VGA it works, but only if I unplug/ then replug in the AV cord


do you start the game with a VGA cable and unplug and plug the cable in the game?
or do you start the game with S-VIDEO and after that insert the VGA?

Odyssey113
shadow
Posts: 6

Re: Help with the AV/Composite cable pin-out.

Post#10 » Thu Feb 23, 2023 11:10 am

megavolt85 wrote:
Odyssey113 wrote:and then with the VGA it works, but only if I unplug/ then replug in the AV cord


do you start the game with a VGA cable and unplug and plug the cable in the game?
or do you start the game with S-VIDEO and after that insert the VGA?


I start the console with everything plugged in. I think I may have sorted the issue as semi-non existent. I think I have too many things hooked up in my chain and it's causing a delay of the sync on the VGA setup. Time to minimize it a bit I think.

Then on my scart setup I actually got my new switcher in the mail yesterday and it miraculously works well with this switcher, which still doesn't make a ton of sense, since my old DC was working fine with both setups with no issues ever, but hey I'm gonna call this "fixed" for now lol...

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