Building your own Video cable

[Starcat]

Hello!

 

I'm currently trying to build myself an own video cable for the Jaguar. However I ran into a few weird problems, I do not have an answer to yet.

I want to have a cable that outputs Scart (RGB), S-Video and Composite. Is this possible with a single cable or are they interfering somehow?

 

For now I'm focussing on getting Scart (RGB) and composite to work.

My problem is the following...

In order to get vertical sync, I seem to have to connect comp sync to one of the color signals (red, blue or green). However if I do that, my composite signal is messed up (the color changes accordingly to the color I connect comp sync to).

Also I do not get sound when using the scart connector, even though sound works using composite and the wiring *should* be correct. Somehow some singals of the scart connector seems to block out the audio.

Also I noticed, the Jaguar does only output audio when you also connect sync, so I guess it's related to that.

 

Sorry that I can't really be more specific. I was just hoping somebody here might have some experience building his own cable. And just to clarify, I looked at both the dev manual and the Jag faq schematics.

Doing it exactly as shown in the Jag FAQ does NOT work with my Stub Jaguar.

 

I'm assuming, while the red, blue and green signals are correctly, something is still wrong with sync or other signals.

Any help is very welcome.

 

Regards, Lars.

Edited March 27, 2010 by Starcat

[busterm]

Hello!

 

I'm currently trying to build myself an own video cable for the Jaguar. However I ran into a few weird problems, I do not have an answer to yet.

I want to have a cable that outputs Scart (RGB), S-Video and Composite. Is this possible with a single cable or are they interfering somehow?

 

For now I'm focussing on getting Scart (RGB) and composite to work.

My problem is the following...

In order to get vertical sync, I seem to have to connect comp sync to one of the color signals (red, blue or green). However if I do that, my composite signal is messed up (the color changes accordingly to the color I connect comp sync to).

Also I do not get sound when using the scart connector, even though sound works using composite and the wiring *should* be correct. Somehow some singals of the scart connector seems to block out the audio.

Also I noticed, the Jaguar does only output audio when you also connect sync, so I guess it's related to that.

 

Sorry that I can't really be more specific. I was just hoping somebody here might have some experience building his own cable. And just to clarify, I looked at both the dev manual and the Jag faq schematics.

Doing it exactly as shown in the Jag FAQ does NOT work with my Stub Jaguar.

 

I'm assuming, while the red, blue and green signals are correctly, something is still wrong with sync or other signals.

Any help is very welcome.

 

Regards, Lars.

 

 

Yes its possible bit cumbersome with all the solder points but nothing difficult. One very important thing to mention and this could just be my tv and not the fault of the jaguar. But When two video sources are plugged in they cancel everything out. For example If I have the Composit and Svideo both plugged into my TV no image will be displayed or sound. If I remove one then the image will display on either of the two. I have an RGB monitor but thats its only input so I cant test that theory out on it. But my RGB works fine and no issues with sound unless as stated above about to connectors.

 

It could be something simple as interference with your wires or the TV itself. I wouldn't assume the Stub Jag would be an issue but its a possibility.

[Zerosquare]

I want to have a cable that outputs Scart (RGB), S-Video and Composite. Is this possible with a single cable or are they interfering somehow?

No problem, you can have all the different output signals on the same cable.

 

For now I'm focussing on getting Scart (RGB) and composite to work.

My problem is the following...

In order to get vertical sync, I seem to have to connect comp sync to one of the color signals (red, blue or green). However if I do that, my composite signal is messed up (the color changes accordingly to the color I connect comp sync to).

The composite sync should be connected in parallel with either the composite video output, or to the S-video luminance output. I recommend using the composite video output, as that way you'll get a SCART output that supports both RGB and composite.

 

Also I do not get sound when using the scart connector, even though sound works using composite and the wiring *should* be correct.

Somehow some singals of the scart connector seems to block out the audio.

Also I noticed, the Jaguar does only output audio when you also connect sync, so I guess it's related to that.

The Jaguar outputs sound independently of how the video signals are connected, but some TVs mute the sound if they don't detect a valid video signal.

[Starcat]

Thank you.

Zerosquare, can you take quick look at the pinout and tell me which pins exactly I need to connect to get composite and SCART RGB at the same time? Because that's really what's most important to me.

[Zerosquare]

Here's the pinout used on the official SCART cables (which support both RGB and composite video). I figured it out using a multimeter.

 

Jaguar pin <-> SCART pin

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

9B <-> shield

6A <-> 16

11A <-> 8

4B <-> 15

3B <-> 13

7A <-> 11

7B <-> 9

5A <-> 7

4A <-> 5

11B <-> 20

10B <-> 18

1A <-> 6

1B <-> 2

2A and 2B <-> 4

Edited March 27, 2010 by Zerosquare

[Starcat]

Thanks a lot for the schmeatic, however I still have the problem, that my picture is out of sync. It's cycling all the time.

Do you know if there are any resistors / capacitors required to get a good signal?

[Zerosquare]

No resistors or capacitor are needed.

 

Have you checked your cable with a multimeter ? It looks like you have a broken wire or a bad connection.

[a8maestro]

I am building an (analog)RGB adapter for the Jaguar. At this time, it works perfectly on the ST Color Monitor.

 

Still working on the vga test.

 

Composite and svideo also work fine.

 

Rick

[Starcat]

No resistors or capacitor are needed.

 

Have you checked your cable with a multimeter ? It looks like you have a broken wire or a bad connection.

 

It's really weird, because it *should* work. I might just replace the wires again now that I know the exact pinout.

My TV says "no signal" even though I can see the picture cycling through. So I thought maybe for some reason the signal wasn't strong enough or it needed some pull up resistors or so.

 

Also on a sidenote, I noticed the composite picture gets quite some interference when using the cd unit.

I never used composite before, so is this common? I guess it might be?

 

Regards, Lars.

[Zerosquare]

At least composite video should work. Since there are only two wires (signal and ground), very little can go wrong. Have you connected the ground properly ?

 

No idea about the JagCD as I don't have one. It doesn't seem normal, though.

[Starcat]

The composite does work. I connected 9B to the shielding of the Scart connector, so that should be find as far as ground goes.

Of course each R / G / B pin also has its own ground connected.

[Starcat]

I resoldered the whole adapter, still no improvement. However there is one odd thing I noticed...

What I am building is an adapter with a cart connector (female) so I thought I could just plug in a standard scart cable and be fine. However is it possible that most scart cables, even those who claim to be full connected, actually do not connect the pins 1:1, but for example wire composite in to composite out, same is true for audio in / out?

 

Regards, Lars.

[Zerosquare]

Yes, most male-male SCART cables are indeed built that way (this is true for composite video and audio ; R, G and B signals are pin-to-pin since there is only one set of pins).

[Starcat]

I finally got it!

Seems like I had to switch the pins for composite / audio in / out. However that didn't fix my sync.

For some reason I had to connect Pin 8 and 16 on the Scart connector to get sync.

 

But all of the trouble was worth it. My picture is much better than it ever used to be. I used a flat ribbon Scart cable before, but now I can connect a properly shielded one.

Thanks for the help everybody!

 

Regards, Lars.

[Starcat]

Now I'm trying to get the svideo part to work as well. It shows the colors right, but there still are wrong (pink/bluish) colors next to it. Any idea what causes that? I never used svideo much, so I'm not sure. here is a picture of what the screen looks like.

Edited March 29, 2010 by Starcat

[Zerosquare]

Are you using a separate S-video input, or trying to use the SCART socket ? (you can't have both S-video and Composite/RGB together on the same SCART plug ; it's either one or the other).

 

Check that the chrominance signal (and its ground) is proprerly connected (it sometimes does this if it's not).

Also check if you are using the luminance and chrominance signals, and not the composite video signal by mistake.

[Starcat]

Thanks for the hint. I was trying to use the same socket. I think I'll stick with composite and Scart for now.