Stedy's RGB to SCART cable

[Richardsk]

I was thinking about buying the Amigakit scart, does it work as good as this one on LCD screens?

[Peter]

It seems as though most LCD work with Amiga scart cables but the picture quality varies considerably and there it becomes a bit "pot luck" as to how your screen will behave.

[alexh]

Originally Posted by Richardsk

I was thinking about buying the Amigakit scart, does it work as good as this one on LCD screens?

Their product in the past was not a fully wired cable.

[FOL]

Originally Posted by alexh

Their product in the past was not a fully wired cable.

Our product in the present is a fully wired cable.

[paulo_becas]

Well after being gone for a while i'm back again to the amiga scene and i have to say that a few things happened since then, like the new accelerator cards for A1200 an A600. Those guys from individual computers did it again, great work.
But this is not why i'm posting here, what i found out last December made me feel really stupid, i don't know if this is really new to the guys around here but i thought this could be helpful information for guys around who are struggling to make there Scart to RGB cable to work on an LCD TV.
The thing is that last December i recovered 2 Dreamcasts from certain death and when i plug them into my LCD TV i had a black screen and when i tried them in an CRT TV i had crystal clear image.
After sniffing around the web i found info about what most LCD TV Manufacturers do, and the thing is that if a TV has 3 or 4 scart connections probably they aren't all the same and the only scart connector that supports every type of signal (RGB included) is Scart 1 or AV1. I was connecting my amiga and Dreamcast into AV3 and when i tried the amiga on AV1 i had a perfect image, i've tested it with every cable i made from all the schematics that i could found (made 5 cables) even with the Amigakit cable and every single one worked perfectly with my amiga.
Pretty cool right?
After spending hours trying to understand why the cables didn't work the solutions was very simple, i even tried in several lcd tv brands like LG (2), Grundig (1), Crown (1), Sony (2), and they all worked perfectly in AV1, i tried in all scart entrances and none worked except AV1.
So i'm pretty happy about it, hope this info will be helpful.

[TomCrazy]

@paulo_becas
Great info, and I totally agree. I have noticed the same thing throughout the years, and CRT TVs are often like that too according to my experience. Actually, I can not remember seeing a TV that has RGB support on any scart connector other than AV1, regardless it being a CRT, LCD or any other kind of TV.
The TVs I have come across that has more than one scart connector usally has RGB/composite support on AV1 and S-video/composite support on AV2.

[FOL]

Originally Posted by TomCrazy

@paulo_becas
Great info, and I totally agree. I have noticed the same thing throughout the years, and CRT TVs are often like that too according to my experience. Actually, I can not remember seeing a TV that has RGB support on any scart connector other than AV1, regardless it being a CRT, LCD or any other kind of TV.
The TVs I have come across that has more than one scart connector usally has RGB/composite support on AV1 and S-video/composite support on AV2.

Your both correct, Some TV's do not support RGB on any other socket other than AV1 (Scart socket 1).

Normally, it gives at white or black screen, if not supported.

[Specksynder]

I bought a RGB scart cable from Amigakit one year ago.It works perfectly with old CRT TV but not with my monitor-tv Samsung 2333HD (No signal, black screen).
Hope that helps

[Djay]

I bought a Retrocomputershack RGB Amiga to scart lead and that "works" on my 22" Samsung LCD TV (which has just one scart socket)

by works i mean that there is a slight "interference" effect and the image wobbles very slightly most of the time

sure this isnt noticeable when your playing a game, but when using static images lets say drawing pictures in Dpaint for example it get annoying

i have ordered a new cable from Amigakit and added in the notes that it is for use with an LCD TV

hopefully, this will fix the problem

[Jope]

I thought this was pretty well known. :-)

It's not always AV1. Just try all the scarts in turn if you don't get a picture at first.

[paulo_becas]

Originally Posted by Jope

I thought this was pretty well known. :-)

It's not always AV1. Just try all the scarts in turn if you don't get a picture at first.

Now you know why i feel pretty stupid

[EreWeGo]

Thanks for the diagram Stedy, great stuff! I manage to build my own, and after a few false starts it worked on a VERY old TV I got hold of, (scart is not that common here in New Zealand)
However, I now have a problem: since my cable was testing fine, I decided to get a better TV with scart. A friend gave me his old UK Sony Trinitron KV-28LS36U 28" widescreen crt. Now when I connect my A1200 via the cart cable, although I get a clear picture, the colours are very dull - bright red looks more brown... Composite colours look fine, (just not as clear obviously), and other scart cables, (like the one I use from my MegaDrive), also seem to be okay.
I found some other articles mentioning that sometimes you need a 150Ohm resistor going from Amiga 22 to Scart8, which I also tried, made no difference...
If anyone has any ideas they'd be very much appreciated, or is it just the model of TV that's the issue - are some just not "Amiga-Scart" friendly?

[EreWeGo]

Another question/thought: Is it the type of TV rather than model, ie: Widescreen CRT?
I've seen an auction for $1 for another old TV, 28" RCA widescreen, and I don't want to get yet another space-consuming monster if it's going to have the same issue...

[EreWeGo]

*Update*: I tested my cable on another widescreen TV, a Panasonic, and after initially only getting a white screen, (Scart 1 was set to YUV, not RGB!), I had colour back on my Amiga!
So...there appears to be an issue with the Sony KV-28LS36U TV, whereby although I can get colour fine for my Megadrive via a scart connection, the Amiga looks dull/dark etc...
Anyone else had issue with Sony TVs?

[FOL]

Originally Posted by EreWeGo

*Update*: I tested my cable on another widescreen TV, a Panasonic, and after initially only getting a white screen, (Scart 1 was set to YUV, not RGB!), I had colour back on my Amiga!
So...there appears to be an issue with the Sony KV-28LS36U TV, whereby although I can get colour fine for my Megadrive via a scart connection, the Amiga looks dull/dark etc...
Anyone else had issue with Sony TVs?

Ahhhh, . Same TV as me. I have that sony and the cable I have (years old) works fine on it.

Must be something odd with that cable. Have to be fair, that was one of the last Sony CRT's and it was the best in my opinion for 28".
Never had one go faulty since their release, .

[EreWeGo]

Originally Posted by FOL

Ahhhh, . Same TV as me. I have that sony and the cable I have (years old) works fine on it.

Must be something odd with that cable. Have to be fair, that was one of the last Sony CRT's and it was the best in my opinion for 28".
Never had one go faulty since their release, .

...Dammit!
I thought I'd finally sorted the issue out and was ready to blame the TV, but if you have the same model and on't have problems...then it must be the cable, even though it works okay on some TVs?!?

I give up, guess I'll order a cable and see what happens!

[FOL]

Originally Posted by EreWeGo

...Dammit!
I thought I'd finally sorted the issue out and was ready to blame the TV, but if you have the same model and on't have problems...then it must be the cable, even though it works okay on some TVs?!?

I give up, guess I'll order a cable and see what happens!

Check your old cable wiring against stedy's diagram.

[EreWeGo]

Originally Posted by FOL

Check your old cable wiring against stedy's diagram.

OMG, thanks so much for the suggestion - I'd "thought" I'd used the correct resistor for the Amiga pin 10 to Scart pin 20, but there wasn't one!

I didn't have a 330 ohm, so used two 150 ohm resistors in series, and wouldn't you bloody know it - I know have colour displaying correctly!

Thanks again for your help and apologies for being a dumbass!

The other good news is now I can keep the Sony, as it's an awesome TV for a CRT!

[Stedy]

@EreWeGo,

Looks like the video decoder in your TV was rejecting the video signal. With a 300 ohm resistor on CSYNC and 75 ohm terminator in the TV and nominal 4.8V output, the TV was seeing a 1.2V signal. Now some older video decoder (SAA7114 for example) devices do not accept video signals greater 1.0V and so will reject the signal.

You may have highlighted a small flaw in my design. The 330 ohm resistor should be 390 ohms, to cater for the possibility that the CSYNC signal is closer to 5V! If I get the time at the weekend, will try an experiment on this.

Glad you now have a working system.

Ian

[EreWeGo]

Originally Posted by Stedy

@EreWeGo,

Looks like the video decoder in your TV was rejecting the video signal. With a 300 ohm resistor on CSYNC and 75 ohm terminator in the TV and nominal 4.8V output, the TV was seeing a 1.2V signal. Now some older video decoder (SAA7114 for example) devices do not accept video signals greater 1.0V and so will reject the signal.

You may have highlighted a small flaw in my design. The 330 ohm resistor should be 390 ohms, to cater for the possibility that the CSYNC signal is closer to 5V! If I get the time at the weekend, will try an experiment on this.

Glad you now have a working system.

Ian

Thanks for the explanation Ian, and a HUGE thanks for your work with this mod - it's awesome to be able to finally "retire" my old monitor, and play some Amiga goodness on a big screen!