Stedy's RGB to SCART cable - Page 6

phipscube · 01 June 2010, 22:39

Stedy,

I bought an RGB cable off ebay and had problems with it on my Samsung 40" HD ready LCD TV, the picture was a scrambled mess. After applying the resistors as per your diagram its now working fine. Thanks for your work

Stedy · 02 June 2010, 00:09

@phipscube

What resistors did you add to your cable?

It would be helpful to know so that I can add the information to the website and the original posting to help other users who may also have problems with ready made cables.

Ian

phipscube · 02 June 2010, 10:03

I used the exact values in your diagram. Would you like my TV model? If so, I can give it to you later when I get home from work

paulo_becas · 07 June 2010, 12:28

I give up...
I tried the cable of this thread, build it perfectly, and i get nothing from my Grundig Vivance LCD TV, i also tried the amigakit cable and nothing, i've tried 2 more schematics and still get nothing.

Anyone has one of this tv and do you manage to get the amiga to work via Scart RGB Cable?

KillaByte · 07 June 2010, 18:58

Quote:

Originally Posted by paulo_becas

I give up...
I tried the cable of this thread, build it perfectly, and i get nothing from my Grundig Vivance LCD TV, i also tried the amigakit cable and nothing, i've tried 2 more schematics and still get nothing.

Anyone has one of this tv and do you manage to get the amiga to work via Scart RGB Cable?

Are you sure your RGB output is working okay? If you own a multimeter you could try to measure CSync, R, G and B against GND to check that your port isn't dead.

rkauer · 07 June 2010, 20:29

Some TV sets does not have true RGB inside, just composite.

alexh · 07 June 2010, 21:13

I'd bet money rkauer is right at the SCART socket you're trying to use does not support RGB.

24 October 2010, 00:41

Evening All.

I have an old Amiga DB23 to SCART cable which I am trying to use with my CDTV and Panasonic Plasma. I have rewired it as per Stedy's drawing at the top of this post, except there are no wires between the three video grounds and the one logic ground. (there are no spare wires in the cable for these!) Despite this the picture quality is excellent, although the picture is offset up and left so I have lost the edges of the picture. Is the offset due to the missing grounds or something else?

Also, I haven't wired up the "optional composite video connector". If I were to wire this up and connect it to my plasma's composite video input would I have better results?

thanks

alexh · 24 October 2010, 09:12

No and no.

The grounds won't help with pixel timing and the "optional composite video connector" is to connect to the AMIGA side not the TV side!!

Use your TV's controls to try to re-centre the picture.

26 October 2010, 22:34

Quote:

Originally Posted by alexh

No and no.

The grounds won't help with pixel timing and the "optional composite video connector" is to connect to the AMIGA side not the TV side!!

Use your TV's controls to try to re-centre the picture.

Unfortunately my Panasonic plasma only has the function to adjust the horizontal and vertical picture position on the PC input not the SCART.

Presumably this is because generally any conventional SCART equipment would not require that adjustment. Do you know what the problem with the CDTV SCART signal is that causes the offset?

Thanks

alexh · 27 October 2010, 00:42

Nope. Have you tried anything else with RGB SCART on the same TV? Are they centred?

A friend has a 42" Panasonic Plasma and A1200 RGB works fine, centred fine. Yes I know there are many different models and they all use different electronics but....

orange · 27 October 2010, 13:15

I have the same problem with picture offcenter with Panasonic plasma TV. unfortunately the problem is that Amiga composite sync signal is "pure". usually csync signal in devices such as playstation and others, need some kind of decoding. and TV takes that delay into account. Amiga (and Amstrad for eg) don't need this 'decoding' so there is no delay.
there are hardware devices to introduce this delay, they are sold on internet. iirc they are called "scart shifters" or similar:
http://ntsc-uk.domino.org/showthread.php?t=100786

Stedy · 27 October 2010, 14:43

@gafstu

Can you get a picture of the offset picture?

A standard workbench screen with the border on, would be great as it will help me to estimate how many microseconds I need to shift the video by.

I have an idea for a simple circuit that will add a delay to the video sync that might fix it.

@Orange

Does the Playstation 2 exhibit the same issue?

I have a Playstation 2 packed away so I could use this to measure any signal offsets.

Video encoders add around 10us of delay, the hope is that by adding this, it is possible to offset the video accordingly. The descriptions here and on the ntsc-uk.domino.org site appear to back up the theory. Have seen similar issues on some high end equipment where we have needed to shift the video sync relative to the video data.

Providing the jet lag does not hit me again, I plan to play in the workshop later.

Ian

orange · 27 October 2010, 15:15

@Stedy

no, Playstation 2 picture is OK, as well as Wii.

27 October 2010, 20:51

@Stedy

I will get the screenshot at the weekend. If new circuitry is involved would it be easier to use an indivision ECS to give a VGA output? Presumably this wouldnt have the offset problem, and even if it did the PC input is adjustable on the panasonic plasma. Would VGA actually give better picture quality than scart anyway?

Stedy · 28 October 2010, 00:15

@Gafstu

The indivision ECS should be be a good solution albeit expensive.

Both the VGA output of the indivision ECS and the Amiga RGB output, via SCART are analogue waveforms. With good quality cabling you should see no difference.

I'm sure other users can testify to the quality of the indivision VGA output.Would like to keep this thread on topic relating to use a SCART socket/RGB input if possible.

Ian

31 October 2010, 20:44

@Stedy

I bought a CD32 SCART cable off ebay as the CDTV has an RCA composite out like the CD32. This cable gives a perfect picture from the CDTV with no offset. I am not sure why this works when the DB23 output is offset, but i'm not complaining as the problem is solved! Thanks for your assistance.

Ebay Item number: 320528976081

orange · 31 October 2010, 22:11

its simple. afaik, CD32 has no RGB output. so that cable is cheap composite cable.
the thing is, SCART has a lot of pins. so it can 'carry' RGB, CVBS, S-Video, audio...
picture is centered but its lower quality than RGB.

Stedy · 31 October 2010, 23:14

@Gafstu

Did you try the SCART cable but using the composite video output of the Amiga to SCART pin 20?

This uses the exact same video signal as your new video cable, going to the same input pin.

@thread

What I will do over the coming weeks, is collate the information I have on various Amiga video options into a guide, in a similar manner to my Amiga power supply guide. This will cover the various cable types and their relative merits, any adaptor boxes and what they achieve and some information on the PAL/NTSC modes of operation.

I may ask for some contributions on hardware I do not own to add it to the guide. Will release a draft version on my website for you guys later this year.

Ian

orange · 01 November 2010, 00:42

perhaps that would be solution; use composite out connector instead of pin 10 (composite sync)? because tv will then have to "strip the C-Sync signal from the Composite Video signal."

too bad it would make cable not so elegant.

i know that these panasonic TVs have a "service menu", but dunno if it has options to center picture.

24 October 2010, 00:41	#108
gafstu Posts: n/a	Evening All. I have an old Amiga DB23 to SCART cable which I am trying to use with my CDTV and Panasonic Plasma. I have rewired it as per Stedy's drawing at the top of this post, except there are no wires between the three video grounds and the one logic ground. (there are no spare wires in the cable for these!) Despite this the picture quality is excellent, although the picture is offset up and left so I have lost the edges of the picture. Is the offset due to the missing grounds or something else? Also, I haven't wired up the "optional composite video connector". If I were to wire this up and connect it to my plasma's composite video input would I have better results? thanks Last edited by gafstu; 24 October 2010 at 00:46. Reason: typo

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01 June 2010, 22:39	#101
phipscube WipEout Fanboi Join Date: Apr 2010 Location: Ringsted / Denmark Age: 48 Posts: 263	Stedy, I bought an RGB cable off ebay and had problems with it on my Samsung 40" HD ready LCD TV, the picture was a scrambled mess. After applying the resistors as per your diagram its now working fine. Thanks for your work

02 June 2010, 00:09	#102
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	@phipscube What resistors did you add to your cable? It would be helpful to know so that I can add the information to the website and the original posting to help other users who may also have problems with ready made cables. Ian

02 June 2010, 10:03	#103
phipscube WipEout Fanboi Join Date: Apr 2010 Location: Ringsted / Denmark Age: 48 Posts: 263	I used the exact values in your diagram. Would you like my TV model? If so, I can give it to you later when I get home from work

07 June 2010, 12:28	#104
paulo_becas Registered User Join Date: Feb 2010 Location: Porto, Portugal Posts: 464	I give up... I tried the cable of this thread, build it perfectly, and i get nothing from my Grundig Vivance LCD TV, i also tried the amigakit cable and nothing, i've tried 2 more schematics and still get nothing. Anyone has one of this tv and do you manage to get the amiga to work via Scart RGB Cable?

07 June 2010, 20:29	#106
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Some TV sets does not have true RGB inside, just composite.

07 June 2010, 21:13	#107
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,337	I'd bet money rkauer is right at the SCART socket you're trying to use does not support RGB.

24 October 2010, 09:12	#109
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,337	No and no. The grounds won't help with pixel timing and the "optional composite video connector" is to connect to the AMIGA side not the TV side!! Use your TV's controls to try to re-centre the picture.

27 October 2010, 00:42	#111
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,337	Nope. Have you tried anything else with RGB SCART on the same TV? Are they centred? A friend has a 42" Panasonic Plasma and A1200 RGB works fine, centred fine. Yes I know there are many different models and they all use different electronics but....

27 October 2010, 13:15	#112
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	I have the same problem with picture offcenter with Panasonic plasma TV. unfortunately the problem is that Amiga composite sync signal is "pure". usually csync signal in devices such as playstation and others, need some kind of decoding. and TV takes that delay into account. Amiga (and Amstrad for eg) don't need this 'decoding' so there is no delay. there are hardware devices to introduce this delay, they are sold on internet. iirc they are called "scart shifters" or similar: http://ntsc-uk.domino.org/showthread.php?t=100786

27 October 2010, 14:43	#113
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	@gafstu Can you get a picture of the offset picture? A standard workbench screen with the border on, would be great as it will help me to estimate how many microseconds I need to shift the video by. I have an idea for a simple circuit that will add a delay to the video sync that might fix it. @Orange Does the Playstation 2 exhibit the same issue? I have a Playstation 2 packed away so I could use this to measure any signal offsets. Video encoders add around 10us of delay, the hope is that by adding this, it is possible to offset the video accordingly. The descriptions here and on the ntsc-uk.domino.org site appear to back up the theory. Have seen similar issues on some high end equipment where we have needed to shift the video sync relative to the video data. Providing the jet lag does not hit me again, I plan to play in the workshop later. Ian

27 October 2010, 15:15	#114
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	@Stedy no, Playstation 2 picture is OK, as well as Wii.

27 October 2010, 20:51	#115
gafstu Posts: n/a	@Stedy I will get the screenshot at the weekend. If new circuitry is involved would it be easier to use an indivision ECS to give a VGA output? Presumably this wouldnt have the offset problem, and even if it did the PC input is adjustable on the panasonic plasma. Would VGA actually give better picture quality than scart anyway?

28 October 2010, 00:15	#116
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	@Gafstu The indivision ECS should be be a good solution albeit expensive. Both the VGA output of the indivision ECS and the Amiga RGB output, via SCART are analogue waveforms. With good quality cabling you should see no difference. I'm sure other users can testify to the quality of the indivision VGA output.Would like to keep this thread on topic relating to use a SCART socket/RGB input if possible. Ian

31 October 2010, 20:44	#117
gafstu Posts: n/a	@Stedy I bought a CD32 SCART cable off ebay as the CDTV has an RCA composite out like the CD32. This cable gives a perfect picture from the CDTV with no offset. I am not sure why this works when the DB23 output is offset, but i'm not complaining as the problem is solved! Thanks for your assistance. Ebay Item number: 320528976081

31 October 2010, 22:11	#118
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	its simple. afaik, CD32 has no RGB output. so that cable is cheap composite cable. the thing is, SCART has a lot of pins. so it can 'carry' RGB, CVBS, S-Video, audio... picture is centered but its lower quality than RGB.

31 October 2010, 23:14	#119
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	@Gafstu Did you try the SCART cable but using the composite video output of the Amiga to SCART pin 20? This uses the exact same video signal as your new video cable, going to the same input pin. @thread What I will do over the coming weeks, is collate the information I have on various Amiga video options into a guide, in a similar manner to my Amiga power supply guide. This will cover the various cable types and their relative merits, any adaptor boxes and what they achieve and some information on the PAL/NTSC modes of operation. I may ask for some contributions on hardware I do not own to add it to the guide. Will release a draft version on my website for you guys later this year. Ian

01 November 2010, 00:42	#120
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	perhaps that would be solution; use composite out connector instead of pin 10 (composite sync)? because tv will then have to "strip the C-Sync signal from the Composite Video signal." too bad it would make cable not so elegant. i know that these panasonic TVs have a "service menu", but dunno if it has options to center picture.

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