Stedy's RGB to SCART cable - Page 3

Supamax · 10 October 2009, 01:51

Quote:

Originally Posted by Stedy

Hi,
@supamax
On your first cable you have no +12V connection to pin 8 of the SCART lead, this means the TV is not set to 4:3 RGB
mode.

Ian

So is it normal that it perfectly works with my Philips CM 8833 and not with "mere" TVs?

Stedy · 12 October 2009, 21:19

Quote:

Originally Posted by Supamax

So is it normal that it perfectly works with my Philips CM 8833 and not with "mere" TVs?

Yes.

The CM8833 takes HSYNC, VSYNC and RGB video. A SCART TV needs some control signals select the correct mode of operation so the lack of AV mode signal will not affect the operation of the CM8833.

8bitbubsy · 13 October 2009, 22:33

Any difference on this and the one sold on Amigakit? I mean, in the hardware strategy/picture quality...

Stedy · 03 November 2009, 01:26

Hi,

Just a quick update, I have the components in stock now to allow me to experiment with the cheaper CPLD sync circuit and the more expensive video decoder/encoder and scandoubler parts. PCB design should start in the next month.

Supamax · 26 November 2009, 04:39

Quote:

Originally Posted by Stedy

Hi,
@supamax
On your first cable you have no +12V connection to pin 8 of the SCART lead, this means the TV is not set to 4:3 RGB
mode.

Ian

You are right, but if I manually switch to AV mode I can see the Amiga display.

Muzer · 29 November 2009, 14:25

On a homebrew-looking SCART cable I got with my CDTV, which works fine on the one TV I've tested it on, the following aren't connected (on the SCART end):

5
9
13
18

8 is connected to the same wire as 16, but with different resistors between - haven't checked the effects on a widescreen TV, but SCART mode switching works fine...

So basically, the only ground is composite ground... still seems to work though, but I dunno if it is displaying true RGB or not... I think it is as the picture seems sharper.

alexh · 29 November 2009, 14:49

Quote:

Originally Posted by Muzer

the following aren't connected (on the SCART end):
5
9
13
18

They are all grounds. Less important for CRT TV's but becoming increasingly more important on LCD TV's.

Quote:

Originally Posted by Muzer

8 is connected to the same wire as 16, but with different resistors between

Fine as long as the resistors are the right value.

Quote:

Originally Posted by Muzer

I dunno if it is displaying true RGB or not... I think it is as the picture seems sharper.

23-pin Amiga socket only has RGB. If it was not "displaying true RGB" you'd have a black screen.

Muzer · 29 November 2009, 14:52

Oh right - I assumed it had composite somewhere. So what is the composite video connected to then, because it's definitely connected (and has a resistor)?

It is an LCD TV it works fine on, btw, though the picture is slightly noisy still (the colours still bleed a little, esp. black) - would connecting up the other grounds fix it?

alexh · 29 November 2009, 16:02

Quote:

Originally Posted by Muzer

So what is the composite video connected to then?

Composite sync OUT (on the Amiga) is connected to composite video IN (on the SCART) conveying just the horizontal and vertical position information, no picture.

Quote:

Originally Posted by Muzer

would connecting up the other grounds fix it?

Unknown, couldn't hurt if you are an accomplished solderer and can put in all the small bridges at the SCART end of the cable.

Stedy · 30 November 2009, 01:12

Hello,

I have finally got around to adding the full RGB/SCART guide to my website.
Take a look here:
http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

Have added some oscilloscope traces and test results from the other TVs that I tested, corrected a few typos and re-arranged the document slightly to make it flow better.

Ian

Jonathan Drain · 30 November 2009, 18:43

Where do you buy DB23 connectors in the UK?

PowerPie5000 · 30 November 2009, 19:12

Quote:

Originally Posted by Jonathan Drain

Where do you buy DB23 connectors in the UK?

Try a Maplin Electronics store... they seem to be everywhere these days but i think their prices can sometimes be a bit high.

alexh · 30 November 2009, 19:39

No-where in the UK that I've found (including Maplin) sell new DB-23 connectors (and shrouds).

The only mass produced item which ever used them was the Amiga (just like 13-pin DIN on Atari ST). There are the odd place online selling NOS in USA or China for about $4 inc shroud but usually you've got to buy a large number.

You can cut down a DB25-pin if you have to.

lopos2000 · 30 November 2009, 20:12

Quote:

Originally Posted by PowerPie5000

Try a Maplin Electronics store... they seem to be everywhere these days but i think their prices can sometimes be a bit high.

No. They don't have any DB23 connector only the housing.

alexh · 30 November 2009, 20:26

Quote:

Originally Posted by lopos2000

They don't have any DB23 connector only the housing.

Is that cos it's the same as DB25?

alexh · 02 December 2009, 13:31

They sell 23-pin D connectors here

http://www.retro-data.com/

€11.97 for two

Photon · 03 December 2009, 08:19

Ah, that spanish site. Great, but sounds like you could save a bunch by doing the 25->23 mod... you can make it pretty-ish with a Dremel, and it's covered by the Amiga D-sub, so...

bebek · 23 December 2009, 00:13

I have made 2 days ago RGB cable, as I did not have much time (spent all on fighting with apollo 060) I did not use any resistors: RGB to RGB, CSYNCH to CSYNCH, 5V to RGB switch line and it works like a charm ... . Connected to high end, top quality, HD not ready TV, made special for Sainsbury and called RED. So, I switched it to PAL Hires Laced and the image is stable

, no blinking - it looks like my Scandy is going to be sold as it is not needed anymore

.

Photon · 23 December 2009, 00:39

LCD or CRT?

bebek · 23 December 2009, 00:51

It is LCD 15.4".

30 November 2009, 19:39	#53
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,337	No-where in the UK that I've found (including Maplin) sell new DB-23 connectors (and shrouds). The only mass produced item which ever used them was the Amiga (just like 13-pin DIN on Atari ST). There are the odd place online selling NOS in USA or China for about $4 inc shroud but usually you've got to buy a large number. You can cut down a DB25-pin if you have to. Last edited by alexh; 30 November 2009 at 19:47.

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13 October 2009, 22:33	#43
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,710	Any difference on this and the one sold on Amigakit? I mean, in the hardware strategy/picture quality...

03 November 2009, 01:26	#44
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	Hi, Just a quick update, I have the components in stock now to allow me to experiment with the cheaper CPLD sync circuit and the more expensive video decoder/encoder and scandoubler parts. PCB design should start in the next month.

29 November 2009, 14:25	#46
Muzer Registered User Join Date: Sep 2009 Location: UK Posts: 146	On a homebrew-looking SCART cable I got with my CDTV, which works fine on the one TV I've tested it on, the following aren't connected (on the SCART end): 5 9 13 18 8 is connected to the same wire as 16, but with different resistors between - haven't checked the effects on a widescreen TV, but SCART mode switching works fine... So basically, the only ground is composite ground... still seems to work though, but I dunno if it is displaying true RGB or not... I think it is as the picture seems sharper.

29 November 2009, 14:52	#48
Muzer Registered User Join Date: Sep 2009 Location: UK Posts: 146	Oh right - I assumed it had composite somewhere. So what is the composite video connected to then, because it's definitely connected (and has a resistor)? It is an LCD TV it works fine on, btw, though the picture is slightly noisy still (the colours still bleed a little, esp. black) - would connecting up the other grounds fix it?

30 November 2009, 01:12	#50
Stedy Registered User Join Date: Jan 2008 Location: United Kingdom Age: 46 Posts: 733	Hello, I have finally got around to adding the full RGB/SCART guide to my website. Take a look here: http://www.ianstedman.co.uk/Amiga/am...iga_scart.html Have added some oscilloscope traces and test results from the other TVs that I tested, corrected a few typos and re-arranged the document slightly to make it flow better. Ian

30 November 2009, 18:43	#51
Jonathan Drain Registered User Join Date: Sep 2009 Location: Sector K240 Posts: 338	Where do you buy DB23 connectors in the UK?

02 December 2009, 13:31	#56
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,337	They sell 23-pin D connectors here http://www.retro-data.com/ €11.97 for two

03 December 2009, 08:19	#57
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	Ah, that spanish site. Great, but sounds like you could save a bunch by doing the 25->23 mod... you can make it pretty-ish with a Dremel, and it's covered by the Amiga D-sub, so...

23 December 2009, 00:13	#58
bebek Registered User Join Date: Dec 2009 Location: Poole UK Posts: 349	I have made 2 days ago RGB cable, as I did not have much time (spent all on fighting with apollo 060) I did not use any resistors: RGB to RGB, CSYNCH to CSYNCH, 5V to RGB switch line and it works like a charm ... . Connected to high end, top quality, HD not ready TV, made special for Sainsbury and called RED. So, I switched it to PAL Hires Laced and the image is stable , no blinking - it looks like my Scandy is going to be sold as it is not needed anymore .

23 December 2009, 00:39	#59
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	LCD or CRT?

23 December 2009, 00:51	#60
bebek Registered User Join Date: Dec 2009 Location: Poole UK Posts: 349	It is LCD 15.4".

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