RGB Scart Issues...

PowerPie5000 · 23 June 2011, 21:40

I bought a scart cable from Airey36 on ebay (i've dealt with him on a few occasions) but it doesn't seem to work! All i get is a blank (black) screen when i try using it with my A500+ and A1200.

Anyway, the cable itself looks as though it's been left outside as the scart end has a few patches of rust and i've also noticed a lack of resistors in this cable (there are none at all)... Are they needed? I've tried the cable with a few TV's.

Anyone have any idea's? I contacted the seller earlier today and i'm still waiting for a reply.

alexh · 23 June 2011, 22:53

Check the SCART pinout and pay attention to RGB MODE (SCART pin 16) and SWITCH (SCART pin 8)

http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

thomas · 23 June 2011, 22:54

Quote:

All i get is a blank (black) screen when i try using it with my A500+ and A1200.

Make sure that your TV supports RGB over Scart. If your TV has multiple Scart plugs, it might be that only one of them supports RGB. You might also need to manually switch the TV into RGB mode if the cable is missing the necessary resistors for auto switching.

PowerPie5000 · 23 June 2011, 23:49

Quote:

Originally Posted by alexh

Check the SCART pinout and pay attention to RGB MODE (SCART pin 16) and SWITCH (SCART pin 8)

http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

Both pin 16 and pin 8 are connected on the scart end but don't have any resistors attached... Could this be the problem? It was even listed as tested and working

Quote:

Originally Posted by thomas

Make sure that your TV supports RGB over Scart. If your TV has multiple Scart plugs, it might be that only one of them supports RGB. You might also need to manually switch the TV into RGB mode if the cable is missing the necessary resistors for auto switching.

I've tried it with 3 different CRT TV's that i know support RGB... I'm not even going to risk testing it with my LCD screens. It seems to auto switch but the screen stays black.

fitzsteve · 23 June 2011, 23:53

I've had a couple of Scarts that didn't work on any of my TV's but did work on my old 1084, it can be luck of the draw unless you buy one of Amigakits Scarts that are build to Steady's spec.

I'm sure Airey will swap or refund it for you.

Steve.

alexh · 24 June 2011, 13:51

Quote:

Originally Posted by PowerPie5000

Both pin 16 and pin 8 are connected on the scart end but don't have any resistors attached... Could this be the problem?

On an LCD maybe, on a CRT doubtful. As long as pin 16 has +5v it should switch to RGB mode.

If you have a multi-meter (battery + bulb) buzz out the connections WRT that diagram I linked to? Make sure it is wired correctly?

PowerPie5000 · 24 June 2011, 22:17

Quote:

Originally Posted by alexh

On an LCD maybe, on a CRT doubtful. As long as pin 16 has +5v it should switch to RGB mode.

If you have a multi-meter (battery + bulb) buzz out the connections WRT that diagram I linked to? Make sure it is wired correctly?

Cheers for the suggestion but i've posted the cable back to the seller and he's posted out a replacement (fingers crossed for the next one

).

PowerPie5000 · 27 June 2011, 16:10

Got the replacement cable and it works fine with only one of my CRT TV's (which happens to be the oldest one too... A Goodmans model).

This cable has no resistors on the scart end but has a cluster of 3 resistors on pin 10 and also a cluster of 3 resistors on pin 23 with only a single resistor on pin 22 (all attached to the 23-pin RGB connector).

I'm not too sure on the values:

2 x resistors have red, red, red, gold bands (both connected to pin 10)
2 x resistors have red, red, brown, gold bands (both connected to pin 23)
2 x resistors have yellow, purple, brown, gold bands (one connected to pin 10 and the other connected to pin 22).
1 x resistor has brown, black, red, gold bands (connected to pin 22)

I tried to work out the values but didn't know if the last band (gold) was the tolerance or multiplier on each resistor (they all have 4 bands)... My calculations seemed a bit too high so are probably wrong

Any help, explanations or advice is always appreciated, Cheers

Hewitson · 27 June 2011, 16:31

2 x resistors have red, red, red, gold bands (both connected to pin 10) 2k2
2 x resistors have red, red, brown, gold bands (both connected to pin 23) 220R
2 x resistors have yellow, purple, brown, gold bands (one connected to pin 10 and the other connected to pin 22). 470R
1 x resistor has brown, black, red, gold bands (connected to pin 22) 1k

orange · 27 June 2011, 22:18

I would measure the voltage on pin 16 compared to pin 18.

PowerPie5000 · 28 June 2011, 14:36

Quote:

Originally Posted by Hewitson

2 x resistors have red, red, red, gold bands (both connected to pin 10) 2k2
2 x resistors have red, red, brown, gold bands (both connected to pin 23) 220R
2 x resistors have yellow, purple, brown, gold bands (one connected to pin 10 and the other connected to pin 22). 470R
1 x resistor has brown, black, red, gold bands (connected to pin 22) 1k

That means there's almost 5k (4870R) on pin 10 (pin 20 on scart end), 1k on pin 22 (pin 8 on scart end) and 910R on pin 23 (pin 16 on scart end)... Does that seem a bit high?

Quote:

Originally Posted by orange

I would measure the voltage on pin 16 compared to pin 18.

Unfortunately i don't have a multi meter handy... What effect do pins 16 and 18 have? Are you talking about pins on the scart or 23-pin RGB connector?

alexh · 28 June 2011, 14:48

SCART pin 16 is RGB, without 1-3v on this pin you will get a BLANK screen.

SCART pin 18 is RGB ground. The value against which pin 16 is measured by.

SCART pin 8 is AV-Select and Aspect Ratio. No voltage on this pin and the TV will not switch to AV channel when Amiga is turned on. Less than 9V and the TV will stay in Widescreen. Should be 9.5v+

SCART pin 20 is Composite Video (Sync) and the Amiga outputs TTL (2V pk-pk) and TV expects 1V. Wrong voltage (i.e. no resistor) on this pin normally doesn't affect CRT, just TFT.

Quote:

Originally Posted by PowerPie5000

That means there's almost 5k (4870R) between Amiga pin 10 and SCART pin 20

Should be 330 Ohm. I'm surprised this cable works at all!

Quote:

Originally Posted by PowerPie5000

1k between Amiga pin 22 and SCART pin 8

That is correct.

Quote:

Originally Posted by PowerPie5000

and 910R between Amiga pin 23 and SCART pin 16

Should be 75 ohm. I think that should be fine it will still lie between the 1v and 3v range

PowerPie5000 · 29 June 2011, 08:39

I've just realised that that the total resistance on pin 22 and 23 shouldn't be as high as i first thought... Whoever built the cable has joined 3 resistors together in parallel on both pins 22 and 23... I understand this means the resistance will be lower as electricity will take the path with the least resistance. Is this true (it's been years since my college days

)?

I may just remove the extra resistors on those pins.

moijk · 29 June 2011, 09:36

Quote:

Originally Posted by PowerPie5000

I've just realised that that the total resistance on pin 22 and 23 shouldn't be as high as i first thought... Whoever built the cable has joined 3 resistors together in parallel on both pins 22 and 23... I understand this means the resistance will be lower as electricity will take the path with the least resistance. Is this true (it's been years since my college days

)?

I may just remove the extra resistors on those pins.

Surfing Amiga forums is always a fun thing to do because the users here see problems in a different way. Any other user would just toss out the cable and get a new one. Here it's a challenge!

FOL · 29 June 2011, 12:07

Quote:

Originally Posted by PowerPie5000

I've just realised that that the total resistance on pin 22 and 23 shouldn't be as high as i first thought... Whoever built the cable has joined 3 resistors together in parallel on both pins 22 and 23... I understand this means the resistance will be lower as electricity will take the path with the least resistance. Is this true (it's been years since my college days

)?

I may just remove the extra resistors on those pins.

Aye, in parallel they halve the resistance.
In series they double the resistance.

But if you have removed the extra, that would mean the values are much higher?

PowerPie5000 · 29 June 2011, 16:02

Quote:

Originally Posted by FOL

Aye, in parallel they halve the resistance.
In series they double the resistance.

But if you have removed the extra, that would mean the values are much higher?

I meant to say pins 10 and 23 have 3 resistors, not pin 22 (which uses a single 1k resistor)... I could remove the 2K2 resistors from pin 10 which will leave a single 470 ohm resistor although i've not seen any pinout digrams that use a resistor on pin 10 (pin 20 on the scart end). Or maybe i should just buy another cable.

PowerPie5000 · 29 June 2011, 16:28

Ok i'm now left with a 220 ohm resistor on pin 23 (pin 16 scart end) and a 470 ohm resistor on pin 10 (pin 20 on scart end). I left the 1k resistor on pin 22 (pin 8 on the scart end)... Time to try it with my other CRT screens.

EDIT: Well that made no difference at all... It still only works on my old Goodmans CRT screen and just displays a blank screen on the others.

FOL · 29 June 2011, 22:35

Quote:

Originally Posted by PowerPie5000

Ok i'm now left with a 220 ohm resistor on pin 23 (pin 16 scart end) and a 470 ohm resistor on pin 10 (pin 20 on scart end). I left the 1k resistor on pin 22 (pin 8 on the scart end)... Time to try it with my other CRT screens.

EDIT: Well that made no difference at all... It still only works on my old Goodmans CRT screen and just displays a blank screen on the others.

Are you sure, those tv's accept RGB on the scart?

Other than that use the values alex stated.

PowerPie5000 · 30 June 2011, 00:09

Quote:

Originally Posted by FOL

Are you sure, those tv's accept RGB on the scart?

Other than that use the values alex stated.

Yes, all my TV's fully support RGB via scart (usually the first scart socket if there's more than one). I'll change over the resistors and see what happens. Everything else seems to be in order regarding ground pins and shielding etc... But there are a couple of looped wires on the 23-pin RGB connecter end, is that normal?

Are the Amigakit RGB scart cables built to Ian Stedmans spec?

http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

Those look to be the same values as alex mentioned.

prowler · 30 June 2011, 00:22

Quote:

Originally Posted by PowerPie5000

Are the Amigakit RGB scart cables built to Ian Stedmans spec?

http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

Those look to be the same values as alex mentioned.

Yes, they are (built to Ian Stedman's spec).

23 June 2011, 21:40	#1
PowerPie5000 Miggy Ate My Hamster! Join Date: Nov 2008 Location: Lancashire, UK Posts: 1,566	RGB Scart Issues... I bought a scart cable from Airey36 on ebay (i've dealt with him on a few occasions) but it doesn't seem to work! All i get is a blank (black) screen when i try using it with my A500+ and A1200. Anyway, the cable itself looks as though it's been left outside as the scart end has a few patches of rust and i've also noticed a lack of resistors in this cable (there are none at all)... Are they needed? I've tried the cable with a few TV's. Anyone have any idea's? I contacted the seller earlier today and i'm still waiting for a reply.

29 June 2011, 16:28	#17
PowerPie5000 Miggy Ate My Hamster! Join Date: Nov 2008 Location: Lancashire, UK Posts: 1,566	Ok i'm now left with a 220 ohm resistor on pin 23 (pin 16 scart end) and a 470 ohm resistor on pin 10 (pin 20 on scart end). I left the 1k resistor on pin 22 (pin 8 on the scart end)... Time to try it with my other CRT screens. EDIT: Well that made no difference at all... It still only works on my old Goodmans CRT screen and just displays a blank screen on the others. Last edited by PowerPie5000; 29 June 2011 at 16:41.

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23 June 2011, 22:53	#2
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,448	Check the SCART pinout and pay attention to RGB MODE (SCART pin 16) and SWITCH (SCART pin 8) http://www.ianstedman.co.uk/Amiga/am...iga_scart.html

23 June 2011, 23:53	#5
fitzsteve Professional slacker! Join Date: Jul 2009 Location: Kent, UK Age: 44 Posts: 6,685	I've had a couple of Scarts that didn't work on any of my TV's but did work on my old 1084, it can be luck of the draw unless you buy one of Amigakits Scarts that are build to Steady's spec. I'm sure Airey will swap or refund it for you. Steve.

27 June 2011, 16:10	#8
PowerPie5000 Miggy Ate My Hamster! Join Date: Nov 2008 Location: Lancashire, UK Posts: 1,566	Got the replacement cable and it works fine with only one of my CRT TV's (which happens to be the oldest one too... A Goodmans model). This cable has no resistors on the scart end but has a cluster of 3 resistors on pin 10 and also a cluster of 3 resistors on pin 23 with only a single resistor on pin 22 (all attached to the 23-pin RGB connector). I'm not too sure on the values: 2 x resistors have red, red, red, gold bands (both connected to pin 10) 2 x resistors have red, red, brown, gold bands (both connected to pin 23) 2 x resistors have yellow, purple, brown, gold bands (one connected to pin 10 and the other connected to pin 22). 1 x resistor has brown, black, red, gold bands (connected to pin 22) I tried to work out the values but didn't know if the last band (gold) was the tolerance or multiplier on each resistor (they all have 4 bands)... My calculations seemed a bit too high so are probably wrong Any help, explanations or advice is always appreciated, Cheers

27 June 2011, 16:31	#9
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	2 x resistors have red, red, red, gold bands (both connected to pin 10) 2k2 2 x resistors have red, red, brown, gold bands (both connected to pin 23) 220R 2 x resistors have yellow, purple, brown, gold bands (one connected to pin 10 and the other connected to pin 22). 470R 1 x resistor has brown, black, red, gold bands (connected to pin 22) 1k

27 June 2011, 22:18	#10
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	I would measure the voltage on pin 16 compared to pin 18.

29 June 2011, 08:39	#13
PowerPie5000 Miggy Ate My Hamster! Join Date: Nov 2008 Location: Lancashire, UK Posts: 1,566	I've just realised that that the total resistance on pin 22 and 23 shouldn't be as high as i first thought... Whoever built the cable has joined 3 resistors together in parallel on both pins 22 and 23... I understand this means the resistance will be lower as electricity will take the path with the least resistance. Is this true (it's been years since my college days )? I may just remove the extra resistors on those pins.

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