PAL RGB consoles on 1084S-D2

stefcep2 · 08 October 2022, 00:02

I'm trying to connect my PAL Gamecube and SNES to my 1084s-D2 via the analogue D-sub RGB connector.

After A LOT of trial and error I built a cable that has the Nintendo 12 pin male connector at one end and a d-sub male connector at the other end by simply wiring RGB, sync on composite and ground.

The Gamecube works very well.

The SNES has a rolling picture. I tried a sync stripper with a LM 1881 and it didn't work. I may need a sync on LUMA cable for the SNES.

Incidentally both work very well on a GBS 8220 using the cable and outputting to a VGA CRT. But the 1084 has the all important scanlines.

What I'm concerned about is the voltage output from the RGB lines. My A1200 outputs around 0.5V R and B with 1.2V on the G The gamecube around 1.2 V. The monitor specs say 0.7V p-p. I see SCART schematics with capacitors and resistors so I'm thinking this is to reduce the voltage output.

Daedalus · 08 October 2022, 00:36

I think the issue might be with the composite level. From memory, some of the Nintendo machines needed resistors in the composite lines to get their voltages in line with the spec, otherwise you got a totally washed out signal and sometimes a lack of sync.

stefcep2 · 08 October 2022, 02:12

The gamecube with the home-made RGB cable looks spectacular and I have no resistors or capacitors in the cable. The concern is the Red Green and Blue output voltage is above the input spec of the monitor ( but then so is the Green voltage coming out of the A1200). Could there a risk of damaging the monitor given the picture looks perfect?

Daedalus · 08 October 2022, 21:32

It probably won't, but if it's too high, everything will look washed out as it does in my composite example so you'll know straight away. Colours that look correct won't be out of spec, as anything at the top of the spec or higher will be 100% saturated. For me, the Gamecube looks spot on with no resistors, but the SNES and N64 needed a resistor to correctly set the output level. Since the sync is taken from the composite signal, it stands to reason that if the output level of that is incorrect then you could get a rolling picture.

stefcep2 · 08 October 2022, 23:44

Do you know the value of the resistor for the SNES?

Daedalus · 09 October 2022, 00:28

I can't remember off the top of my head, I just know I was mildly annoyed at not being able to use the same cable with the different consoles because one lacked the resistor. But now I'm thinking that the issue might be the other way - the Amiga Csync on the monitor port is TTL, i.e. 5V, and so the monitor's set up to use that. If the SNES cable is using the composite video signal for the composite sync, it might be much lower than 5V, and might need to be buffered.

stefcep2 · 09 October 2022, 00:46

The Voltage output of the gamecube composite is 0.5V. On the SNES about 3 V so yeah outside specs.

stefcep2 · 09 October 2022, 04:28

Tried sync on luma cable on the SNES and same rolling picture. Checked voltage across luma line and its zero. interesting given that s-video cables wouldn't work on this PAL console when it is supposed to output s-video-appears this console doesn't output luma.

Gods · 09 October 2022, 08:47

I've to do this modification on my SNES RGB cable to work on my PAL TV. I removed the x3 capacitors on it. You must see if you have those 75 Ohms resistors on the monitor because the SNES RGB output buffers need thoses to work (terminal resistor)

stefcep2 · 09 October 2022, 15:17

Thanks for that tip.

I'm using the 9 pin d sub pin out to the monitor not SCART:

http://www.zimmers.net/cbmpics/cbm/m...4s/pinout.html

I soldered one end of a 75 ohm resistor to the composite wire and the other to the ground pin and I was able to get a better result: the colors are perfect, but still a slowly rolling vertically image that occasionally syncs then rolls again.

Gods · 09 October 2022, 21:05

I know, i also have a 1085S monitor with a Sub-D DB9 input.
Why you don't use a 100 Ohm variable resistor to ground and adjust it to the best result ?
(Also you must try using the 3x 75 Ohm resistors on RGB wires)

stefcep2 · 10 October 2022, 03:56

I tried the 75 ohm resistors on R G B lines and no improvement. Color is good, image is not distorted. Same vertical rolling.

Has to be a vertical sync issue. Voltage on sync line is 1.0-1.2 I'll try with a potentiometer on the sync line as you suggest. Thank you!

Gods · 10 October 2022, 18:30

Little board with LM1881M... Only two passive components, one 100pF capacitor to PIN#2 and one 470_Ohm resistor to pin#1. VCC +12V i think.

09 October 2022, 08:47	#9
Gods Retro Gamer Join Date: Jun 2009 Location: GAN - France Age: 54 Posts: 22	I've to do this modification on my SNES RGB cable to work on my PAL TV. I removed the x3 capacitors on it. You must see if you have those 75 Ohms resistors on the monitor because the SNES RGB output buffers need thoses to work (terminal resistor) Attached Thumbnails

10 October 2022, 18:30	#13
Gods Retro Gamer Join Date: Jun 2009 Location: GAN - France Age: 54 Posts: 22	Little board with LM1881M... Only two passive components, one 100pF capacitor to PIN#2 and one 470_Ohm resistor to pin#1. VCC +12V i think. Attached Thumbnails

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08 October 2022, 00:02	#1
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	PAL RGB consoles on 1084S-D2 I'm trying to connect my PAL Gamecube and SNES to my 1084s-D2 via the analogue D-sub RGB connector. After A LOT of trial and error I built a cable that has the Nintendo 12 pin male connector at one end and a d-sub male connector at the other end by simply wiring RGB, sync on composite and ground. The Gamecube works very well. The SNES has a rolling picture. I tried a sync stripper with a LM 1881 and it didn't work. I may need a sync on LUMA cable for the SNES. Incidentally both work very well on a GBS 8220 using the cable and outputting to a VGA CRT. But the 1084 has the all important scanlines. What I'm concerned about is the voltage output from the RGB lines. My A1200 outputs around 0.5V R and B with 1.2V on the G The gamecube around 1.2 V. The monitor specs say 0.7V p-p. I see SCART schematics with capacitors and resistors so I'm thinking this is to reduce the voltage output. Last edited by stefcep2; 08 October 2022 at 00:17.

08 October 2022, 00:36	#2
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,364	I think the issue might be with the composite level. From memory, some of the Nintendo machines needed resistors in the composite lines to get their voltages in line with the spec, otherwise you got a totally washed out signal and sometimes a lack of sync.

08 October 2022, 02:12	#3
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	The gamecube with the home-made RGB cable looks spectacular and I have no resistors or capacitors in the cable. The concern is the Red Green and Blue output voltage is above the input spec of the monitor ( but then so is the Green voltage coming out of the A1200). Could there a risk of damaging the monitor given the picture looks perfect?

08 October 2022, 21:32	#4
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,364	It probably won't, but if it's too high, everything will look washed out as it does in my composite example so you'll know straight away. Colours that look correct won't be out of spec, as anything at the top of the spec or higher will be 100% saturated. For me, the Gamecube looks spot on with no resistors, but the SNES and N64 needed a resistor to correctly set the output level. Since the sync is taken from the composite signal, it stands to reason that if the output level of that is incorrect then you could get a rolling picture.

08 October 2022, 23:44	#5
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	Do you know the value of the resistor for the SNES?

09 October 2022, 00:28	#6
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,364	I can't remember off the top of my head, I just know I was mildly annoyed at not being able to use the same cable with the different consoles because one lacked the resistor. But now I'm thinking that the issue might be the other way - the Amiga Csync on the monitor port is TTL, i.e. 5V, and so the monitor's set up to use that. If the SNES cable is using the composite video signal for the composite sync, it might be much lower than 5V, and might need to be buffered.

09 October 2022, 00:46	#7
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	The Voltage output of the gamecube composite is 0.5V. On the SNES about 3 V so yeah outside specs.

09 October 2022, 04:28	#8
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	Tried sync on luma cable on the SNES and same rolling picture. Checked voltage across luma line and its zero. interesting given that s-video cables wouldn't work on this PAL console when it is supposed to output s-video-appears this console doesn't output luma.

09 October 2022, 15:17	#10
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	Thanks for that tip. I'm using the 9 pin d sub pin out to the monitor not SCART: http://www.zimmers.net/cbmpics/cbm/m...4s/pinout.html I soldered one end of a 75 ohm resistor to the composite wire and the other to the ground pin and I was able to get a better result: the colors are perfect, but still a slowly rolling vertically image that occasionally syncs then rolls again.

09 October 2022, 21:05	#11
Gods Retro Gamer Join Date: Jun 2009 Location: GAN - France Age: 54 Posts: 22	I know, i also have a 1085S monitor with a Sub-D DB9 input. Why you don't use a 100 Ohm variable resistor to ground and adjust it to the best result ? (Also you must try using the 3x 75 Ohm resistors on RGB wires)

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10 October 2022, 03:56	#12
stefcep2 Registered User Join Date: Dec 2009 Location: Melbourne/Australia Posts: 226	I tried the 75 ohm resistors on R G B lines and no improvement. Color is good, image is not distorted. Same vertical rolling. Has to be a vertical sync issue. Voltage on sync line is 1.0-1.2 I'll try with a potentiometer on the sync line as you suggest. Thank you!